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Patterns of Gondwana plant colonisation anddiversification
Abstract
Charting the broad patterns of vascular plant evolution for Gondwana against the major global environmental shifts and events is attempted here for the first time. This is based on the analysis of the major vascular plant-bearing formations of the southern continents (plus India) correlated against the standard geological time-scale. Australia, followed closely by South America, are shown to yield by far the most complete sequences of productive strata. Ten seminal turnover pulses in the unfolding evolutionary picture are identified and seen to be linked to continental drift, climate change and mass global extinctions. The rise of vascular plants along the tropical belt, for instance, followed closely after the end-Ordovician warming and extinction. Equally remarkable is that the Late Devonian extinction may have caused both the terrestrialisation of the vertebrates and the origin of the true gymnosperms. The end-Permian extinction, closure of lapetus, together with warming, appears to have set in motion an unparalleled, explosive, gymnosperm radiation; whilst the Late Triassic extinction dramatically curtailed it. It is suggested that the latitudinal diversity gradient clearly recognised today, where species richness increases towards the tropics, may have been partly reversed during phases of Hot House climate. Evidence hints at this being particularly so at the heyday of the gymnosperms in the Late Triassic super-Hot House world. As for the origin of terrestrial, vascular, plant life, the angiosperms seem closely linked to a phase of marked shift from Ice House to Hot House. Insect and tetrapod evolutionary patterns are discussed in the context of the plants providing the base of the ever-changing ecosystems. Intimate co-evolution is often evident. This isn't always the case, for example the non-linkage between the dominant, giant, long-necked, herbivorous sauropod dinosaurs and the dramatic radiation of the flowering plants in the Mid-Cretaceous.
... Following the Oxfordian warming period (e.g. Weissert & Erba, 2004;Jenkyns et al., 2012), there was an increase in global temperatures in the Kimmeridgian (Anderson et al., 1999;Scotese, Baucot & McKerrow, 1999;Bergman, Lenton & Watson, 2004;Price & Passey, 2013;Meyers, 2014). Increasing atmospheric temperatures through the Late Jurassic are consistent with results from the GEOCARBSULF model, although at a lower resolution (Berner, 2006(Berner, , 2009. ...
... Articulate brachiopods, gastropods, bivalves and ammonites all declined in diversity at the J/K boundary, with the latter two groups showing evidence for regional selectivity (Alroy, 2010a;Rogov et al., 2010), alongside a higher extinction intensity in northern hemisphere taxa (Alroy, 2010b). Additionally, these groups exhibited latitudinal constraints on diversity, possibly driven by large-scale changes in global climate regimes at the J/K boundary (Anderson et al., 1999;Scotese et al., 1999;Bergman et al., 2004;Meyers, 2014). Such constraints might be responsible for global declines in diversity (Peters & Foote, 2001;Smith & McGowan, 2007;Lu et al., 2009;Alroy, 2010b;Rogov et al., 2010;Valentine & Jablonski, 2010;Smith et al., 2012), and the reorganisation of marine ecosystems through the J/K boundary. ...
... The decline of reefs over the J/K boundary was probably also tied to changes in global temperatures (Anderson et al., 1999;Scotese et al., 1999;Bergman et al., 2004;Martin-Garin et al., 2010). Additionally, it is likely that factors relating to sea-level changes, including declining salinity and shifts in nutrient flux systems, constrained organisms to increasingly rare shallower shelf systems over the J/K boundary and until the middle Cretaceous (Hay et al., 2006). ...
The Late Jurassic to Early Cretaceous interval represents a time of environmental upheaval and cataclysmic events, combined with disruptions to terrestrial and marine ecosystems. Historically, the Jurassic/Cretaceous (J/K) boundary was classified as one of eight mass extinctions. However, more recent research has largely overturned this view, revealing a much more complex pattern of biotic and abiotic dynamics than has previously been appreciated. Here, we present a synthesis of our current knowledge of Late Jurassic–Early Cretaceous events, focusing particularly on events closest to the J/K boundary. We find evidence for a combination of short-term catastrophic events, large-scale tectonic processes and environmental perturbations, and major clade interactions that led to a seemingly dramatic faunal and ecological turnover in both the marine and terrestrial realms. This is coupled with a great reduction in global biodiversity which might in part be explained by poor sampling. Very few groups appear to have been entirely resilient to this J/K boundary ‘event’, which hints at a ‘cascade model’ of ecosystem changes driving faunal dynamics. Within terrestrial ecosystems, larger, more-specialised organisms, such as saurischian dinosaurs, appear to have suffered the most. Medium-sized tetanuran theropods declined, and were replaced by larger-bodied groups, and basal eusauropods were replaced by neosauropod faunas. The ascent of paravian theropods is emphasised by escalated competition with contemporary pterosaur groups, culminating in the explosive radiation of birds, although the timing of this is obfuscated by biases in sampling. Smaller, more ecologically diverse terrestrial non-archosaurs, such as lissamphibians and mammaliaforms, were comparatively resilient to extinctions, instead documenting the origination of many extant groups around the J/K boundary. In the marine realm, extinctions were focused on low-latitude, shallow marine shelf-dwelling faunas, corresponding to a significant eustatic sea-level fall in the latest Jurassic. More mobile and ecologically plastic marine groups, such as ichthyosaurs, survived the boundary relatively unscathed. High rates of extinction and turnover in other macropredaceous marine groups, including plesiosaurs, are accompanied by the origin of most major lineages of extant sharks. Groups which occupied both marine and terrestrial ecosystems, including crocodylomorphs, document a selective extinction in shallow marine forms, whereas turtles appear to have diversified. These patterns suggest that different extinction selectivity and ecological processes were operating between marine and terrestrial ecosystems, which were ultimately important in determining the fates of many key groups, as well as the origins of many major extant lineages. We identify a series of potential abiotic candidates for driving these patterns, including multiple bolide impacts, several episodes of flood basalt eruptions, dramatic climate change, and major disruptions to oceanic systems. The J/K transition therefore, although not a mass extinction, represents an important transitional period in the co-evolutionary history of life on Earth.
... The Triassic Period spans an interval of 51 million years approximately (from 252 to 201 Mya) and is characterized by the recovery, origination, and diversification of the biota after the end-Permian mass extinction (Anderson et al., 1999;Willis and McElwain, 2014;Vajda and Bercovici, 2014). The post-extinction recovery and evolution of terrestrial ecosystems was controlled and affected by several variables. ...
... The Dicroidium flora is characterized by the dominance of Umkomasiaceae, an endemic family from Gondwana. Also, this flora includes cosmopolitan taxa referred to Equisetales (Equisetites, Neocalamites), Lycopsida (Pleuromeia), Osmundales (Cladophlebis), Peltaspermales (Lepidopteris, Scytophyllum), Bennettitales (Pterophyllum, Anomozamites, Ctenis, Pseudoctenis), Ginkgoales (Ginkgoites, Baiera, Sphenobaiera) and Voltziales (Heidiphyllum) (Retallack, 1977;Anderson and Anderson, 1983;Anderson et al., 1999;Spalletti et al., 1999;Artabe et al., 2001aArtabe et al., , 2001bZamuner et al., 2001;Stipanicic and Archangelsky, 2002;Kustatscher et al., 2018). The representation and distribution of these groups vary geographically and in the number of taxa, increasing or decreasing over time in response to climatic variations and events such as the Carnian Pluvial Event (Kustatscher et al., 2018). ...
Earth's land plants have been shaped by tectonic, climatic and atmospheric evolution for at least 400 million years. The rift basins of Argentina record a continuous record of Triassic paleofloras through a wide paleolatitudinal range offer an opportunity to study the effect of paleoclimate on paleofloral changes through the Triassic period. We review previous work on southwestern Gondwana paleofloras of the Argentinean Triassic System and study the relationship between the palaeobotanical record and the inferred paleoclimatic conditions. The bibliographic review data were used to generate a presence/absence matrix. A cluster analysis, and a principal components analysis (PCA) were carried out to explore relationships among paleofloras. Also, variations in total number of genera per Triassic stage were plotted to elucidate biodiversity trends in the paleobotanical record. Finally, a canonical correspondence analysis (CCA) was performed in order to explore the relationship between the Triassic paleofloristic data and their interpreted paleoclimatic parameters, The influence of potential collection, taphonomic bias, and the uncertainties of the chronostrigraphic framework, on the integrity of the data are discussed. We conclude that the Early Triassic paleofloras developed under arid to semiarid with a marked concentration of seasonal precipitation during the summers; Middle Triassic under semi-arid to sub-humid with precipitation concentration during the summers; and Late Triassic paleofloras during early Carnian developed first under warm humid conditions without marked seasonality but by the Norian and Rhaetian conditions changed to semi-arid with winter rainfall.
... Fossils from these regions yield insights into the diversity and biology of the trees growing in these ecosystems with no modern analogue, that is warm polar forests with a strongly seasonal light regime (Creber 1990;Francis 1994;Taylor & Ryberg 2007;Gulbranson et al. 2014;Slater et al. 2015;Miller et al. 2016). In the Late Permian, the high-latitude forests of the Southern Hemisphere were largely dominated by trees belonging to an extinct order of seed plants, the Glossopteridales (Cúneo et al. 1993;Anderson et al. 1999;Taylor et al. 2009). Glossopterid trees produced very distinctive roots assigned to the genus Vertebraria Royle that are characterized by wood with conspicuous lacunae formed by a discontinuous cambium in the first seasons of growth (Neish et al. 1993;Decombeix et al. 2009). ...
... Mosses, lycopsids and ferns are each represented by a single species (Smoot & Taylor 1986;Galtier & Taylor 1994;Ryberg et al. 2012). Sphenophytes have not been identified, although they co-occur with Glossopteris in many plant assemblages from Antarctica and the rest of Gondwana (Cúneo et al. 1993;Anderson et al. 1999;Prevec et al. 2009;Slater et al. 2015). Evidence of non-glossopterid seed plants in the peat from Skaar Ridge is also scarce. ...
The biology of trees that grew in high‐latitude forests during warmer geological periods is of major interest in understanding past and future ecosystem dynamics. As we study the different plants that composed these forests, it becomes possible to make comparisons with ecosystem processes that occur today. Here we describe a silicified late Permian (Lopingian) glossopterid (seed fern) trunk from Skaar Ridge, central Transantarctic Mountains, Antarctica, with evidence of glossopterid rootlets growing into its wood. The specimen is interpreted as a nurse log similar to those seen in some extant forests. Together with evidence of glossopterid roots growing within the lacunae of older roots, this new specimen suggests the existence of facilitative interactions among the glossopterid trees that dominated the high‐latitude forests of Gondwana during the late Permian. More generally, the existence of self‐facilitation might have favoured the expansion of glossopterids within various environments, especially those at high palaeolatitudes, during the Permian icehouse to greenhouse transition.
... 59.60%) of various species of striate bisaccate pollens and cuticles of glossopterids (9 genera; 33 species; Fig. 9) viz., Striatopodocarpites, Faunipollenites, and Crescentipollenites, etc. (Figs. 5 and 8). The acme of glossopterids was consistently instituted across the Southern Hemisphere during the late Permian representing "a heyday of Glossopterids" (Anderson et al., 1999;Balme, 1995). The next chief component of the palaeoflora were non-striate bisaccate pollens of conifers (avg. ...
... These were the inconsistent member of the palaeovegetation (Fig. 8). The glossopterids along with Cordaites were the moist-loving, low-land inhabitant (swamps, flood plains, and lakes; (Traverse, 2007)) plants of the palaeovegetation and were widely distributed all along the southern hemisphere during the late Permian (Anderson et al., 1999;Balme, 1995). The conifers and peltasperms prefer to occupy drier upland areas (Kustatscher et al., 2010a;Kustatscher et al., 2010b;Kustatscher et al., 2012;Falcon, 1986). ...
The ambiguity regarding the age and palaeoecology of the Kamthi Formation is persisting for several years. In order to find the scientific answers to this problem, an integrated approach has been adopted on the samples collected from a 604 m thick sedimentary sequence (borehole) of the Kamthi Formation (late Permian), Godavari Graben. The compilation of detailed investigation includes the palynology, palynofacies and taphonomic studies, in order to establish the age, reconstructing the palaeoecology and inferring the environment of deposition. The palynological investigation indicates the presence of two informal palynoassemblages: the lower Palynoassemblage-A (Faunipollenites + Striasulcites), corresponds to the coarse-grained sandstone dominated basal part, and the Palynoassemblage-B (Densipollenites + striate bisaccates) occur in the upper fine-grained sandstone and shale dominated sequence. A detailed Gondwanan correlation of the palynoassemblages assign a late Permian age to the palynoflora: Palynoassemblage-A belongs to the Guadalupian age while Palynoassemblage-B corresponds to the Lopingian age. The dominance of glossopterids, peltasperms, conifers and Cordaites derived pollens indicate the presence of thick arborescent palaeovegetation. The rich cryptogam spore assemblage (algal, fillicopsid, and equisetopsid) constitute the opportunistic and rare component of the understorey flora. The present study suggests that the lycopsids along with few acritarchs make their appearance post-Guadalupian. The taphonomic studies infer that the palynoassemblages are greatly influenced by the structure of spores and pollen saccus. Further, the palynofacies analysis reveals a cyclic change in the environment fluctuating from unstable oxic to the stable anoxic environment. The occurrence of microscopic charcoal from the late Permian also suggests palaeo-wildfire events in the hinterland.
... Pollen fossil data showed that angiosperms were distributed worldwide about 125 Ma (Hochuli and Feist-Burkhardt, 2013), but were diverse and abundant only in the northern Gondwanan tropical areas (Schrank and Mahmoud, 2002). Prior to angiosperm dominance, a massive forest composed of gymnosperms covered India, Antarctica and Australia at least until 140 Ma (Vakhrameev, 1991;Anderson et al., 1999;Peralta-Medina and Falcon-Lang, 2012). However, the Earth climate shifted to a warming period in the mid-Cretaceous and angiosperms diversified rapidly (113 Ma), becoming the dominant plant group in the Late Cretaceous, 100 Ma (Crane, 1987;Lidgard and Crane, 1988;Lupia et al., 1999). ...
... The time of the tortricid origin and their high initial rates of diversification suggest that angiosperms were a dominant macroevolutionary driver of their diversification. Moreover, we inferred a positive shift in speciation (78 Ma, Appendix 11) when angiosperms are reported to have reached their ecological dominance in Gondwana (80 Ma; Anderson et al., 1999). This speciation shift resulted in the origin and radiation of the two species-rich subfamilies. ...
Tectonic dynamics and niche availability play intertwined roles in determining patterns of diversification. Such drivers explain the current distribution of many clades, whereas events such as the rise of angiosperms can have more specific impacts, such as on the diversification rates of herbivores. The Tortricidae, a diverse group of phytophagous moths, are ideal for testing the effects of these determinants on the diversification of herbivorous clades. To estimate ancestral areas and diversification patterns in Tortricidae, a complete tribal-level dated tree was inferred using molecular markers (one mitochondrial and five nuclear) and calibrated using fossil constraints. We found that Tortricidae diverged from their sister group c. 120 Myr ago (Ma) and diversified c. 97 Ma, a timeframe synchronous with the rise of angiosperms in the Early–mid Cretaceous. Ancestral areas analysis, based on updated Wallace's biogeographical regions, supports the hypothesis of a Gondwanan origin of Tortricidae in the South American plate. We also detected an increase in speciation rate that coincided with the peak of angiosperm diversification in the Cretaceous. This in turn probably was further heightened by continental colonization of the Palaeotropics when angiosperms became dominant by the end of the Late Cretaceous.
... The vegetation of Australia during the Late Devonian and the major part of the Mississippian is regarded as moderately diverse and dominated by small to medium-sized arborescent lycopsids (Gould, 1975;White, 1986;Anderson et al., 1999). Several successive floras were recognized based on long-term investigations of compressionimpression plant remains from eastern Australia (Morris, 1985). ...
... The anatomically-preserved taxa from Queensland might represent plants inhabiting a different type of environment than those commonly found in compression floras. This type of vegetation, described from anatomically preserved specimens, is very different from the reconstructions based on compression assemblages such as the "struggling giant clubmoss flora" of White (1986) or the "harsh landscape fringing the Gondwana icecap" of Anderson et al. (1999). ...
It is usually considered that after the extinction of the Devonian tree Archaeopteris, no new arborescent lignophytes were established before the late Tournaisian. A reassessment of this pattern is presented here based on a three-fold approach: a re-evaluation of the taxic diversity of Tournaisian lignophyte trees based on descriptions of new plants from palaeotropical latitudes, a study of the patterns of phenotypic changes occurring among early lignophytes using a principal coordinate analysis and a phylogenetic analysis of the affinities of the arborescent taxa. The best supported results indicate that a substantial taxonomic and phenotypic diversity of arborescent lignophytes was already established in the first part of the Tournaisian, including some taxa that persisted until the Serpukhovian. Two genera may have originated in the Late Devonian and crossed the Devonian–Carboniferous boundary. Fewer originations and a decrease in phenotypic diversity occurred in the Viséan. The phenotypic distinctiveness of tree stems compared with those of other growth forms in the lignophytes is assessed. We propose a scenario in which the presence of lignophyte trees is continuous across the Devonian–Carboniferous boundary, with arborescent taxa distinct from Archaeopteris already present in the latest Devonian, possibly in upland floras, and diversifying significantly soon after the Devonian–Carboniferous boundary.
... Pollen fossil data showed that angiosperms were distributed worldwide about 125 Ma (Hochuli and Feist-Burkhardt, 2013), but were diverse and abundant only in the northern Gondwanan tropical areas (Schrank and Mahmoud, 2002). Prior to angiosperm dominance, a massive forest composed of gymnosperms covered India, Antarctica and Australia at least until 140 Ma (Vakhrameev, 1991;Anderson et al., 1999;Peralta-Medina and Falcon-Lang, 2012). However, the Earth climate shifted to a warming period in the mid-Cretaceous and angiosperms diversified rapidly (113 Ma), becoming the dominant plant group in the Late Cretaceous, 100 Ma (Crane, 1987;Lidgard and Crane, 1988;Lupia et al., 1999). ...
... The time of the tortricid origin and their high initial rates of diversification suggest that angiosperms were a dominant macroevolutionary driver of their diversification. Moreover, we inferred a positive shift in speciation (78 Ma, Appendix 11) when angiosperms are reported to have reached their ecological dominance in Gondwana (80 Ma; Anderson et al., 1999). This speciation shift resulted in the origin and radiation of the two species-rich subfamilies. ...
... After the Permian, the glossopterid plants that dominated late Palaeozoic Gondwanan floras were substituted by corystosperm plants during the Triassic. According to Anderson et al. (1999), the corystosperms then constituted ca. 50% of the megafloral ratio in Gondwana floras and the proportion of conifers was lower than in both the Permian and Early Jurassic (Anderson et al., 1999). ...
... According to Anderson et al. (1999), the corystosperms then constituted ca. 50% of the megafloral ratio in Gondwana floras and the proportion of conifers was lower than in both the Permian and Early Jurassic (Anderson et al., 1999). Although conifers did not dominate during the Triassic in Gondwana, one of the voltzialean conifers, i.e., Notophytum, was probably at least as ubiquitous as corystosperms in Antarctica (Mey.-Berth. ...
During the first Korea Antarctic Geological Expedition (KAGEX I, 2013/2014), fossil wood was collected from the Triassic fluvial deposits of the Beacon Supergroup at Skinner Ridge in northern Victoria Land, Antarctica. The material is coalified and partially silicified; most specimens are slightly compressed due to burial compaction. In spite of this imperfect preservation, anatomical features of both the xylem and the pith could be observed in some specimens. The xylem displays prominent growth rings and usually araucarioid or somewhat mixed-type radial pitting with some abnormal rings partly composed of parenchymatous tissues. Some specimens also have a wood cylinder that is divided radially by parenchymatous zones. These anatomical features indicate a systematic affinity with Kykloxylon Mey.-Berth., T.N.Taylor et Ed.L.Taylor, a characteristic wood type of the Umkomaciaceae, which flourished throughout Gondwana during the Triassic. The Kykloxylon specimens in this study represent the only wood fossil taxon in the Triassic of Victoria Land, except for a dubious report of Antarcticoxylon Seward in 1914. This may indicate a low diversity of Triassic wood fossils in this area, as in other parts of Antarctica. On the contrary, diverse other gymnosperm organs are known to occur in the Triassic of Antarctica. This low diversity of wood taxa compared to the various plant organs in the Triassic of Antarctica is remarkable. We hypothesize three major reasons for this: 1) the overall structural uniformity of gymnosperm wood compared to other vegetative and especially reproductive organ diversity; 2) the overwhelming dominance of corystosperm plants, with a minor component of voltzialean conifers in the canopy-forming forest vegetation during the Triassic in Antarctica; and 3) the very few systematic studies of fossil wood compared to other plant macrofossils.
... Du Toit correlated the South African Dwyka Group (Late Carboniferous to Early Permian; Fig. 1A) glacial deposits with similar glacial deposits in Brazil (Paraná Basin), Australia (Canning Basin), and India (Talchir Basin). Dr Edna Plumstead added palaeobotanical evidence of an exclusively southern hemisphere flora, the extinct gymnosperm Glossopteris (tongue-shaped leaf) flora that occurs in the Early Permian Ecca Group, the Antarctic Transantarctic Mountains (Plumstead, 1962), the Rio Bonito Formation coals (Iannuzzi, 2010) in Brazil, the Australian Bowan and Sydney Basins (McLoughlin, 2011), and India (Anderson et al., 1999;Srivastava and Srivastava, 2016). In addition, Permian and Triassic faunal elements, such as pariasaurs (plant-eating cheek lizards) and captorhinids (primitive lizard-like reptiles; see overviews in Rubidge, 2005;and Rubidge et al., 2016) also were shown to be closely related, although preserved on seemingly distant continents today. ...
Terrestrial fossil assemblages preserved in the upper Permian–Lower Triassic strata of the Karoo Basin, South Africa, have played a central role in the interpretation of ecosystem patterns and end-Permian extinction models. However, these models need to be carefully reconsidered because of the limitations of the rock record. Four lessons learned from a multidisciplinary approach to the rocks, lithology, stratigraphy, and dating are relevant to other paleofloras in large continental basins. In reality, the Karoo paleofloral record is very sparse. Hence, reports of a near continuous fossil record in this basin should be considered as the near continuous record of erosion and time lost with sporadic plant-fossil assemblages.
A review of the debate over the rate and timing of the Permian–Triassic in the Karoo Basin reinforces the need for extensive stratigraphic mapping, the analysis of depositional environments of the plants, as well as the application of a variety of dating methods. First, Late Permian to Early Triassic paleobotanical assemblages are extremely rare in the basin with only a handful of sites in the Free State and Eastern Cape Provinces. These fossil
data originate from >3750 m of total measured section wherein megafloral remains are preserved in <1% of the available rock record (0.9% all megafloral elements; permineralized wood = 0.1%, adpressions = 0.8%), with spore-and-pollen assemblages only slightly more frequently encountered at 1.3%. This low occurrence is comparable with other basins. Thus, any continental fossil assemblage represents a very short temporal window into
the paleobiosphere because of taphonomic effects of the soils, pedogenesis, and controls on depositional environments.
Second, geochronometric and rock magnetic data, developed in a sequence stratigraphic context, are critical to constrain time and biological trends in continental successions. The missing time, diastems and hiatuses, are critically important. Third, the spatial relationships of plant-fossil assemblages are not easily correlated
across the basin without an extensive dataset of the paleolandscape. In general, the Late Permian Beaufort rocks
represent channels, floodplains, and braided streams rather than lakes and oxbows that are conducive to the preservation of plant parts. Finally, the temporal distribution of paleobotanical assemblages is complicated by the missing time (sediments) that has resulted in the apparent scarcity of vegetation before and after the end Permian extinction. The reported uncharacteristic diversity and abundance of plants in the Carnian–Norian
Molteno Formation is most likely due to an environment conducive to preserving fossil-plant assemblages combined with a record of intensive collecting. Overall, the large inland Karoo Basin, without any marine influence or extensive volcanic deposits, has favored the preservation of vertebrate assemblages.
... This climatic period coincides with the maximum diversification of the Dicroidium flora (Bomfleur et al. 2018), the second floristic event of the Cortaderitian (Spalleti et al. 2003), and the adaptive radiation of Corystospermaceae, Peltaspermaceae, and Cycadales (Anderson et al. 1999;Spalletti et al. 1999;Zamuner et al. 2001). Plant communities consisted of evergreen forests formed by corystosperms and peltasperms, with secondary elements such as conifers and ferns that characterized the fluvial areas; deciduous for-ests dominated by conifers and ginkgoales with an understory of ferns and shrubby pteridosperms associated with lacustrine margins; and herbaceous and shrubby vegetation with a dominance of sphenophytes forming cane thickets, gnetales, and pteridosperms growing in flooded lowlands (Spalleti et al. 2003;Artabe et al. 2001). ...
Body mass estimations for extinct taxa are fundamental in palaeobiological reconstructions, but little work has been
done on this topic for non-mammaliaform cynodonts (NMC), the diverse and abundant Permo-Cretaceous forerunners of
mammals. Here, we estimated the body mass of five species of NMC cynognathians by linear measurements and circumferences
of postcranial elements (humeri and femora) from 14 specimens from Triassic units of the Ischigualasto-Villa
Union Basin located between San Juan and La Rioja provinces, and the Cuyo and San Rafael basins, both in Mendoza
province, Argentina. For this purpose, we used predictive formulas available in the literature based on variables on
appendicular skeleton of different extant groups of mammals and reptiles. Geometric similarity using skull length was
applied to provide an estimation of adult masses for species with only samples of juvenile and subadult limb bones.
A broad body mass range was recorded. Small traversodontids such as Andescynodon mendozensis and Pascualgnathus
polanskii were between 1 to 3.5 kg. Medium-sized traversodontids include adult Massetognathus pascuali with masses
from 20 to 40 kg, and the adult forms of large-sized cynognathians like Cynognathus crateronotus and Exaeretodon
argentinus reached or surpassed 100 kg. The morphological variations in the skull and the different body sizes observed
between traversodontids are interpreted as reflecting different types of diets where small-sized traversodontids had a
generalist diet, and the medium/large-sized traversodontids were herbivorous. Finally, palaeoecological working hypotheses
regarding cranial and dental morphology, body mass, and their possible relation with diet in non-mammaliaform
cynodonts of South America are offered.
... In contrast, the transition from the Triassic to the Jurassic was evidenced by a mass extinction event. In Gondwana, the existence of this event is supported by the disappearance of the "Dicroidium flora", which had dominated the terrestrial landscape during most of the Triassic (Anderson et al., 1999;Kustatscher et al., 2018). Although this transition resulted in a dramatic shift in plant genera due to widespread aridity, it is thought that continental arthropods experienced few changes in their strategies for interacting with plants . ...
Interactions between the two most abundant groups of organisms on Earth, insects and plants, are especially relevant in evolutionary studies. We review different aspects related to endophytic eggs laid by insects in plants for more than 300 Myrs, from the Carboniferous to the Miocene. This work provides a meta-analysis of endophytic insect oviposition in the fossil record, based on the plant group used as host, the number of oviposition traces on a single leaf, their trace pattern, and the morphometry of the individual egg traces.
Our results show that Pinophyta and “pteridosperms” are the host-plant groups most frequently reported up to the Early Cretaceous, and Magnoliophyta (=Angiospermae) from the Cretaceous. The highest number of bibliographic records are from the Permian, while the Mesozoic Era shows the highest richness of trace patterns. No relation was detected between the trace pattern and the host-plant group used for oviposition. Our observations support the proposal that the trace pattern would be insect-specific and does not depend on the host-plant group on which the egg-laying occurs. From the Carboniferous to the Miocene, a gradual increase in the frequency of “Curved” type patterns and a decrease in “Straight” type patterns is observed. Two reduction events of the length of the traces are established, during the Permian, which could be explained by environmental causes, and during the Cretaceous by the emergence and selective predation by birds.
... The assignment of these fronds to Dicroidium based on morphology and epidermal architecture was, however, not universally accepted (e.g. Pattemore, 2016 a, b; Anderson et al., 2019a, b, c), given that the genus had before only been known from the Triassic of Gondwana (Anderson & Anderson, 1983;Anderson et al., 1999). Assignment to Dicroidium has gained further support with the recent description of the associated fertile organs. ...
The Umm Irna Formation, Jordan, holds one of the most peculiar late Permian plant–fossil assemblages worldwide. Over the last decades of field work, several localities close to the eastern shore of the Dead Sea have yielded a highly diverse ‘mixed flora’ of mesic to xeric environments encompassing elements that are typical either for different floral realms or for different time periods of Earth History. Taxa typical for particular floral realms include, e.g. Cathaysian gigantopterids and Lobatannularia, Euramerican conifers such as Otovicia hypnoides, or the characteristic Gondwanan seed ferns Glossopteris and Dicroidium. Moreover, most taxa are typical for the Permian, some assemblages have also yielded precocious occurrences of taxa that have so far been considered typical for the Mesozoic, such as Umkomasiaceae, Bennettitales, and podocarp conifers. In most cases, fossils from the Umm Irna Formation show well–preserved cuticles that allow sound systematic placement and contribute to the reconstruction of dispersed plant parts into whole–plant–taxa. Altogether, the Umm Irna Formation provides an exceptional window into depositional environments and vegetation types that are rarely preserved in the fossil record but that are crucial for our understanding of plant evolution.
... The few body fossil assemblages available seem to indicate that Early Triassic insects were mostly represented by 'survivor' taxa, i.e., groups that were present in the latest Permian but persisted with lesser diversity (Shcherbakov, 2008b). Clearly, plant and insect communities had rebounded in diversity and complexity by the Middle to Late Triassic (Anderson et al., 1999;Labandeira, 2006), but the lack of rich Early Triassic insect assemblages makes it diffi cult to directly gauge the diversity and feeding guilds of insects in the immediate aftermath of the end-Permian crisis. In the absence of body fossils, arthropod damage on fossil leaves off ers the best opportunity to assess the role of insect herbivores in the post-extinction recovery biotas. ...
An extensive survey of literature on the Permian fl oras of Gondwana reveals over 500 discrete arthropod–herbivory–damage/plant–taxon/stratigraphic–unit associations spanning all regions of the supercontinent from the earliest Asselian to the latest Changhsingian. Margin– and apex–feeding damage is the most common style of herbivory but hole– and surface–feeding, galling, and oviposition damage are locally well represented. Evidence for skeletonization and mucivory is sparse and that for leaf mining is equivocal. Wood and root boring is recognized widely but only where depositional conditions were conducive to the permineralization of plant axes. Wood boring and detritivory may have been especially favoured arthropod feeding strategies in Permian high latitudes where living foliage was scarce during the polar winters. Herbivory damage is most strongly apparent on glossopterid remains; other groups of broad–leafed gymnosperms and sphenopsids host moderate levels of damage. Damage features are under–represented on lycophytes, ferns and spine– and scale–leafed conifers. A survey of insect body fossils from the Gondwanan Permian reveals that most records are from a small number of rich assemblages that are dominated by Blattodea, Hemiptera, Grylloblattida, Mecoptera and Protelytroptera, accompanied by signifi cant representations of Coleoptera, Glosselytrodea, Miomoptera, Neuroptera, Odonata, Protorthoptera, Palaeodictyopteroida, Paoliida, Paraplecoptera, Plecoptera, Psocoptera,
Thysanoptera and Trichoptera, which collectively adopted a broad range of feeding styles. Oribatid mites and collembolans appear to have been important components of the wood–boring and detritivorous communities. Although temporal trends in herbivory styles and diversity are diffi cult to resolve from mostly incidental observations and illustrations of plant damage across Gondwana, the results of this study provide a baseline of qualitative data for future studies that should adopt a quantitative approach to the analysis of herbivory, spanning the shift from icehouse to hothouse conditions through the Permian of the Southern Hemisphere.
... It is worth mentioning that during the Permian, a great number of Lycopsida species, together with several other tracheophytes, became extinct because of a marked tendency towards aridity on Pangaea North 1991a, 1991b;Anderson et al. 1999;Fanton et al. 2006). The objective of this work is the descriptive analysis of a plant fossil assemblage focusing on the morphological description of the preserved stems found in an outcrop near Rio Claro city, São Paulo State (Brazil). ...
The Permian lycopsid Lycopodiopsis derbyi Renault, 1890 (Lemoigne and Brown 1980) Faria et al. (2009) is an abundant plant that inhabited the margins of the Paraná Basin under semi-arid and sometimes hypersaline environmental conditions of late Permian. Here we study a remarkable and unprecedented assemblage, with stems attributed to Lycopodiopsis cf. derbyi Renault preserved in an outcrop in the Rio Claro municipality, São Paulo State, Brazil. The stems are preserved in the north-south orientation, spreading over a wide area with a massive concentration of overlapping specimens, thus forming a monospecific plant fossil assemblage. The stems are unbranched or dichotomously branching, preserved as compression-impressions and cast. In the preserved assemblage, there are records of at least three different cortical levels which may be associated with Lycopodiopsis cf. derbyi. This record is possibly non-selective. Lycopodiopsis cf. derbyi commonly occurs in the Passa Dois Group, indicating it was an important component of the southwestern Gondwana coastal floodplains flora, which today constitutes São Paulo State and Southern Brazil.
... Palaeofloras recovered from these three units correspond to Dicroidium Flora characterized by the dominance of pteridosperms referred to the Gondwanan endemic family Umkomasiaceae (Balme & Helby 1973;Zamuner et al. 2001;Mays & Mcloughlin 2019). These association also includes cosmopolitan taxa referred to Equisetales (Neocalamites), Osmundales (Cladophlebis), Peltaspermales (Lepidopteris, Scytophyllum), Cycadales (Ctenis), Bennettitales (Pterophyllum, Anomozamites), Ginkgoales (Baiera, Sphenobaiera) and Voltziales (Heidiphyllum) (Anderson & Anderson 1983;Anderson et al. 1999;Spalletti et al. 1999;Artabe et al. 2001;Zamuner et al. 2001;Kustatscher et al. 2018;Stipanicic & Archangelsky 2002;Lutz et al. 2011;Ottone et al. 2011;Chatterjee et al. 2013;Mcloughlin 2001;Pedernera et al. 2019Pedernera et al. , 2020a) (supplementary information Table S1). ...
The impact of volcanic activity and trophic state on the preservation of plant remains from two Triassic palaeolake deposits in western Gondwana is investigated. Six taphonomic modes are identified for the Potrerillos–Cacheuta sequence and the Los Rastros Formation, along with proposed taphonomic pathways for each mode. The taphonomic pathways were compared with those proposed for the Agua de la Zorra Formation, a coeval lacustrine‐deltaic succession. In all three cases, plant preservation in off‐shore lacustrine facies was enhanced by anoxic bottom conditions. In the more proximal near‐shore facies, a high sedimentation rate would have been factor that enhanced the preservation. Variation in relative abundance and taxonomic diversity between the three successions are attributed to ecological differences rather than taphonomic differences among the lake systems. No evidence was recorded that the preserved plant material was produced by volcanic trauma. The preservation of the cuticle recorded in the Cacheuta Formation was likely enhanced by the apparently low thermal maturation of the rock and the presence of tuffaceous horizons. In the three successions, the abundance and distribution of remains throughout the sections suggest that the trophic state of the lake did not influence the preservation of the plant.
... The radiation of gymnosperms is not comparable to the massive radiation observed after the Permian-Triassic extinction event. However, rise and diversification of cheirolepidacean conifers, caytoniales and seed-ferns is observed (Anderson et al. 1999). ...
Upper Gondwana deposits occur extensively across peninsular and extra-peninsular parts of India. The present study provides a critical palynological review of the Indian Upper Gondwana sequence, mainly focusing on the paleobotanical distribution, diversity, and transitions. The current problems and stratigraphic lacuna in dating and correlating the Upper Gondwana sequence of India are also discussed. The palynological data pertaining to the Jurassic and Cretaceous periods of Gondwana reveals the presence of four phases of floral transition, i.e., (I) the Triassic-Jurassic boundary flora (replacement of corystosperms by cheirolepidacean conifers); (II) the post-Toarcian flora (replacement of cheirolepidacean conifers by araucarian conifers); (III) the Tithonian-Valanginian flora (rise of araucarians and podocarps; (IV) the post-Hauterivian flora (appearance of angiosperms). These floral transitions were greatly affected by tectonic movements and eustatic changes. The palynostratigraphic correlation of Indian flora with other contemporaneous strata across the Gondwana continents shows its close similarity with eastern Antarctica and Australia constituting a single phytogeographic province.
... Especially the latter are of great interest because they include several species of Dicroidium (Kerp et al., 2006), a seed fern from the group of the corystospermales with distinctive forked leaves. Dicroidium is traditionally considered to be typical for the Triassic of Gondwana (Anderson et al., 1999) where it replaced the glossopterids. The Jordan occurrence of Dicroidium predates its "traditional" Triassic occurrences in central and southern Gondwana and is located much further to the north. ...
The greening of our planet is a fascinating story. The vast majority of the Earth's biomass is produced by plants, ranging from microscopically small phytoplankton to complex rainforest ecosystems. The evolution of plants can be traced back to the Archean and is intrinsically connected with the evolution of the Earth's geosphere and atmosphere.
... This latter group came to dominate the lowland vegetation of not only the Australian continent but extended its biogeographic range into the middle to high latitudes of the rest of Gondwana. It dominated the Southern Hemisphere floras for the remainder of the Permian (Anderson et al. 1999). The earliest Permian vegetation of Australia has been interpreted as an analog of modern tundra because of its monotonous herbaceous groundcover interspersed with sparse, dwarfed woody shrubs. ...
The assembly of the supercontinent Pangea resulted in a paleoequatorial region known as Euramerica, a northern mid-to-high latitude region called Angara, and a southern high paleolatitudinal region named Gondwana. Forested peat swamps, extending over hundreds of thousands of square kilometers, grew across this supercontinent during the Mississippian, Pennsylvanian, and Permian in response to changes in global climate. The plants that accumulated as peat do not belong to the plant groups prominent across today’s landscapes. Rather, the plant groups of the Late Paleozoic that are responsible for most of the biomass in these swamps belong to the fern and fern allies: club mosses, horsetails, and true ferns. Gymnosperms of various systematic affinity play a subdominant role in these swamps, and these plants were more common outside of wetland settings. It is not until the Permian when these seed-bearing plants become more dominant. Due to tectonic activity associated with assembling the supercontinent, including earthquakes and volcanic ashfall, a number of these forests were buried in their growth positions. These instants in time, often referred to as T⁰ assemblages, provide insight into the paleoecological relationships that operated therein. Details of T⁰ localities through the Late Paleozoic demonstrate that the plants, and plant communities, of the coal forests are non-analogs to our modern world. Analysis of changing vegetational patterns from the Mississippian into the Permian documents the response of landscapes to overall changes in Earth Systems under icehouse to hothouse conditions.
... During the Middle to Late Triassic, Gondwana was dominated by the 'Dicroidium Flora' (Balme and Helby, 1973;Zamuner et al., 2001;Mays and Mcloughlin, 2019), characterized by the dominance of pteridosperms referred to the Gondwanan endemic family Umkomasiaceae. This association also includes cosmopolitan taxa referred to Equisetales (Equisetites, Neocalamites), Lycopsida (Pleuromeia), Osmundales (Cladophlebis), Peltaspermales (Lepidopteris, Scytophyllum), Cycadales (Ctenis), Bennettitales (Pterophyllum, Anomozamites), Ginkgoales (Ginkgoites, Baiera, Sphenobaiera) and Voltziales (Heidiphyllum) (Anderson and Anderson, 1983;Anderson et al., 1999;Spalletti et al., 1999;Artabe et al., 2001;Mcloughlin, 2001;Zamuner et al., 2001;Stipanicic and Archangelsky, 2002;Chatterjee et al., 2013;Kustatscher et al., 2018). ...
The Los Rastros Formation was deposited in a deltaic-lacustrine environment during the Late Triassic. Plant remains from the Gualo area were systematically collected and compared with other localities from the Los Rastros Formation concerning the sedimentary evolution of the basin. Subsequently, the Los Rastros paleoflora was contrasted with other Carnian (Upper Triassic) units from Gondwana in a paleobiogeographic context using statistical methodologies: Raup-Crick similarity index and hierarchical cluster analysis. The systematic study revealed 14 taxa for the Los Rastros Formation at the Gualo area. Plant vegetative remains of Equisetales (Neocalamites sp.), Osmundaceae (Cladophlebis sp. cf. C. mesozoica), Umkomasiales (Dicroidium odontopteroides, Johnstonia stelzeriana, Xylopteris argentina, X. elongata, and Zuberia feistmantelii), Ginkgoales (Baiera pontifolia, Sphenobaiera sp. cf. S. argentinae), Voltziales (Heidiphyllum elongatum), Coniferales (Rissikia media), and gymnospermous reproductive structures (Cordaicarpus sp., Samaropsis sp. and strobilus sp. A). The stratigraphic distribution of taxa throughout the Los Rastros Formation in the Gualo section is variable. Diminution of taxa recorded observed across the section could be explained by the isolation of the paleolake product of the activity of a secondary fault. The plant taxa registered at the different localities of the Los Rastros Formation could be related to the location of each locality in the basin and the different depositional conditions during the infill history of the basin at each locality. Comparison among Los Rastros Formation plant records with other paleofloras from Gondwana by statistical analyses indicates differences with respect to a previous paleobiogeographic proposal.
... The third Florian Stage or DML Biozone of the Late Triassic (Norian to ?Rhaetian) (Spalletti, 1997;Artabe et al., 1998;Spalletti et al., 1999;Morel et al., 2003) where the Tronquimalal Group is included, shows substantial changes in plant composition of communities of the long-lasting endemic Triassic Dicroidium-dominated floras. During the Florian event, Corystospermaceae, Peltaspermaceae, and ginkgoaleans declined while some taxa became dominant during the Jurassic across the Southern Hemisphere (Anderson and Anderson, 1993;Anderson et al., 1999;Spalletti et al., 1999;Zamuner et al., 2001;Morel et al., 2003), such as conifers and bennettitaleans (McLoughlin, 2001). Thus, the Florian Stage shows the development of deciduous forests where the corystosperms disappeared from the arboreal stratum . ...
Late Triassic coniferous species of silicified woods are described from the Tronquimalal Group, Llantenes Depocenter of the Neuquén Basin, southern Mendoza Province, Argentina. The new species Agathoxylon cozzoi and Agathoxylon lamaibandianus Crisafulli and Herbst, 2011 described in this study were found in proximal volcaniclastic facies deposited in alluvial fans and proximal braided river plains of the Chihuido Formation, which is the basal unit of the Group. The species A . lamaibandianus Crisafulli and Herbst, Protojuniperoxylon ischigualastense (Bonetti, 1966) Bodnar and Artabe, 2007, and the new species Cupressinoxylon llantenesense also described in this study were collected from the upper fluvio-deltaic plain and delta-plain deposits that prograded into a large, meromictic and wedge-shaped lake of the overlying Llantenes Formation. The Tronquimalal Group yields abundant and well-known Triassic plant remains of the Southern Gondwana “ Dicroidium Flora,” although it also contains typical early Jurassic taxa displaying age affinities with other Argentinean “Florian Stage” communities of Late Triassic (Norian–?Rhaetian). The lignotaxa described from both units of the Tronquimalal Group may all together represent coniferous forests of the extratropical area of the Southwestern Province of Gondwana. Deciduous conifer forests associated with herbaceous and shrub communities dominated by ferns and smaller corystosperms, and other taxa including the Linguifolium leaves within the Llantenes Depocenter environments, were developed on the western margin of the continent under seasonal temperate-warm and humid to sub-humid climate with a marine influence from the west.
... From a physiognomic point of view, Pampa has few trees, while Campos includes gallery forests along rivers and woodlands dispersed on hilly areas (Soriano et al., 1992). From a geomorphology standpoint, the Pampa has been formed by thick quaternary loess deposits that have experienced varying degrees of local reworking (Anderson et al., 1999;Ortiz-Jaureguizar and Cladera, 2006). Exceptions to this general pattern are a few isolated uplands in Argentina. ...
Temperate subhumid grasslands extend in the eastern part of South America. This region represents one of the most diverse, largest and less transformed grassland areas in the world. The grasslands occupy the vast and continuous plains of central-eastern Argentina, Uruguay and southern Brazil that surround the Río de la Plata estuary. For this reason, they are referred to as the Río de la Plata grasslands. These grasslands, despite its apparent physiognomic homogeneity, hold high diversity of species, having grasses as the dominant life form except for few scattered shrubs and trees, and show a year-round photosynthetic activity. In this article we describe structural and functional characteristics of the vegetation of the Río de la Plata grasslands. We give an overview on biogeography, ecosystem functioning and services, human appropriation of primary production, disturbances, land use change, biological invasions and conservation status.
... 1996;Visscher et al., 1996). The extinction may have started an unparalleled, explosive, gymnosperm radiation in the earliest Triassic (Retallack, 1997a), though this is based on extrapolation from relatively few studies (Anderson et al., 1999). The detailed studies required for evaluation of competing hypotheses of extinction and evolution available from some marine sections throughout the world are not matched by similar studies in non-marine sections. ...
... However, their pattern of diversification in other regions of the world remains obscure owing to the paucity of well-documented specimens from this period. For the supercontinent Gondwana, the most recent general synthesis (Anderson et al., 1999) suggested a significant delay in diversification of seed plants and ferns compared to the northern continents. However, recent studies suggest that these plant groups were present in Gondwana earlier than inferred, at least in the paleotropics (see Prestianni et al., 2015 for a discussion of high-latitude floras). ...
Early Carboniferous (Mississippian) permineralized woods from Australia with multiseriate rays have been customarily assigned or compared to the European genus Pitus, despite the absence of information on their primary vascular anatomy. In the context of continuing work on the diversity of Late Devonian and Mississippian floras of Gondwana, we studied new silicified woods with secondary xylem similar to that of Pitus (multiseriate rays, araucarioid radial pitting) from two sedimentary basins of Queensland, Australia. In the Drummond Basin, three morphotypes of wood of Viséan age can be distinguished based on ray size in tangential section. Although this variation is similar to that observed between the various European species of Pitus, information on the primary vascular anatomy of the trees provided by three incomplete specimens excludes an affinity with Pitus for at least two taxa. In the Yarrol Basin, two well-preserved late Viséan trunks also have characters similar to Pitus but can be distinguished from that genus and other previously described Mississippian trees, in particular by the anatomy of their primary vascular system and departing leaf traces. They are assigned to a new genus, Ninsaria. Collectively, the new specimens from Queensland show that wood traditionally referred to “Pitus” from Australia actually belongs to several other types of trees that are not known from Europe or North America, indicating probable floristic provincialism between the Northern and Southern hemisphere floras at this time. These new fossils corroborate the existence of a global Mississippian diversification of (pro)gymnosperm trees already noted in Laurussia. They also indicate that the Mississippian floras of Australia were more diverse and complex than traditionally inferred.
... However, their pattern of diversification in other regions of the world remains obscure owing to the paucity of well-documented specimens from this period. For the supercontinent Gondwana, the most recent general synthesis (Anderson et al., 1999) suggested a significant delay in diversification of seed plants and ferns compared to the northern continents. However, recent studies suggest that these plant groups were present in Gondwana earlier than inferred, at least in the paleotropics (see Prestianni et al., 2015 for a discussion of high-latitude floras). ...
Early Carboniferous (Mississippian) permineralized woods from Australia with multiseriate rays have been customarily assigned or compared to the European genus Pitus, despite the absence of information on their primary vascular anatomy. In the context of continuing work on the diversity of Late Devonian and Mississippian floras of Gondwana, we studied new silicified woods with secondary xylem similar to that of Pitus (multiseriate rays, araucarioid radial pitting) from two sedimentary basins of Queensland, Australia. In the Drummond Basin, three morphotypes of wood of Viséan age can be distinguished based on ray size in tangential section. Although this variation is similar to that observed between the various European species of Pitus, information on the primary vascular anatomy of the trees provided by three incomplete specimens excludes an affinity with Pitus for at least two taxa. In the Yarrol Basin, two well-preserved late Viséan trunks also have characters similar to Pitus but can be distinguished from that genus and other previously described Mississippian trees, in particular by the anatomy of their primary vascular system and departing leaf traces. They are assigned to a new genus, Ninsaria. Collectively, the new specimens from Queensland show that wood traditionally referred to “Pitus” from Australia actually belongs to several other types of trees that are not known from Europe or North America, indicating probable floristic provincialism between the Northern and Southern hemisphere floras at this time. These new fossils corroborate the existence of a global Mississippian diversification of (pro)gymnosperm trees already noted in Laurussia. They also indicate that the Mississippian floras of Australia were more diverse and complex than traditionally inferred.
... During the Triassic, Gondwana floras were dominated by corystosperms which were the successful successors of glossopterids in the Permian (Anderson et al., 1999). They were the major component of the canopy-forming forest vegetation in Antarctica with other minor components, e.g., the voltzialean conifers (Bomfleur et al., 2013;Oh et al., 2016). ...
During the 2016 Antarctic summer season, the fourth Korea Antarctic Geological Expedition (KAGEX IV) investigated the Ricker Hills in southern Victoria Land, Antarctica and collected 33 specimens of fossil wood from an outcrop of Triassic Beacon sandstone in a small basin, Ricker Hills area. Based on anatomical features, four specimens can be identified as belonging to the seed-fern wood Kykloxylon sp. (Corystospermales). A specimen is identified as Agathoxylon sp. and it is the first report of the genus from the Triassic deposits in Victoria Land, Antarctica. We are able to reconfirm that corystosperm trees were a dominant component of the Triassic forest vegetation in Antarctica, with minor occurrences of Agathoxylon trees of yet uncertain affinities from those results. In addition, the new occurrence of Agathoxylon at the Ricker Hills also shows us that there is still a shortage of fossil wood studies in Victoria Land.
... в [Го маньков, Мейен, 1986]), в меньшей степени - флор Северной Евразии [Могучева, Наугольных, 2010] и Китая [Yang et al., 1986;Wang, 1993Wang, , 1996aWang, , 1996b. Большой массив литературы сфокусиро ван на переходе от палеозойских флор к мезо зойским в Гондване [Retallack, 1980;McLoughlin et al., 1997;Pal, Ghosh, 1997;Anderson et al., 1999;Retallack, Krull, 1999;Chandra et al., 2008;Singh et al., 2012]. ...
The monograph deals with the Permian flora of Western Angaraland (Middle and South Cis-Urals) with involving of some
data from adjacent regions (the Pechora Cis-Urals, central regions of Angaraland). Information about the localities studied
with layer-by-layer description of the most important geological sections (Taezhnoe-1, Chekarda-1), as well as the lists of plant
megafossils are given. History of study of the Upper Palaeozoic plants of Russia with special reference to the Cis-Urals localities
is discussed. The special chapter is devoted to a description of higher fossil plants. This chapter includes the data on all
the most important plant groups which are characteristic of the Permian deposits of the Cis-Urals: lycopodiopsids,
sphenophylls, calamites, equisetophytes, ferns, pteridosperms, ginkgophytes, vojnovskyans, and conifers. Several taxa are
described for the first time. Author’s viewpoint on the palaeoecological reconstructions of Permian floras of the Cis Urals is
presented in conclusive part of the monograph.
The book is aimed for palaeontologists, stratigraphers, and all the persons who are interested in problems of the
evolution of the Organic World of the Earth.
... All frond forms, however, possess the characteristic basal bifurcation (see Anderson and Anderson, 1983), share distinctive epidermal and cuticular features (e.g., Gothan, 1912;Thomas, 1933;Jacob and Jacob, 1950;Townrow, 1957;Archangelsky, 1968;Bomfleur and Kerp, 2010), and are associated with similar reproductive organs (e.g., Thomas, 1933;Anderson and Anderson, 1983). The Dicroidium seed ferns were the dominant gymnosperm group in temperate forest and wetland environments across most of the Southern Hemisphere during the Middle and Late Triassic (e.g., Anderson et al., 1999;McLoughlin, 2001). Owing to their ubiquitous occurrence and sheer abundance in the Gondwanan Triassic, the informal term "Dicroidium flora" is commonly used to describe their main geographic and biostratigraphic realm (e.g., Hirmer, 1936;Townrow, 1957;Barnard, 1973;Gould, 1975;McLoughlin, 2001;Artabe et al., 2003). ...
A permineralized seed, Pachytestopsis tayloriorum gen. et sp. nov., is described from the Changhsingian (upper Permian) Fort Cooper Coal Measures at the Homevale locality in the northern Bowen Basin, Queensland, Australia. This largest permineralized seed species yet recorded from Permian deposits of Gondwana conforms to a size accommodated by either Rigbyaceae or Lidgettoniaceae (glossopterid) fructifications recorded elsewhere in the Sydney-Bowen basin complex. The seeds are characterized by a thin endotesta of longitudinally orientated cells, thick mesotesta incorporating an inner band of very thick walled sclereids and an outer layer of thin-walled parenchymatous cells, and an exotesta that comprises a well-developed epidermis and several layers of thick-walled hypodermal cells. Vascular supply to the base of the seed passes through the integument and bifurcates into the nucellar pad. Taeniate bisaccate pollen of Protohaploxypinus-type occurs in the pollen chamber of the seed. A comparison of the characters of P. tayloriorum with other permineralized seeds from the Permian of Gondwana indicates that several of the characters used in previous phylogenetic analyses incorporating glossopterids are wrongly scored or ambiguous in their definition.
... All frond forms, however, possess the characteristic basal bifurcation (see Anderson and Anderson, 1983), share distinctive epidermal and cuticular features (e.g., Gothan, 1912;Thomas, 1933;Jacob and Jacob, 1950;Townrow, 1957;Archangelsky, 1968;Bomfleur and Kerp, 2010), and are associated with similar reproductive organs (e.g., Thomas, 1933;Anderson and Anderson, 1983). The Dicroidium seed ferns were the dominant gymnosperm group in temperate forest and wetland environments across most of the Southern Hemisphere during the Middle and Late Triassic (e.g., Anderson et al., 1999;McLoughlin, 2001). Owing to their ubiquitous occurrence and sheer abundance in the Gondwanan Triassic, the informal term "Dicroidium flora" is commonly used to describe their main geographic and biostratigraphic realm (e.g., Hirmer, 1936;Townrow, 1957;Barnard, 1973;Gould, 1975;McLoughlin, 2001;Artabe et al., 2003). ...
Throughout Earth history, plants were apparently less dramatically affected by global biotic crises than animals. Here, we present the unexpected occurrence of Dicroidium, the iconic plant fossil of the Gondwanan Triassic, in Jurassic strata of East Antarctica. The material consists of dispersed cuticles of three Dicroidium species, including the type species D. odontopteroides. These youngest occurrences complement a remarkable biogeographic pattern in the distribution of Dicroidium through time: the earliest records are from palaeoequatorial regions, whereas the last records are from polar latitudes. We summarize similar, relictual high-latitude occurrences in other plant groups, including lycopsids, various ‘seed ferns’, Bennettitales, and cheirolepid conifers, to highlight a common phenomenon: during times of global warmth, the ice-free high-latitude regions acted as refugia for relictual plant taxa that have long disappeared elsewhere. Eventually, such last surviving pPolar populations probably disappeared as they became outcompeted by newly emerging plant groups in the face of environmental change.
... In the Early Cretaceous, the Gondwana rifting process made small rifts in Northeastern Brazil, capturing the drainage system waters and forming lakes (Carvalho and Melo, 2012). These lakes occupied regions of low latitude and were subjected to arid conditions during the transition from a moderate icehouse to greenhouse condition (Anderson et al., 2007(Anderson et al., , 1999Frakes et al., 1992;Scotese et al., 1999), which are documented in siliciclastic rocks (Françolin and Szatmari, 1987;Rocha and Amaral, 2006) in the Sousa Basin, located in the State of Paraíba (Fig. 1). The basin was filled with sediments deposited in fluvio-lacustrine environments, successively represented by the Antenor Navarro (sandstones and conglomerates), Sousa (mudstones) and Rio Piranhas (sandstone and conglomerates) formations included in the Rio do Peixe Group (Albuquerque, 1986). ...
In the beginning of Gondwana's break up, small rift lakes were formed in the area that is nowadays located in Northeastern Brazil. These lakes captured the drainage systems and were subjected to hot and arid climatic conditions in a low-latitude area. These conditions are evidenced by the Lower Cretaceous fluvio-lacustrine deposits that filled the Sousa Basin, which integrates a complex of basins along the Rio do Peixe (State of Paraíba). The Sousa Formation is the most representative unit in the Sousa Basin, being predominantly composed of siltstones and shales deposited in shallow lacustrine environments with fluvial influence. The sedimentation occurred under a semi-arid climate with alternating rainy and dry seasons, indicating the presence of ephemeral lakes. This is also supported by the lithology, the sedimentary structures (mud cracks) and the evaporites (gypsum). The lacustrine environment is favorable to the proliferation of non-marine ostracods, which are microcrustaceans of great importance for the study of current and paleolake deposits. Non-marine ostracod assemblages recovered from the Sousa Formation, sampled from core 2-FC-1-PB, revealed undescribed species. In this work, these ostracods were studied taxonomically, with the new species Cypridea paraibensis sp. nov., Cypridea vianai sp. nov. and Alicenula sousaensis sp. nov., as well as the already described Alicenula leguminella (Forbes, 1855) Martens, Rossetti and Horne 2003, Brasacypris ovum Krömmelbein 1965, Cypridea ambigua Krömmelbein 1962, and Reconcavona swaini Krömmelbein 1962 being identified. Another set of taxa remained in open nomenclature, since the morphological descriptions did not fit existing species. Thus, the descriptions referring to the described groups take into consideration criteria such as similarity and variability of morphological factors (Alicenula ex gr. leguminella and Alicenula sp. 1), degree of preservation, and quantity of recovered carapaces.
... In response, pteridosperm diversity diminished and several groups became extinct towards the conclusion of this interval (McLoughlin et al. 2010). The rise of the angiosperms during the mid-Cretaceous was a major turning point in the vegetation history of the world, and most younger floras, including those of southern Gondwana, are dominated by this group (Anderson et al. 1999, Friis et al. 2011. ...
Although Cretaceous fossils (coal excluded) from Victoria, Australia, were first reported in the 1850s, it was not until the 1950s that detailed studies
of these fossils were undertaken. Numerous fossil localities have been identified in Victoria since the 1960s, including the Koonwarra Fossil
Bed (Strzelecki Group) near Leongatha, the Dinosaur Cove and Eric the Red West sites (Otway Group) at Cape Otway, and the Flat Rocks site
(Strzelecki Group) near Cape Paterson. Systematic exploration over the past five decades has resulted in the collection of thousands of fossils representing
various plants, invertebrates and vertebrates. Some of the best-preserved and most diverse Hauterivian–Barremian floral assemblages in
Australia derive from outcrops of the lower Strzelecki Group in the Gippsland Basin. The slightly younger Koonwarra Fossil Bed (Aptian) is a
Konservat-Lagerstätte that also preserves abundant plants, including one of the oldest known flowers. In addition, insects, crustaceans (including
the only syncaridans known from Australia between the Triassic and the present), arachnids (including Australia’s only known opilione), the stratigraphically
youngest xiphosurans from Australia, bryozoans, unionoid molluscs and a rich assemblage of actinopterygian fish are known from the
Koonwarra Fossil Bed. The oldest known—and only Mesozoic—fossil feathers from the Australian continent constitute the only evidence for tetrapods
at Koonwarra. By contrast, the Barremian–Aptian-aged deposits at the Flat Rocks site, and the Aptian–Albian-aged strata at the Dinosaur
Cove and Eric the Red West sites, are all dominated by tetrapod fossils, with actinopterygians and dipnoans relatively rare. Small ornithopod
(=basal neornithischian) dinosaurs are numerically common, known from four partial skeletons and a multitude of isolated bones. Aquatic meiolaniform
turtles constitute another prominent faunal element, represented by numerous isolated bones and articulated carapaces and plastrons. More
than 50 specimens—mostly lower jaws—evince a high diversity of mammals, including monotremes, a multituberculate and several enigmatic
ausktribosphenids. Relatively minor components of these fossil assemblages are diverse theropods (including birds), rare ankylosaurs and ceratopsians,
pterosaurs, non-marine plesiosaurs and a lepidosaur. In the older strata of the upper Strzelecki Group, temnospondyl amphibians—the youngest
known worldwide—are a conspicuous component of the fauna, whereas crocodylomorphs appear to be present only in up-sequence deposits of
the Otway Group. Invertebrates are uncommon, although decapod crustaceans and unionoid bivalves have been described. Collectively, the Early
Cretaceous biota of Victoria provides insights into a unique Mesozoic high-latitude palaeoenvironment and elucidates both palaeoclimatic and
palaeobiogeographic changes throughout more than 25 million years of geological time.
... Both Jurassic floras lack flowering plants, whereas each of the Early Cretaceous floras contains the earliest records of angiosperms from the respective regions. This interval also witnessed active breakup of the gondwanan continents, progressive isolation of southeast Australian biotas at middle to high southern latitudes, and significant floristic turnovers in both regions (Vakhrameev, 1991;Anderson et al., 1999;McLoughlin, 2001;Laurie et al., 2012). We aim to compare and contrast the disseminule assemblages to identify any patterns in the representation of plant propagule types through time in each region and on either side of the Neotethys Ocean. ...
Four upper Middle Jurassic to Lower Cretaceous lacustrine Lagerstätten in China and Australia (the Daohugou, Talbragar, Jehol, and Koonwarra biotas) offer glimpses into the representation of plant disseminule strategies during that phase of Earth history in which flowering plants, birds, mammals, and modern insect faunas began to diversify. No seed or foliage species is shared between the Northern and Southern Hemisphere fossil sites and only a few species are shared between the Jurassic and Cretaceous assemblages in the respective regions. Free-sporing plants, including a broad range of bryophytes, are major components of the studied assemblages and attest to similar moist growth habitats adjacent to all four preservational sites. Both simple unadorned seeds and winged seeds constitute significant proportions of the disseminule diversity in each assemblage. Anemochory, evidenced by the development of seed wings or a pappus, remained a key seed dispersal strategy through the studied interval. Despite the rise of feathered birds and fur-covered mammals, evidence for epizoochory is minimal in the studied assemblages. Those Early Cretaceous seeds or detached reproductive structures bearing spines were probably adapted for anchoring to aquatic debris or to soft lacustrine substrates. Several relatively featureless seeds in all assemblages were potentially adapted to barochory or to endozoochory-the latter evidenced especially by the presence of smooth seeds in vertebrate gut contents and regurgitant or coprolitic masses. Hydrochory is inferred for several aquatic plants that notably bear small featureless seeds, particularly aggregated into detachable pods.
... Permian continental deposits from the palaeoequatorial regions of Pangaea, however, contain ''mixed floras'' with co-occurrences of plant fossils that are typical of different floral provinces (e.g., Wagner 1962;Berthelin et al. 2003). Of special importance is the Permian Um Irna Formation of Jordan, which has yielded rich assemblages of mummified plant compressions (e.g., Bandel and Khoury 1981;Makhlouf et al. 1991;Mustafa 2003;Abu Hamad 2004;Abu Hamad et al. 2008;Kerp et al. 2006) dominated by the seed-fern frond Dicroidium-a genus traditionally thought to occur only in the Gondwanan Triassic (Anderson et al. 1999). Previous studies have shown that also floral elements of other palaeobiogeographic provinces of Pangaea occur in the Um Irna Formation (Mustafa 2003). ...
Dicroidium bandelii sp. nov. (Corystospermales) is described from the Um Irna Formation (Permian) of the Dead Sea Region, Jordan. The type and only specimen is a compressed frond fragment with cuticle. The new species is unique in showing pinnate frond architecture with elongate, lanceolate pinnae with a dense, near-parallel venation. In situ epifluorescence-microscopic analysis of the cuticle revealed evenly distributed, superficial stomata with differentiated lateral subsidiary cells typical of the genus. Epidermal and cuticular features readily distinguish D. bandelii from some superficially similar species of Ptilozamites or Thinnfeldia. Our report demonstrates that the diversity of Corystospermales in the unusual ‘mixed flora’ of the Permian palaeotropics is still greater than previously thought, and that the Um Irna Formation in particular holds a great potential for future palaeontological research.
... However, bennettitalean affinities have not been confirmed for any of these leaves by cuticular details (Pott et al. 2010b). Bennettitales died out in most parts of the world by the end of the Cretaceous (Watson and Sincock 1992;Anderson et al. 1999; This article is a contribution to the special issue "Jurassic biodiversity and terrestrial environments" et al. 2010a, 2014), although at least one taxon appears to have persisted in high-latitude refugia of Tasmania and eastern Australia until the Oligocene . ...
Several dispersed reproductive organs of bennettitopsid gymnosperms are described and illustrated from Triassic to Cretaceous strata of Australia: Williamsonia eskensis sp. nov. (Middle Triassic), Williamsonia ipsvicensis sp. nov. (Upper Triassic), Williamsonia durikaiensis sp. nov. (Lower Jurassic), Williamsonia sp. (Lower Jurassic), Williamsonia rugosa sp. nov. (Middle Jurassic), Williamsonia gracilis sp. nov. (Lower Cretaceous), Cycadolepis ferrugineus sp. nov. (Lower Jurassic), Cycadolepis sp. (Lower Cretaceous), and Fredlindia moretonensis Shirley 1898 comb. nov. (Upper Triassic). Among these, W. eskensis appears to represent the oldest bennettitalean reproductive structure yet identified. Although global floras expressed less provincialism during the Mesozoic and many genera are cosmopolitan, Australian bennettopsid species appear to have been endemic based on the morphological characters of the reproductive structures. Bennettopsids have a stratigraphic range of around 210 million years in Australia and are widely and abundantly represented by leaf fossils, but only around 20 specimens of reproductive structures, of which half are attributed to Fredlindia, have been recovered from that continent’s geological archive. The extremely low representation of reproductive organs vis-à-vis foliage is interpreted to reflect a combination of physical disintegration of the seed-bearing units while attached to the host axis and, potentially, extensive vegetative reproduction in bennettopsids growing at high southern latitudes during the Mesozoic.
... The Early Carboniferous (Mississippian) floras of Gondwana have been traditionally reconstructed as low diversity and dominated by arborescent lycopsids (e.g., Anderson et al., 1999). While work by Iannuzzi and Pfefferkorn (2002) has provided more information on the floras of Gondwana's warm temperate belt (30°S-60°S) during the late Visean to earliest Serpukhovian, our knowledge of the composition and distribution of Gondwana floras during the Early Mississippian (Tournaisian) remains noticeably scarce. ...
A new taxon of lignophyte is described based on a permineralized stem from the Late Tournaisian (Lower Carboniferous) of the Central Ahnet region, Algeria. It shows similarities with arborescent seed plants described in the Lower Carboniferous of Europe and North America such as Eristophyton waltonii Lacey and Cauloxylon ambiguum Cribbs. However, the primary and secondary vascular system of the stem display an original combination of characters and it is assigned to a new genus: Ahnetia. The preservation of extraxylary tissues (secondary phloem, periderm, cortex) allows formulating hypotheses on the stem's growth potential. The early appearance of a periderm indicates that Ahnetia was capable of significant secondary growth and that the specimen likely represents a young axis of a larger plant. By its Late Tournaisian age, this specimen represents the oldest known occurrence in North Africa of a lignophyte capable of significant secondary growth after the extinction of the progymnosperm Archaeopteris.
http://www.sciencedirect.com/science/article/pii/S0034666716300124
... According to dated phylogenies, leafy liverworts (Jungermanniidae) might have been established in the late Carboniferous, and have split into the two main lineages, Porellales and Jungermanniales, during Early-Middle Permian (Cooper, Henwood, & Brown, 2012;Heinrichs et al., 2007). The large diversification of this group probably occurred during the Triassic and Early Jurassic, perhaps coinciding with the recovery of landplant diversity from the PermianÀTriassic extinction (Anderson et al., 1999;Cooper et al., 2012;Heinrichs et al., 2007;Rees, 2002;Wing, 2004). A strong diversification seems to have occurred in the Cretaceous and early Palaeogene, which may coincide with the establishment of modern rainforests that were dominated by groups of angiosperms (Cooper et al., 2012;Heinrichs et al., 2007;Morley, 2000;Willis & McElwain, 2013). ...
Frullania Raddi is an extant genus of liverworts (Bryophytes) widespread around the world. It belongs to the family Frullaniaceae Lorch., with a large number of species distributed into several subgenera, sections and subsections according with different morphological classifications. As shown in previous studies, most Frullania sub-generic classifications are supported by molecular data, indicating that morphological characters appear well suitable to discriminate species. However, deep among-clade relationships remain unclear, probably due to the rapid diversification of main clades, paralleling other plant lineages. In this study, we reconstruct Frullania phylogeny based on available molecular data used in previous studies, and we present time estimates for the origin of its main branches. Results supported the monophyly of most subgenera as demonstrated in previous studies and supported a rapid diversification of these main lineages. Time estimates under a relaxed molecular clock and with integrated fossil evidence and nucleotide mutation rates further suggested a Jurassic origin of the genus and a rapid diversification during Palaeogene and Neogene. This may have been influenced by geographical and climate changes during these periods as predicted for most leafy liverworts.
... The glacial cycles began approximately 1.2 million years ago with a sequence of cold glacial ice ages and warm interglacial intervals (Pettit et al., 1999). During this time the average CO2 level of 200-280 ppm, maintained an average temperature of 9-21°C, which is suitable for sustaining recent life forms (Anderson et al., 1999). The radiation of mammals started during the cooling of the last hothouse in the Eocene epoch about 55 million years ago (Duplaix & Simon, 1976;Stucky & McKenna, 1993). ...
The world's climate follows a sequence of cold ice-age and warm sun-age periods, which affects its atmospheric CO2 levels and temperature (Kump, 2002). Artificial emissions of excessive carbon and greenhouse gasses by the modern developing world increased CO2 levels from the natural 280 ppm to 396 ppm by 2008, resulting in a rise in temperature of 2.2°C. A total meltdown of the Earth's ice-caps can be expected at >450-800 ppm, with a temperature rise of 4°C at the equator and 10-40°C at the poles. If the current trend of carbon emission continues, CO2 levels are likely to exceed 800 ppm by 2050. The anticipated global warming will change Africa's environments from grass dominated vegetation to dry woodland and karroid desert with an overall vegetation change from C3 to C4 dominated plants. As a result, animal species composition will need to adapt from predominantly grazer species to mixed feeders and browsers. Animal numbers will have to be decreased as the grazing capacity is expected to decline by more than 30%. Animals will also be more exposed to parasites and diseases. Adaptations in South Africa's wild animal species distributions are already evident. These factors will certainly impact on animal production. As part of the international initiative to combat the accumulation of artificial greenhouse gasses, animal feedlots emitting millions of tons of CH4, need to give way to more greenhouse friendly animal production systems. Globally, there is a general ignorance among wildlife and animal scientists regarding the effects of global climatic change on biodiversity and animal production.
... Glossopterid gymnosperms were overwhelmingly dominant through much of middle-to high-latitude Gondwana during the Permian (Anderson et al., 1999;McLoughlin, 2001) and were amongst the major casualties of the mass extinction event at the end of that period Vajda & McLoughlin, 2007). Thus far, all records of the glossopterid fructification Karingbalia are restricted to sedimentary basins within eastern Australia that formed along the convergent Panthalassan margin of southeastern Gondwana. ...
A new genus, Karingbalia is established to accommodate certain eastern Australian glossopterid fertile organs previously assigned to Ottokaria Zeiller emend. Pant et Nautiyal. Karingbalia differs from Ottokaria mainly by the sub-parallel rather than perpendicular orientation of basal peripheral lobes with respect to the receptacle margin. Moreover, Karingbalia ranges from the Artinskian to Changhsingian, whereas Ottokaria sensu stricto is probably confined to the Cisuralian. Two Karingbalia species are recognized: K. inglisensis McLoughlin comb. nov. from the Lopingian of the Bowen and Sydney basins; and K. nychumensis sp. nov. from Artinskian--lower Kungurian strata on the Georgetown Inlier. Several additional species of Ottokaria from across Gondwana do not conform precisely to the diagnosis of that genus and their taxonomic reappraisal is proposed.
... The overlying Madumabisa Formation palaeoflora is interpreted to represent a glossopterid woodland with an understorey of leptosporangiate and eusporangiate ferns, lycopods and sphenophytes with sparse peltasperms and conifers ( Table 2). The significant presence of various Protohaploxypinus and Striatopodocarpites species is consistent with the dominance of glossopterids across the Southern Hemisphere during the Permian (e.g., Anderson et al., 1999;Balme, 1995). Less common elements in the Gwembe and overlying Madumabisa formations include various monolete spores, and monosulcate and striate asaccate pollen (Table 2). ...
Increasing requirements for developing tools allowing fine strain traceability responsible for epidemics is tightly linked with the need to understand factors shaping pathogen populations and their environmental interactions. Bacterial wilt caused by the Ralstonia solanacearum species complex (RSSC) is one of the most important plant diseases (Mansfield et al., 2012) in tropical and sub-tropical regions. Sadly little or outdated, or no information on its epidemiology is reported in the literature, although alarming outbreaks are regularly reported as a disaster. A large set of phylotype I isolates (n = 2,608) was retrieved from diseased plants in fields across the South West Indian Ocean (SWIO) and Africa. This collection enabled further assessment of the epidemiological discriminating power of the previously published RS1-MLVA14 scheme. Thirteen markers were validated and characterized as not equally informative. Most had little infra-sequevar polymorphism and their performance depended on the sequevar. Strong correlation was found with a previously MLST scheme. However, 2-3% of sequevars were not correctly assigned through endoglucanase gene sequence. Discriminant Analysis of Principal Components (DAPC) revealed four groups with strong phylogenetic relatedness to sequevars 31, 33, and 18. Phylotype I-31 isolates were highly prevalent in the SWIO and Africa, but their dissemination pathways remain unclear. Tanzania and Mauritius showed the greatest diversity of RSSC strains, as the four DAPC groups were retrieved. Mauritius was the sole territory harboring a vast Phylogenetic diversity and all DAPC groups. More research is still needed to understand the high prevalence of phylotype I-31 at such a large geographic scale.
The narrow active temperature ranges of ectothermic tetrapods can be used as proxies for reconstructing paleoclimates. Here we deduce the climatic preferences of major Permo-Triassic tetrapod groups based on their known geographic distributions, the critical thermal limits of living tetrapods, and paleoclimate information from other sources. The resulting preferred temperature sequence of amniotes places most Triassic archosauromorphs at the high end of the spectrum, with preferred temperatures over 32 °C in some cases, followed by captorhinids, pareiasaurs, procolophonids, cynognathian cynodonts, dicynodonts (excluding Lystrosaurus), Proterosuchus fergusi, and finally Lystrosaurus at the lowest preferred temperature. The poleward distribution of Permian Lystrosaurus marks the border of cool temperate climates, whereas Triassic Lystrosaurus delineates the border of the arid zone. Most temnospondyls indicate the availability of perennial water sources. Captorhinids and pareiasaurs preferred dry climates, whereas dicynodonts preferred wetter conditions. Based on current evidence, central Pangea transitioned from an arid zone to a tropical zone during the late Olenekian.
The end-Permian crisis was the most severe extinction event in the Phanerozoic. In Southwestern Gondwana, this crisis was related to the development of the Choiyoi Silicic Large Igneous Province. In the Southern Hemisphere, the Glossopteridales were dominant in the Permian, and they declined at the Permian-Triassic boundary and were replaced by the Dicroidium flora. Argentinean Permian and Triassic floras are known for more than a century, but recently, new stratigraphic schemes and more accurate geochronological information have put in question the previous evolution models. Here we proposed a new scenario for the vegetation evolution during the Permian-Triassic boundary and early Middle Triassic in Argentina. During the Wuchiapingian-early Changhsingian interval, the floras were dominated by Glossopteridales, Cordaitales, Asterothecaceae, and Voltziales, and the oldest record of Umkomasiales (=Corystospermales), Peltaspermales, and Cycadales occurs. The Glossopteris flora would have disappeared in the Changhsingian before the end-Permian crisis. The late Changhsingian vegetation was dominated by cycads typical of the Dicroidium flora surviving in a refuge zone. After the end-Permian crisis, the recupera-tion was carried out by corystosperms, cycads and sphenophytes in the Induan-Olenekian interval. The Anisian plant communities were well-stabilised and diverse, corresponding to radiation of the Dicroidium flora. ARTICLE HISTORY
The Northern Atlantic Forest (NAF) covers a narrow strip along the Brazilian coast, from 3° to 19° S, over lowlands and plateaus. Mangroves, dunes, restingas, and forests occur from low to high altitudes, along an East-to-West climatic gradient. Initially covering 23 million hectares, NAF was reduced to 13%, much converted into sugarcane fields. Within NAF, in the North-eastern sugarcane zone (NESZ), land conversion happened in waves, the last in the middle 1970s, resulting in a predominant pattern of small-sized fragments in a sugarcane matrix. Acknowledged for its high endemism for plants, butterflies, and birds, high species numbers occur at a regional level and low numbers at the patch level, with a signal of taxonomic homogenization, simplification, and species loss; edge effects trigger retrogressive succession, while chronic disturbances like harvesting and hunting deplete plant and animal species. Despite all threats, some areas maintain high biodiversity and provide essential ecosystem services. Since most remnants are located within sugarcane properties, forest conservation relies on private-owned lands and their legal compliance to meet a vegetation debt that approaches 280,000 hectares and accomplish an ongoing initiative to restore approximately one million hectares. This is the key to a good prognosis for the NESZ Atlantic Forest.
Twelve mini chapters in Geologic Time Scale 2020 address Evolution and Biostratigraphy in key micro- and macrofossil groups. The chapters assist readers of the Geologic Period chapters to better understand and appreciate the role played by paleontology in describing and understanding Life on Earth in Deep Time.
Earth’s vegetation during the 186 million years of the Mesozoic, from the Paleogene–Cretaceous boundary at 66 million years ago back to the Triassic–Permian boundary at 252 million years ago, was filled with forests. Like today, the forest was the dominant terrestrial ecosystem. The trees that created the forest habitat, along with the other woody plants and ferns in the understory and groundcover, were the primary producers that powered Earth’s ecosystems by converting sunlight into chemical energy through photosynthesis. Yet, the forests that flourished during the Mesozoic differed from those found on Earth today. The Mesozoic climate was generally warmer, with milder seasons, a higher sea level, and no polar ice. This resulted in evergreen forests that may have looked superficially similar to gymnosperm-dominated forests of today, but were made up of very different kinds of plants. This is because major evolutionary changes took place in the plant world during this time interval. The Cretaceous witnessed the emergence and diversification of the flowering plants, which define our global flora now. In contrast, the Jurassic and Triassic floras were dominated by gymnosperms such as conifers and cycads, as well as by other, enigmatic, naked-seed plants including seed ferns and bennettitaleans that are now extinct. Continental drift tore landmasses apart, separating Northern Hemisphere floras with ginkgoes from the Gondwana flora in the south, which also is now extinct. Geological time, biotic evolution, and plate tectonics all contributed to the making of paleobotanically unique forests in different parts of the world. In this chapter, we present a series of written postcards from the Mesozoic, each one describing a forested landscape, as we travel back in time together on a virtual plant safari.
Phylogenetic relationships of Adenocarpus species were assessed by sequence analyses of the ITS and 3′ end of ETS (nrDNA) regions and the trnL–trnF intergenic spacer (cpDNA). The nrDNA analysis recovered four main clades within Adenocarpus. Clades 1–3 comprise morphological and molecularly well–differentiated species that occur in the western Mediterranean realm. Clade 4 comprises three distinctive endemic species from the Canary Islands, an endangered Algerian endemic, and a set of species close to A. complicatus with distinct geographical areas but with little molecular variation between taxa. The latter species are centred in the Iberian Peninsula but also distributed along the Mediterranean basin (from the Iberian Peninsula to Turkey). The phylogenetic position of A. mannii, a morphologically distinctive species with a unique afro–tropical distribution, is not unequivocally resolved, being sister to clade 3 in the ETS tree but to clade 4 in the ITS tree. Rates of evolution and ages of divergence of major groups were estimated using nonparametric rate smoothing with a fixed calibration point of 41.2 Ma and constraining the node of the separation of Anarthrophyllum and Mediterranean Genisteae at a minimum age of 13.6 and a maximum of 25.8 Ma. The estimated ages indicate that the diversification of Adenocarpus and first separation of two lineages may have occurred during the onset and the wake of the profound Middle Miocene cooling episode. One of the lineages separated rapidly into two groups (clades 1 and 2) while the second one led to clade 3, A. mannii and clade 4. Clades 1, 2 and 3 differentiated into the present species soon after these major events whereas clade 4 radiated much later, during the Pliocene.
The Carnian Aasvoëlberg 411 (Aas411) site of the Molteno Formation in South Africa provides exceptional data for understanding how plants, their arthropod herbivores and interactions responded to the P-Tr ecological crisis approximately 18 million years earlier. Our study lists six consequences stemming from the P-Tr event. First, Aas411 was one of the most herbivorized of Molteno’s 106 sites, consisting of 20,358 plant specimens represented by 111 plant form-taxa that includes 14 whole-plant taxa (WPT); the insect damage consists of 11 functional feeding groups (FFGs), 44 damage types (DTs) and 1127 herbivorized specimens for an herbivory value of 5.54%. Second, the seven most herbivorized hosts, in decreasing importance, were the conifer Heidiphyllum elongatum; corystosperm Dicroidium crassinervis; ginkgophyte Sphenobaiera schenckii, peltasperms Lepidopteris stormbergensis and L. africana and horsetail Zonulamites viridensis. Third, generalized feeding damage and 11 host-specialized associations were present that targeted 39 of 111 plant taxa. Fourth, the Heidiphyllum elongatum WPT was most herbivorized, harboring an extensive herbivore component community containing 81.8% of FFGs, 63.6% of DT categories, 40.9% of DT occurrences, and 36.4% of specialized interactions at the site. Fifth, eriophyioid gall DT70 was host-specialized on Dicroidium crassinervis, where it constitutes 70.1% of all Molteno DT70 occurrences and revealing a distinctive developmental ontogeny. Sixth, herbivory levels significantly surpassed those of the Late Permian.
The Triassic was a time of diversification of the global floras following the mass-extinction event at the close of the Permian, with floras of low-diversity and somewhat uniform aspect in the Early Triassic developing into complex vegetation by the Late Triassic. The Earth experienced generally hothouse conditions with low equator-to-pole temperature gradients through the Late Triassic. This was also the time of peak amalgamation of the continents to form Pangea. Consequently, many plant families and genera were widely distributed in the Late Triassic. Nevertheless, two major floristic provinces are recognizable during this interval—one in the Southern Hemisphere (Gondwana) and another in the Northern Hemisphere (Laurussia); these being largely separated by the Tethys Ocean and a palaeotropical arid belt. Regional variations in topography, climate and light regime imposed further constraints on the distribution of plant groups in the Late Triassic such that two floristic sub-provinces are recognizable within Gondwana, and nine within Laurussia based on the plant macrofossil and dispersed spore-pollen records. In a broad sense, the Late Triassic saw the diversification of several plant groups that would become important components of younger Mesozoic floras (e.g., Bennettitales, Czekanowskiales, Gnetales and several modern fern and conifer families). The representation of these groups varied not only geographically, but waxed and waned through time in response to climatic pulses, such as the Carnian Pluvial Event. Significant turnovers are apparent in both macrofossil- and palyno-floras across the Triassic–Jurassic boundary, especially in the North Atlantic and Gondwanan regions. The geographic and temporal variations in the floras have necessitated the establishment of numerous regional palynozonation schemes that are tentatively correlated in this study. Major plant macrofossil assemblages of the Late Triassic world are also placed in a stratigraphic context for the first time. The Late Triassic floras also record the re-diversification of insect faunas based on a broad array of damage types preserved on leaves and wood. By the Late Triassic, all modern terrestrial arthropod functional feeding groups were established, and several very specialized feeding traits and egg-laying strategies had developed. Although age constraints on various fossil assemblages need to be improved, this study provides the first global overview of the temporal and geographic distributions of Late Triassic floras, and establishes a basis for future targeted research on Triassic phytogeography and phytostratigraphy.
Carbon isotopes are being used increasingly for high resolution chemostratigraphy. δ13C variations provide relative temperature scales that can be complemented with litho- and bio-stratigraphy to reconstruct local ecosystem and global climate shifts. We present the first Karoo terrestrial organic carbon isotope curve, calibrated against U/Pb zircon dates from interbedded ash-fall tuffs, which can be used for correlation between separate terrestrial Gondwana basins and with marine sequences elsewhere. We identify a number of distinct shifts in the carbon isotope stratigraphy of the Karoo and explore these to discuss punctuated and gradational changes linked to local paleoenvironments and global climates, from polar to desert conditions, over a span of about 200 million years that includes two major extinction events.
An ice age in Famennian (Late Devonian) time is documented by the presence of diamictites with striated, faceted and polished pebbles; rhythmites with dropstones; erratic boulders; and striated pavements and deformed sandstones. The glacigenic beds occur in three huge intracratonic basins (Solimões, Amazonas and Parnaíba) and in one pericratonic basin (Acre) in northern Brazil. Other possible Late Devonian diamictites may occur elsewhere in Brazil and Africa which, if confirmed, would extend considerably the area affected by this glacial age.
The onset of the Late Devonian glaciation caused a global narrowing of the warm climatic belts, sharp regression, increased clastic sedimentation, massive biotic extinction, reduced biochemical deposition and unconformities. This resulted in important facies changes in the world geological record.
Ice centers moved from northern Africa to southwestern South America from Late Ordovician to Early Silurian time. From Mid-Silurian to early Late Devonian time no record of glaciation is known. In late Late Devonian time intermittent glaciation began again in central South America and, from late Late Devonian to early Late Permian time, ice centers migrated towards Antarctica across South America and South Africa.
The Devonian and Ordovician—Silurian glaciations together with the better known Permo-Carboniferous glaciations may all have primarily resulted from the shifting posi¬tion of the Gondwana continent with respect to the South Pole.
Under the name of Sahnia nipaniensis gen. et sp. nov. the author describes some specimens which he believes to be the male flowers of the Pentoxyleae. These were borne apically on dwarf shoots closely resembling those of Pentoxylon Sahnii Srivastava. The flower consists of filiform spirally branched microsporophylls, fused proximally to form a disc which surrounds a broad and conical receptacle. The unilocular sporangia are borne at the ends of short branches of the sporophylls. Pollen grains are monocolpate and boat-shaped. In young flower the microsporophylls are surrounded by a whorl of deciduous bracts. The infructescence of Carnoconites laxum and several specimens (showing longitudinal section) of the infructescence of C. compactum have also been discovered. The infructescence of C. laxum differs from that of C. compactum in having much shorter pedicels and much longer female cones. The infructescence of C. compactum differs from the reconstruction made by Professor Sahni in the absence of bifurcation of the pedicels and in the arrangement of the cones.
Fossil wood was collected from sediments on the Namaqualand shelf, between the Orange River mouth and just to the south of Kleinzee. Forty three of these samples are described. All the woods are gymnospermous and have abietinian tracheid pitting. Nineteen of them are well enough preserved to be identified to species level: Podocarpoxylon cf. umzambense, Mesembrioxylon cf. stokesii, M. cf. sahnii, M. cf. woburnense and Protocupressinoxylon cf. purbeckensis. The woods are probably primitive members of the Podocarpaceae growing during the Lower Cretaceous. They indicate a seasonal climate and inhabited the extensive low-lying coastal regions. -from Authors
A middle Cretaceous (Cenomanian) fossil flora from the Winton Formation of central Queensland consists of six taxa of ferns, four conifers, one ginkgophyte, one pentoxylalean, and eight angiosperm leaf types. It is the oldest impression flora to contain abundant angiosperm leaves to date described in detail from Australia, and provides the first, direct, macrofossil evidence of the transition from gymnosperm- to angiosperm-dominated floras in Australia during the Cretaceous. The angiosperm leaves are mostly hamamelid types of probable fagaceous or betulaceous affinity, but precise relationships are unclear. The Winton angiosperm assemblages show some similarity to Late Cretaceous floras of New Zealand. -Authors
The Karoo Basin extends over more than half of the South African land surface and incorporates sediments deposited over a period of more than 100 million years, from the Upper Carboniferous to the Lower Jurassic. Biozones have been established on the basis of the abundant vertebrate fauna. Fossil plant deposits are numerous but best represented by the Lower Permian Glossopteris floras and Middle to Upper Triassic Dicroidium floras. Fossil woods occur throughout the sequence. In this paper previously described woods are discussed, newly collected woods are described and an attempt is made to correlate the woods with the Formations and vertebrate biozones. Prototaxoxylon africanum (Walton) Krausel and Dolianiti is common but restricted to the Permian (Ecca and Lower Beaufort Groups). Prototaxoxylon uniseriale Prasad has the same distribution but is rare. Australoxylon teixeirae Marguerier extends from the Ecca to the middle Beaufort. Araucarioxylon occurs throughout the Karoo but there are several species that have different ranges. Araucarioxylon africanum Bamford sp. nov. occurs throughout the Beaufort and into younger deposits. Araucarioxylon karooensis Bamford sp. nov. occurs in the Normandien Formation of the Beaufort Group. Woods with podocarpacean affinities, recognized as Mesembrioxylon, first occur in the uppermost Beaufort and extend into the Cretaceous. The woods can, therefore, be used as broadscale biostratigraphic indicators but further data need to be collected.
During the last three decades, there has been a steady flow of papers on the paleobotany and stratigraphy of India and Antarctica. This chapter will consider the various megafossil assemblages from these regions, which range in age from Lower Permian to Lower Cretaceous. Previously, the oldest rocks in the Gondwana Sequence of India were thought to be Late Carboniferous, but these are now believed to represent the Lower Permian. Although the sequence of formations within the Permian is fairly well established (Table 10.2), the ages and sequential positions of the various younger formations [above the Panchet Formation (lowermost Triassic), Table 10.1] are still debated. In some cases, the Jurassic-Lower Cretaceous formations rest directly on metamorphic rocks or gneisses believed to be of Archaean origin. Nowhere have these formations been observed superimposed in sequential order.
É descrito novo inseto da família Diaphanopteridae: Philiasptilon huenickeni Pinto et Ornellas, sp. nov., da Formação Bajo de Veliz, Provincia de San Luis, Argentina. É discutida a idade, concluindo os autores pelo Carbonífero Superior para os sedimentos contendo insetos.
Antarctic Paleobiology discusses the current status of paleobiology, principally paleobotany and palynology in Antarctica, and the interrelationship of Antarctic floras to those of other Gondwana continents. It provides a broad coverage of the major groups of plants on the one hand, while on the other seeking to evaluate the vegetational history and the physical and biological parameters that influence the distribution of floras through time and space. The biologic activity is discussed within a framework of the geologic history, including the tectonic and paleogeographic history of the region. Finally, the reader will find a comprehensive bibliography of Gondwana paleobotany and palynology.
Through a comprehensive analytical study of the Mesozoic flora and synthesis of the available data 12 assemblage zones and a floral succession are established. These assemblage zones also extend into the Early Cretaceous flora in the neighboring countries: Pakistan, Nepal, Bhutan and Sri Lanka. The Gondwana Triassic elements and the European Jurassic-Cretaceous elements in the flora are highlighted. The inter-relationship of the Mesozoic floras of Gondwanaland, European and Asian countries is examined. The relative age of the biozones is worked out on the basis of plant megafossils, palynology, paleontology, stratigraphy and radiometry. It is suggested that the concept of Gondwana be replaced by chronostratigraphic terms, viz., Triassic, Jurassic and Cretaceous for the Indian Mesozoic sediments.
The Permian and Triassic floras of Gondwana are known almost exclusively from impression/compression specimens. Generally, Permian floras from the southern hemisphere demonstrate a low diversity and are often poorly preserved as impressions. By comparison, floras of Triassic age display much greater diversity and are often better preserved, some with cuticular remains.The reconstruction of reproductive organs in this group is based almost completely on impression remains. Dictyopteridium has been interpreted by some as representing a three-dimensional cone bearing helically arranged ovules (Surange and Chandra 1975; Rigby 1978); others believe it should more accurately be depicted as a flattened, somewhat fleshy structure with bilateral symmetry (e.g.,Pant 1987).
The origin of the angiosperm flower may be interpreted as the result of a co-evolutionary relationship between insects and as yet unknown angiosperm ancestors. This chapter discusses the course of the relationship between the pollinating insects and the flowering plants and its possible significance in angiosperm success and diversification patterns. A tentative chronology is proposed. -P.J.Jarvis
The study is concerned with the floristics and evolutionary trends of the South African megaplants over the 300 Ma span from the Devonian to the Lower Cretaceous: from the appearance of the first vascular land plants to the appearance of the first flowering plants. The information recorded incorporates the result of much new collecting and a comprehensive standardised taxonomic revision of all the fossil plant material available in South Africa. The history of 140 yr of fossil plant collecting is reviewed and brief biographies of 35 fossil-plant collectors are given, who made contributions to South African palaeobotany. 91 genera and 263 species are dealt with, of which 11 genera and 67 species are described as new; 20 new combinations of name are proposed. All floras are comprehensively illustrated with figures, plates, charts and maps. Eighteen successive megafloras are recognised. These are listed with concise data on their lithostratigraphy, palaeoenvironment, collections, preservation, associations, accompanying faunas and their age. It is concluded that South Africa must be taken to represent Africa south of the Sahara for this period, because of the lack of described floras elsewhere in the continent (the Permian excepted). In South Africa the Permian and the Triassic deposits are the most productive, the Devonian and the Lower Cretaceous intermediate and the Carboniferous and Jurassic barren or nearly so. Maximum species numbers are recorded in the Upper Triassic Molteno Formation 8115 species) and the plant diversity curve reflects the three major global lithospheric/atmospheric crises recorded during this period. The voids in the Carboniferous and the Jurassic coincide with extensive glaciations and vulcanicity respectively, while the Permian decline follows a global desiccation event. Whereas the diversity curve for the Gondwana Realm follows that for South Africa in general, the Euramerican curve shows fundamental differences. The Carboniferous and Jurassic hiatuses in Gondwanaland were contemporaneous with periods of flourishing growth and diversity in Euramerica.-from Authors
São descritos novos insetos carboníferos da Bacia do Paraná, Brasil, pertencentes a novas famílias da: Ordem Protorthoptera; Proedischiidae fam. nov. com uma espécie Proedischia mezzalirai gen. et sp. nov.; e da Ordem Paraplecoptera, Narkemocacurgidae fam. nov. com as espécies Narkemina rodendorfi, sp. nov.; N. rochacamposi, sp. nov. e mais quatro espécies indeterminadas de Narkemina, sendo uma da África (Madagascar). É discutida a idade do Subgrupo Itararé e apresentados alguns dados para a correlação e paleogeografia do Gondwana.
Fitting the generalized inverse Gaussian-Poisson distribution (GIGP) to observed frequency distributions of taxa from the Late Triassic Molteno Formation of South Africa has yielded estimates of the corresponding preserved biodiversities. Three extrapolations have been made on the basis of the uniquely rich megaflora/insect coassemblages from 100 taphocoenoses: insect species - 335 observed, 7740 preserved; vegetative species - 206 observed, 667 preserved; gymnosperm ovulate orders - 16 observed, 84 preserved. The reliability of the results varies according to the abundance and observed diversity of the taxa. These results, with further estimations in a companion paper of existed diversity (regional, continental and global), hint at Late Triassic floral and faunal richness akin to today. This conflicts with the traditionally held model of an increasing cone of biodiversity through time and suggests a phase of explosive evolution in the Triassic hitherto unsuspected. Application of the GIGP to other well-documented collections from other periods might reveal a pattern of diversity trends offering fundamentally new insights into the evolving terrestrial biosphere.
The first descriptions of the fossil plants included in the so-called 'Juan de Morales Flora', from the classic locality Quebrada Juan de Morales, ca. 75 km east of Iquique, Tarapacá Region, Chile, are given. The flora is composed of Neocalamites sp., Dictyophyllum sp., Gleichenites sp., Zamites antarcticus Halle, Zamites cf. pusillus Halle, Zamites sp., Anomozamites sp., Brachyphyllum sp. and an incertae sedis seed. Stratigraphically, the flora is located in the upper section of the Chacarilla Formation, composed mainly of red sandstones and siltites of continental origin. The generally accepted Jurassic age of the flora is confirmed, and herein restricted to the Middle Jurassic.
By tradition the first land plants originated in the North Atlantic Region—particularly in Britain (Boucot and Gray 1982).
4 Permo-Triassic correlation charts are presented: one on Laurasia and 3 on Gondwana (W, E, and Circum-Gondwana). Current biostratigraphic data on 4 groups of organisms - marine invertebrates, palynomorphs, megaplants, tetrapods - form the basis of the correlations. Each chart includes from 15 to 20 columns depicting the most productive comprehensive sections in the region. An account of marine and terrestrial realms and provinces accompanies the charts. -Author
A first attempt is made to integrate the plant, insect and tetrapod elements of the Late Triassic (Carnian) intracontinental, braidplain ecosystems of the Karoo Basin, South Africa. These are probably the richest known for this pivotal early Mesozoic interval when the dinosaurs, mammals, some insect orders and possibly the birds and flowering plants made their earliest appearance. Intensive sampling of 100 Molteno Formation taphocoenoses has yielded 56 genera with 206 species of plant (vegetative taxa) and 117 genera with 335 species of insect. Seven major habitats are identified and described, ranging from two types of riparian forest through open woodland to coniferous thicket, horsetail marsh and fern meadow. Each shows a distinctive plant/insect co-association. The tetrapod-vertebrate component of these associations is based on the Lower Elliot Formation, the assumed distal facies and time equivalent of the upper four members of the Molteno Formation. This is a sparse (seven taxa) early dinosaur fauna including both body fossils and trackways. The Upper Elliot Formation has a richer tetrapod fauna and may, in future, be used to model possible missing elements of the Lower Elliot Formation. Comparison of the Molteno insect fauna with that of two other Carnian deposits, in Australia (Ipswich Basin) and North America (Newark Basin), reveals marked provinciality reflecting temperate and tropical latitudes.
Um plano lenhoso, com estrutura primária preservada, referente a Lebachiaceae, é registrado nas camadas do Gondwana sul-brasileiro (Formação Irati, RS); Scleromedulloxylon batoviense GUERRA 1976 é aqui descrito. Problemas nomenclaturais referentes a Tylodendron (WEISS) FLORIN 1940, são também discutidos.
Land plants have evolved in the selective context of their surrounding environment. Climate has long been discussed as a selective force, but the effects of vertebrate herbivores may also be significant. Four phases of vertebrate herbivory may be recognized in the fossil record. The Silurian-Late Carboniferous apparently lacks vertebrate herbivores. The Early Permian-Late Triassic is dominated by low-feeding therapsids. The Late Triassic-K/T boundary is dominated by large archosaurian herbivores. The Tertiary-Present is dominated by small birds and mammals. Recognition of these changing forces of vertebrate herbivory will aid in understanding the evolution of vascular plants.
Plant fossils from Antarctica have played a major role in developing concepts of the geological history of the Southern Hemisphere. Disjunct austral distributions of extant taxa (e.g., Hooker 1853) and the strong floristic similarities between the Permo-Triassic Glossopteris floras on the austral land masses (e.g., Halle 1937) were important in establishing that now separate continental areas were once contiguous. Since widespread acceptance of continental drift, paleobotanical contributions to ideas of continental realignment have emphasized the delimitation of floristic provinces (“phytochoria” sensu Meyen 1987) and assessments of overall similarities among fossil floras from different areas (e.g., Chaloner and Meyen 1973, Chaloner and Lacey 1973, Vakhrameev et al. 1978, Chaloner and Creber 1988). An alternative approach, made possible by recent developments in systematics, uses patterns of phylogenetic relationship in different taxa to develop and test hypotheses about relationships between different areas and patterns of geographical fragmentation (Brundin 1966, Rosen 1978, Nelson and Platnick 1981, Nelson and Rosen 1981, Platnick and Nelson 1978, Humphries and Parenti 1986).
Far from being globally warm throughout the 78 m.y. of the Cretaceous, this was a time of quite variable climates. At the beginning of the Cretaceous, climates were changing from an episode of global aridity at the end of the Jurassic to much more humid environments through the Cretaceous. There are no records of ice-rafted deposits from the late Albian onwards, indicating that high-latitude climates became much warmer. However, the interval from the Cenomanian to the Santonian appears to have been a time of quite variable climates. During the final part of the Cretaceous there was a distinct cooling trend. Both ocean and land temperatures dropped considerably. The latest part of the Maastrichtian appears to have been especially cool, with low temperatures, even freezing, at high latitudes and conditions perhaps similar to those of the early Cretaceous. All climate evidence points to a warming again during the Palaeocene. -from Authors