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An Extinct Fruit Species of Fabaceae from the Early Eocene of Northwestern Wyoming, USA
... Legumes also have an abundant and diverse fossil record, with numerous fossil flowers, fruits, and leaves documented from the Cenozoic of every continent except Antarctica (Herendeen, 1992;. Temporal and biogeographic patterns in the fossil record of the family were summarized by , to which have been added more recent fossil reports from low paleolatitude localities, mainly in Africa and Central and South America (Herendeen and Jacobs, 2000;De Franceschi and De Ploëg, 2003;Jacobs and Herendeen, 2004;Calvillo-Canadell and Cevallos-Ferriz, 2005;Brea et al., 2008;Wing et al., 2009;Pan et al., 2010Pan et al., , 2012Collinson et al., 2012;Cantrill et al., 2013;Jia and Manchester, 2014;Shukla and Mehrotra, 2016;Herendeen and Herrera, 2019;Herrera et al., 2019;Lyson et al., 2019;Shukla et al., 2019;Jia et al., 2021;Li et al., 2021). By the middle Eocene all major lineages within the family are documented in the fossil record, and many securely identified fossils have been used to calibrate branch ages from molecular phylogenetic analyses Lavin et al., 2005;Bruneau et al., 2008;Magallon et al., 2015;Estrella et al., 2017;Koenen et al., 2021). ...
Premise:
Understanding the evolutionary history of flowering plants has been enriched by the integration of molecular phylogenies and evidence from the fossil record. Fossil fruits and leaves from the late Paleocene and Eocene of Wyoming and Eocene of Kentucky and Tennessee are described as extinct genera in the tropical American Bowdichia clade of the legume subfamily Papilionoideae. Recent phylogenetic study and taxonomic revision of the Bowdichia clade have facilitated understanding of relationships of the fossil taxa and their evolutionary implications and paleoenvironmental significance.
Methods:
The fossils were studied using standard methods of specimen preparation and light microscopy and compared to fruits and leaves from extant legume taxa using herbarium collections. Phylogenetic relationships of the fossil taxa were assessed using morphology and DNA sequence data.
Results:
Two new fossil genera are described and their phylogenetic relationships are established. Paleobowdichia lamarensis is placed as sister to the extant genus Bowdichia and Tobya claibornensis is placed with the extant genera Guianodendron and Staminodianthus.
Conclusions:
These fossils demonstrate that the tropical American Bowdichia clade was present in North America during a period when tropical or subtropical conditions prevailed in the northern Rocky Mountains during the late Paleocene and the Mississippi Embayment during the middle Eocene. These fossils also document that the Bowdichia clade had diversified by the late Paleocene when the fossil record of the family is relatively sparse. This result suggests that future work on early fossil legumes should focus on tropical and subtropical climatic zones, wherever they may occur latitudinally.
The birth of modern rainforests
The origin of modern rainforests can be traced to the aftermath of the bolide impact at the end of the Cretaceous. Carvalho et al. used fossilized pollen and leaves to characterize the changes that took place in northern South American forests at this time (see the Perspective by Jacobs and Currano). They not only found changes in species composition but were also able to infer changes in forest structure. Extinctions were widespread, especially among gymnosperms. Angiosperm taxa came to dominate the forests over the 6 million years of recovery, when the flora began to resemble that of modern lowland neotropical forest. The leaf data also imply that the forest canopy evolved from relatively open to closed and layered, leading to increased vertical stratification and a greater diversity of plant growth forms.
Science , this issue p. 63 ; see also p. 28
Based on examination of 352 specimens collected from the Puryear clay pit (middle Eocene Cockfield Formation, Claiborne Group), Henry County, Tennessee, we recognize 72 fossil taxa/morphotypes of angiosperms. Thirty-two taxa/morphotypes are related to the following 12 extant families: Altingiaceae (2), Araliaceae (1), Arecaceae (2), Cannabaceae (1), Ceratophyllaceae (1), Euphorbiaceae (1), Fabaceae (11), Fagaceae (7), Juglandaceae (3), Oleaceae (1), Theaceae (1), and Ulmaceae (1). The rest (40 taxa/morphotypes) do not have enough diagnostic characters to assess their modern affinities. We establish two new fossil species Andrewsiocarpon puryearensis sp. nov. (Theaceae) and Paleopanax puryearensis sp. nov. (Araliaceae). Of the 72 taxa/morphotypes recognized, 50 are unique to the Puryear locality (Cockfield Formation), 11 are shared with the Warman locality (Cockfield Formation), eight are shared with the Bovay and Bolden localities (Tallahatta Formation), and three are shared by all three localities. Of the 155 taxa/morphotypes recognized from the Bovay/Bolden, Warman, and Puryear localities, only three taxa/morphotypes are shared by all three localities. This study has expanded our knowledge of the Eocene plant diversity of the southeastern United States and has further confirmed our previous observation that there is a remarkable lack of species overlap among the localities examined to date.
The climatic impacts of the Tibetan Plateau since the Neogene and the phytogeographic pattern changes of formerly widely‐distributed forest communities on the plateau remain poorly constrained. Today, Cercis L. (Fabaceae) is a well‐known arborescent genus typically distributed in subtropical to warm temperate zones of the Northern Hemisphere, and Paleogene fossil occurrences from Eurasia and North America show a long history of the genus in mid‐low latitudes of the Northern Hemisphere. Here, we describe a fossil species, Cercis zekuensis sp. nov. based on well‐preserved fruits from the early Miocene of the northeastern Tibetan Plateau. Detailed morphological comparison (e.g. ventral margin with a veinless wing) of extant and fossil members of Cercis and other genera confirmed validity of the present taxonomic identity. Based on the comparison with extant relatives and their climate preferences, this unexpected occurrence of thermophilic Cercis in northeastern Tibetan Plateau indicates this area had higher temperature and precipitation in the Miocene than today. Integrated with inferred (paleo‐)temperature lapse rates, this indicates a low paleoelevation of less than 2.4 km. In contrast with the present‐day alpine climate here (~3.7 km), such a low elevation facilitated a more favorable habitat with comparatively high biodiversity and warm temperate forests at that time, as were evidenced by co‐occurring megafossils. Moreover, the present existence of Cercis implies the genus was widespread in interior Asia during the early Neogene and shows its modern disjunction or diversification between eastern and central Asia was possibly shaped by the late Cenozoic regional tectonic uplift and consequential environmental deterioration.
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The middle Eocene (Lutetian) fossil plant assemblage from Tatabánya (N Hungary) comprises plant remains preserved mostly as impressions. Remains of angiosperms are represented by Lauraceae (Laurophyllum div. sp., Daphnogene Unger), Rhamnaceae (Ziziphus Miller), Malvaceae s.l. (Byttneriopsis Z.Kvaček et Wilde), Leguminosae, and Palmae, and the occurrence of other families, i.e., Dioscoreaceae, Myrtaceae, Fagaceae, Anacardiaceae, Berberidaceae, Juglandaceae, and Theaceae, is uncertain. The scarcity of gymnosperms is a character similar to the coeval floras of Csordakút (N Hungary) and Girbou in Romania. The presence of Ziziphus ziziphoides (Unger) Weyland, high number of linear shaped leaves with entire margin and coriaceous texture (Lauraceae vel Fagaceae), and small-leaved Leguminosae suggests a “subhumid” character of the vegetation, which is recognisable also in early Palaeogene floras of eastern Central and Southeastern Europe, e.g., the Tard Clay floras in Hungary and floras of Serbia/Macedonia. In contrast, the Eocene floras from Central/Western Europe are indicative of a generally non-xerophytic character, e.g., Staré Sedlo in Bohemia, Messel, Geiseltal, and the Weisselster Basin floras in Germany. A frost-free climate with high mean annual temperatures similar to that estimated for coeval European floras may also be inferred for the Tatabánya flora.
Terrestrial record of recovery
The extinction that occurred at the end of the Cretaceous period is best known as the end of the nonavian dinosaurs. In theory, this paved the way for the expansion of mammals as well as other taxa, including plants. However, there are very few direct records of loss and recovery of biotic diversity across this event. Lyson et al. describe a new record from the Cretaceous-Paleogene in Colorado that includes unusually complete vertebrate and plant fossils that describe this event in detail, including the recovery and expansion of mammalian body size and increasing plant and animal biotic diversity within the first million years.
Science , this issue p. 977
Leguminosae are one of the most diverse flowering-plant groups today, but the evolutionary history of
the family remains obscure because of the scarce early fossil record, particularly from lowland tropics. Here, we report
~500 compression or impression specimens with distinctive legume features collected from the Cerrejón and Bogotá
Formations, Middle to Late Paleocene of Colombia. The specimens were segregated into eight fruit and six leaf
morphotypes. Two bipinnate leaf morphotypes are confidently placed in the Caesalpinioideae and are the earliest
record of this subfamily. Two of the fruit morphotypes are placed in the Detarioideae and Dialioideae. All other fruit
and leaf morphotypes show similarities with more than one subfamily or their affinities remain uncertain. The abundant
fossil fruits and leaves described here show that Leguminosae was the most important component of the earliest rainforests
in northern South America c. 60–58 million years ago.
Premise of research. Fossil leaves from the early Eocene Green River Formation of Wyoming and late Eocene Florissant Formation of Colorado have been studied and described here as two species in the monospecific extant genus Arcoa (Leguminosae, subfamily Caesalpinioideae). The single living species of Arcoa is endemic to the Caribbean island of Hispaniola. The species from Florissant has been known since the late 1800s but has been incorrectly treated as several different legume genera. Methodology. The compression fossils were studied using standard methods of specimen preparation and microscopy. Fossils were compared with extant taxa using herbarium collections at the Field Museum and Smithsonian Institution. Pivotal results. The fossil bipinnate leaves exhibit an unusual morphological feature of the primary rachis, which terminates in a triad of pinnae, one terminal flanked by two lateral pinnae, all of which arise from the same point at the apex of the rachis. This feature, combined with other features that are diagnostic of the family Leguminosae or subgroups within it, allows the taxonomic affinities of the fossil leaves to be definitively determined as representing the extant genus Arcoa, which is restricted to the Caribbean island of Hispaniola today. Conclusions. The fossil leaves described in this article demonstrate that the monospecific genus Arcoa was more diverse and had a much more widespread distribution in the past than it has today. Although the two fossil species are clearly referable to the same genus, differences between them in leaf size are consistent with differences in climate that are inferred for the more tropical Fossil Lake flora of the Early Eocene Green River Formation as compared with the warm temperate Late Eocene Florissant flora.
Premise of research. Species richness of Leguminosae (Fabaceae) is highest in the Neotropics today, but the fossil evidence of the family from this region remains sparse. The study of a fossilized indehiscent winged fruit (samara) from a recently discovered flora from the late Eocene Esmeraldas Formation in Colombia increases our understanding of the fossil record of Leguminosae from the Neotropics and sheds light on the evolution and ecology of this emblematic angiosperm family. Methodology. Plant fossils were collected from a new locality in the late Eocene Esmeraldas Formation. Fifteen fossilized samara fruits were described and compared to fossil and extant angiosperm fruits based on herbarium collections and literature. Taxonomic affinities of the fossil fruits within the clade Dalbergieae (Papilionoideae, Fabaceae) were evaluated by a combined analysis of morphological and molecular data. Pivotal results. A new fossil fruit, Luckowcarpa gunnii gen. and sp. nov., is described and associated with the Pterocarpus clade (Dalbergieae) based on the presence of two-seeded unicarpellate samaras with a proximal seed chamber and a style remnant at the distal end of the wing. Luckowcarpa gunnii represents the earliest fruit fossil record of the Dalbergieae clade. Conclusions. The phylogenetic position of L. gunnii, nested within the clade Dalbergieae, supports the hypothesis that legume diversification occurred early in the Tertiary in low latitudes and suggests that this fossil taxon could have been adapted to tropical dry forest ecosystems.
The classification of the legume family proposed here addresses the long-known non-monophyly of the traditionally recognised subfamily Caesalpinioideae, by recognising six robustly supported monophyletic subfamilies. This new classification uses as its framework the most comprehensive phylogenetic analyses of legumes to date, based on plastid matK gene sequences, and including near-complete sampling of genera (698 of the currently recognised 765 genera) and ca. 20% (3696) of known species. The matK gene region has been the most widely sequenced across the legumes, and in most legume lineages, this gene region is sufficiently variable to yield well-supported clades. This analysis resolves the same major clades as in other phylogenies of whole plastid and nuclear gene sets (with much sparser taxon sampling). Our analysis improves upon previous studies that have used large phylogenies of the Leguminosae for addressing evolutionary questions, because it maximises generic sampling and provides a phylogenetic tree that is based on a fully curated set of sequences that are vouchered and taxonomically validated. The phylogenetic trees obtained and the underlying data are available to browse and download, facilitating subsequent analyses that require evolutionary trees. Here we propose a new community-endorsed classification of the family that reflects the phylogenetic structure that is consistently resolved and recognises six subfamilies in Leguminosae: a recircumscribed Caesalpinioideae DC., Cercidoideae Legume Phylogeny Working Group (stat. nov.), Detarioideae Burmeist., Dialioideae Legume Phylogeny Working Group (stat. nov.), Duparquetioideae Legume Phylogeny Working Group (stat. nov.), and Papilionoideae DC. The traditionally recognised subfamily Mimosoideae is a distinct clade nested within the recircumscribed Caesalpinioideae and is referred to informally as the mimosoid clade pending a forthcoming formal tribal and/or cladebased classification of the new Caesalpinioideae. We provide a key for subfamily identification, descriptions with diagnostic charactertistics for the subfamilies, figures illustrating their floral and fruit diversity, and lists of genera by subfamily. This new classification of Leguminosae represents a consensus view of the international legume systematics community; it invokes both compromise and practicality of use.
The presenr Bora of southeasreen Unired Srares IS che producr of a long h)5rory of plane migrations and lneermln gling ofvarious caxa from remper"e, warm
In this report, we examine fossil plant reproductive materials from the Warman clay pit in western Tennessee. The investigation of about 600 specimens has resulted in the recognition of 60 species and morphotypes. Based upon comparisons of gross morphology of these specimens with available extant plant materials and the literature, we have been able to assess their affinities with 16 extant families. We are able to relate 36 species and morphotypes to the following families: Altingiaceae, Annonaceae, Araceae, Araliaceae, Bignoniaceae, Euphorbiaceae, Fabaceae, Fagaceae, Hamamelidaceae, Juglandaceae, Lauraceae, Magnoliaceae, Malpighiaceae, Moraceae, Oleaceae, and Theaceae. In addition, 24 morphotypes are not assigned to any family due to the limited number of diagnostic characters. This report represents a comprehensive review on the reproductive materials from a single locality of the Claiborne Group of the southeastern United States. Compared to traditional investigations focused primarily on leaves, this study provides a different perspective for understanding plant diversity for the middle Eocene Claiborne Group.
Podocarpium A. Braun ex Stizenberger is one of the most common legumes in the Neogene of Eurasia, including fossil fruits, seeds, leaves, and possible flower and pollen grains. This genus is not completely consistent with any extant genera according to gross morphological characters and poorly preserved cuticular structures reported in previous studies. The fossil pods collected from the coal-bearing series of the Changchang Basin of Hainan Island and Maoming Basin of Guangdong, South China, are examined by morphologically comparative work, with special reference to venation patterns and placental position. These distinctive features, as well as the ovule development of pods from different developmental stages and the epidermal structure of the pods, as distinguished from previous records lead to the conclusion that these fossils can be recognized as a new species of Podocarpium, P. eocenicum sp. nov. This new discovery indicates that Podocarpium had arrived in South China by the Eocene. Investigation on the fossil records of this extinct genus shows that P. eocenicum is the earliest and lowest latitude fossil data. The possible occurrence pattern of this genus is revealed as follows: Podocarpium had distributed in the South China at least in the middle Eocene, and then migrated to Europe during the Oligocene; in the Miocene this genus reached its peak in Eurasia, spreading extensively across subtropical areas to warm temperate areas; finally, Podocarpium shrank rapidly and became extinct in Eurasia during the Pliocene.
The fossil flora of Huadian, Jilin Province, China, is described based on leaves fruits, and one calyx. The megafossil plant remains occur in siltstones associated with oil shales that yield the Middle Eocene mammalian fauna. We provide a floristic inventory as a basis for comparison with floras of corresponding age in North America and Europe. Leaves of Ginkgo, Metasequoia, Trochodendroides, Platanus, Castanea, Quercus, Carya, and numerous undetermined dicotyledonous taxa, along with fruits of Menispermaceae (two genera), Rhus, Koelreuteria, and Craigia, and also calyx of Chaneya are included. The occurrence of Menispermaceae on the basis of fruits is a new record for the Eocene of Asia. The new combination, Zizyphoides ezoensis (Tanai) is presented for leaves of apparent trochodendraceous affinity. The Huadian flora also provides the first unequivocal fruits of Koelreuteria (Sapindaceae) from the Eocene of China. The taxonomic composition of the flora is consistent with an interpretation of temperate climate. The Huadian flora shares up to 37% of its megafossil genera with Middle Eocene floras of western North America, but only about 16% of its genera with Middle Eocene floras of Germany. These differences may reflect similar climate and land continuity between western North America and eastern Asia, as well as Eocene climatic differences and intervening barrier between eastern Asia and central Europe.
A survey of the extensive fruit and seed collections from the Middle Eocene oil shale of the Messel
Formation, at Messel Pit Fossil Site, a UNESCO World Heritage Site at Messel near Darmstadt,
Germany, reveals at least 140 genera, representing more than 36 families. The flora includes occasional
conifer remains (Doliostrobus scales) and numerous angiosperm remains. The following
angiosperm families are represented (of which ten denoted “*” are new records for Messel): Arecaceae,
Alangiaceae (*), Altingiaceae (*), Anacardiaceae (4 genera), ?Apocynaceae, Bignoniaceae, Burseraceae
(*) (2 genera), Cannabaceae (*), Cyclanthaceae, Cyperaceae, Elaeocarpaceae (*), Euphorbiaceae,
Hamamelidaceae (2 genera), Icacinaceae (6 genera), Juglandaceae (3 genera), Lauraceae (c. 4
morphotypes), Leguminosae (c. 5 morphotypes), Magnoliaceae, Mastixiaceae (5 morphotypes),
Menispermaceae (17 morphotypes), Myristicaceae (*), ?Nymphaeales, Nyssaceae, Pentaphylacaceae,
Rhamnaceae (*), Rutaceae (5 morphotypes), Sabiaceae (*), Salicaceae, Sapotaceae, Simaroubaceae,
Tapisciaceae (*), Theaceae, Toricelliaceae (*), Ulmaceae, Vitaceae (7 morphotypes), plus 65 morphotypes
of unknown familial affinity. The genera Berchemia, Mytilaria and Pleiogynium are here recorded
for the first time from the Paleogene. The assemblage indicates a wide range of dispersal strategies
including most modern categories of winged disseminules, pods, capsules, explosive dehiscence, a
single arillate seed and two seed-types with dispersal hairs (one a coma). There is no direct evidence of
epizoochory. In terms of mammalian frugivory the flora contains examples of all potential dietary categories.
Tough and hard materials are abundant and soft material (e.g. in fleshy fruits) is common. Gut
contents preserved in many birds and mammals prove that fruits and seeds played a part in vertebrate
diets and borings in one seed type (Rutaspermum) indicate seed predation by weevils. No fruits or seeds
show evidence of rodent gnawing. Previous quantitative studies suggesting an equable warm and humid
palaeoclimate with some seasonality for Messel are supported by the newly recognised taxa. Judging
from the habit of related living taxa, the vegetation appears to have been a multistratal canopy forest,
including a high proportion of lianas in addition to shrubby to arborescent taxa. Herbaceous components
are also present but relatively underrepresented. Among other large Eocene macrofossil floras,
the Messel assemblage shows overlap with the genera known from the London Clay flora of England
and the Clarno Nut Beds flora of Oregon, but relatively little similarity with floras known from eastern
Asia. Compared with extant floras, the Messel flora includes a temperate component with mostly Asian
endemics, and some genera that are now disjunctly distributed in the Northern Hemisphere. A large
tropical-paratropical component includes genera now confined to the Old World tropics, particularly
southeastern Asia and Malesia, but there are also a few exclusively Neotropical elements.
Fifteen new legume taxa based on fruits and foliage, including 10 Mimosoideae (three Inga spp., two Pithecellobium spp., Acacia, Mimosa, two Stryphnodendron spp., and Piptadenia), three Caesalpinioideae (Chamaechrista, Senna, and Apuleia), and two Papilionoideae (Cladrastis and Robinia), are described from the Eocene San José de la Popa locality, La Carroza Formation, Nuevo León, and the Oligocene Los Ahuehuetes locality, Coatzingo Formation, Puebla, Mexico. Comparing the fruit type of the Leguminosae and the leaf architecture of the family with the fossils here studied, it is possible to confirm the presence of Leguminosae in Mexican territory (= low‐latitude North America) since the Paleogene and to suggest that the family has been an important element of its flora and vegetation through the Cenozoic. The place of origin of the family is uncertain, but the diversification of some lineages through the Tertiary in North America is well supported by the fossil record. Furthermore, as the fossil record is complemented with phylogenetic studies, the importance of North America, including Mexico, as an area of diversification of plants phylogenetically related with European, Asian, and even African ones is further supported. The new fossil legumes are in part consistent with the concept of a Tertiary boreotropical flora that extended southward into Mexico, as well as with the recognition that some taxa likely evolved in low‐latitude North America rather than merely arriving as immigrants from adjacent regions.
Premise of research. The fossil record of Cercis L. needs to be understood in better detail as a basis for reconstructing the evolution for understanding the radiation of Caesalpinoideae. The genus can now be traced back to the late Eocene of western North America on the basis of fossil fruits and foliage from Oregon and Colorado.
Pivotal results. We present a new occurrence of Cercis leaf fossils from Teater Road, Oregon (∼36 Ma), that conforms to the species Cercis parvifolia Lesquereux, previously recognized from Florissant, Colorado (∼34 Ma). Associated pods of Cercis herbmeyeri sp. n. represent the earliest confirmed fossil fruits of Cercis. In their indehiscent pods with a winglike flange along one margin, the fossils correspond to the main clade of Cercis rather than to the phylogenetically distinct extant species Cercis chingii. A review of other occurrences that we accept from the literature reveals that the genus was widespread in the Northern Hemisphere by the Miocene, although some earlier paleobotanical reports must be rejected.
Conclusions. The fossil record indicates that Cercis was established by the late Eocene and had become widespread in the Northern Hemisphere by the Miocene. The late Eocene records have a lamina shape consistent with a mesic habitat but relatively small leaf size, which might indicate adaptation for drying conditions.
The U.S. Gulf Coast has an extensive but poorly dated paleobotanical record. A fossil locality behind the former Red Hot Truck Stop in Meridian, Mississippi, is well-known for its unusually rich biota of late Paleocene and early Eocene mammals, fish, snakes, mollusks, and plants. The latter include palynomorphs, fruits, and leaves, which are found in the basal Bashi Formation and are studied here for the first time. Though generally not well-preserved, the Red Hot leaf flora is significant because it is reliably dated to the first e11.6 million years of the Eocene and possibly lies within the Paleocene-Eocene Thermal Maximum; in contrast, nearly all other Eocene Gulf Coast macrofloras are middle Eocene or uncertain in age. We recognize 18 leaf species and morphotypes, including Lygodium kauffussi (a climbing fern), and representatives of Lauraceae (laurel family), Myrtaceae (guava family), Fabaceae (legumes), Platycarya (Juglandaceae, walnut family), Rhus (Anacardiaceae, sumac family), and a new genus and species of Ochnaceae (ochna family), all consistent with a tropical to subtropical climate. Additionally, two dispersed cuticle morphotypes are described that probably represent a monocot and a liverwort. The occurrence of Platycarya is the first macrofossil record of this Eocene index taxon from the eastern USA and corroborates pollen occurrences from the same strata. The Ochnaceae specimens are currently the only reliable leaf fossils of this distinctly tropical group with ∼30 genera and ∼500 species today; due to their significance, we assign them to a new taxon, Rhabdophyllites diapyros gen. et sp. nov. Most of the recognizable plant taxa are present at, or near, this time in the well-dated sequences of the Rocky Mountain region, indicating their wide North American distribution. The Red Hot flora shows the potential to build a well-dated record of Paleogene floras on the Gulf Coast, improving understanding of plant migration and evolution.
The Neotropical Bowdichia clade (Leguminosae: Papilionoideae) comprises four genera, Bowdichia, Diplotropis, Guianodendron, and Leptolobium, which are sister to the core Genistoid clade. Bowdichia and Diplotropis at one time were treated as a single genus, whereas Guianodendron and Leptolobium have been synonymized with the distantly related Dalbergioid genus Acosmium because of shared radial floral symmetry. We combined and analysed morphological and molecular data including the nuclear ribosomal internal transcribed spacers (ITS; including ITS1/5.8S/ITS2) and two chloroplast DNA (matK, trnL intron) regions in order to evaluate the monophyly of each genus and the Bowdichia clade. A combined parsimony analysis strongly supported the monophyly of Bowdichia, the paraphyly of Diplotropis, and the independent evolution of radial floral symmetry in Guianodendron and Leptolobium. Leptolobium is sister to Bowdichia and Guianodendron is nested within Diplotropis s.l. Diplotropis is here recircumscribed as to encompass the monophyletic Diplotropis sect. Diplotropis and it is suggested that D. sect. Racemosae deserves segregation into a new genus. Radial floral symmetry has been overemphasised in previous classifications by taxonomists who did not recognize its evolutionary lability. This has resulted in non-monophyletic circumscriptions of genera such as Acosmium.
Results of an expanded rbcL study of family-level phylogenetic relationships of Leguminosae are compared with non-molecular evidence that is being accumulated in a "general" data set currently containing 300 characters drawn from various sources, including micro-and macromorphology, anatomy, embryology, chromosome numbers, and DNA rearrangements. The rbcL parsimony analysis included over 300 sequences, representing 77 outgroup genera and 194 genera of legumes, with strongest sampling from Papilionoideae. Characters supporting particular groupings are described, and prospects for combining the two data sets are discussed.
Plant megafossils are described, illustrated and discussed from Powers Clay Pit, occurring in the middle Eocene, Claiborne Group of the Mississippi Embayment in western Tennessee. Twenty six species and eight types of plants, and two species of insect larval cases are represented in this study. They include Lauraceae, Annonaceae, Smilacaceae, Platanaceae, Altingiaceae, Myrtaceae, Fabaceae, Fagaceae, Salicaceae, Moraceae, Rhamnaceae, Sapindaceae, Nyssaceae, Theaceae, Apocynaceae, Rubiaceae, Araliaceae, Oleaceae, entire margin morphotype 1-5, tooth margin morphotype 1, reproductive structure morphotype 1, Folindusia, and Terrindusia. Specimens collected from Powers Pit are compared to those from previous studies from western Tennessee, the Claibome Group in general, and assessed in terms of extant relationships. The extant relationships of plant megafossils described in this study provide clues to the paleoenvironment of western Tennessee during the middle Eocene. The paleoenvironment may have been subtropical accommodating warm tropical to cool temperate plant species.
While many plant species are considered threatened under anthropogenic pressure, it remains uncertain how rapidly we are losing plant species diversity. To fill this gap, we propose a Global Legume Diversity Assessment (GLDA) as the first step of a global plant diversity assessment. Here we describe the concept of GLDA and its feasibility by reviewing relevant approaches and data availability. We conclude that Fabaceae is a good proxy for overall angiosperm diversity in many habitats and that much relevant data for GLDA are available. As indicators of states, we propose comparison of species richness with phylogenetic and functional diversity to obtain an integrated picture of diversity. As indicators of trends, species loss rate and extinction risks should be assessed. Specimen records and plot data provide key resources for assessing legume diversity at a global scale, and distribution modeling based on these records provide key methods for assessing states and trends of legume diversity. GLDA has started in Asia, and we call for a truly global legume diversity assessment by wider geographic collaborations among various scientists.
Resolving the phylogenetic relationships of the deep nodes of papilionoid legumes (Papilionoideae) is essential to understanding the evolutionary history and diversification of this economically and ecologically important legume subfamily. The early-branching papilionoids include mostly Neotropical trees traditionally circumscribed in the tribes Sophoreae and Swartzieae. They are more highly diverse in floral morphology than other groups of Papilionoideae. For many years, phylogenetic analyses of the Papilionoideae could not clearly resolve the relationships of the early-branching lineages due to limited sampling. In the eight years since the publication of Legumes of the World, we have seen an extraordinary wealth of new molecular data for the study of Papilionoideae phylogeny, enabling increasingly greater resolution and many surprises. This study draws on recent molecular phylogenetic studies and a new comprehensive Bayesian phylogenetic analysis of 668 plastid matK sequences. The present matK phylogeny resolves the deep-branching relationships of the papilionoids with increased support for many clades, and suggests that taxonomic realignments of some genera and of numerous tribes are necessary. The potentially earliest-branching papilionoids fall within an ADA clade, which includes the recircumscribed monophyletic tribes Angylocalyceae, Dipterygeae, and Amburanae. The genera Aldina and Amphimas represent two of the nine main but as yet unresolved lineages comprising the large 50-kb inversion clade. The quinolizidine-alkaloid-accumulating Genistoid s.l. clade is expanded to include Dermatophyllum and a strongly supported and newly circumscribed tribe Ormosieae. Sophoreae and Swartzieae are dramatically reorganized so as to comprise monophyletic groups within the Core Genistoid clade and outside the 50-kb inversion clade, respectively. Acosmium is excluded from the Genistoids s.l. and strongly resolved within the newly circumscribed tribe Dalbergieae. By providing a better resolved phylogeny of the earliest-branching papilionoids, this study, in combination with other recent evidence, will lead to a more stable phylogenetic classification of the Papilionoideae.
An early Eocene (52 ± 2 Ma) flora from the Mwadui kimberlite pipe in Tanzania includes ten leaf morphotypes, small seeds, fossil wood putatively related to Cynometra (Detarieae, Fabaceae), and a sparse palynoflora. The leaf flora is characterised by microphyllous and notophyllous entire margined leaves that are suggested to be related to the Euphorbiaceae and Fabaceae, although many cannot be firmly placed in modern families. The wood is the oldest member of Cynometroxylon and confirms that the Detarieae were diverse by the early Paleogene. The palynoflora is dominated by Ailanthipites daedaleus and Triporopollenites mwaduiensis with lesser amounts of small tricolpate (Tricolpites) and monosulcate (Lilliacidites) grains together with spores (Cyathidites spp., Triporoletes laevigatus) and freshwater algal cysts. Other components of the palynoresidue include abundant charcoalified tracheids and fungal hyphae. The low diversity and sparse palynoflora suggests a restricted catchment with little input from the regional vegetation. The sediments accumulated in a freshwater lacustrine environment with palynological input from the crater walls that were covered by low diversity vegetation. This is supported by the leaf floras. Although the leaf floras are more diverse with nine morphotypes identified, the small leaves (microphyll to notophyll) suggest a water-limited palaeoenvironment. This is supported by the low diversity and abundance of fern and bryophyte spores. The presence of a single wood taxon not only indicates that there were large trees around the crater-lake but that the aboreal component was of low diversity. These observations suggest an open woodland-like setting, while the taxonomic affinities of the wood (Cynometra) suggest a humid microclimate possibly with marked wet–dry seasonal contrasts.
Faunas recovered from the middle Eocene Tepee Trail Formation in the North Fork of Owl Creek area include the following: The lower part of the Tepee Trail Formation (“Holy City beds”) produced a fauna containing taxa that until now have only been reported from the Bridgerian (Sciuravus nitidus, Viverravus sp. cf. V. sicarius, HelalestesT), as well as taxa reported only from the Uintan (Epihippus and Forstercooperia) and is considered a possible equivalent of the earliest Uintan. The fauna from the middle and upper Tepee Trail is equivalent to Uinta “A” or “B” faunas based on the presence of Epihippus, Forstercooperia, Amynodon, Hylomeryx and Achaenodon. The first known fauna from the Uintan part of the Wiggins Formation is approximately equivalent to those of the Uinta “B” based on the presence of relatively primitive primates (Microsyops and cf. Hemiacodon), exclusively paramyid rodents, and the absence of eomyids, canids and camelids. The stratigraphically highest beds in the Wiggins Formation may contain faunas equivalent to the Uinta “C.” The Tepee Trail and Wiggins formations were deposited in the Anomaly 21 Chron.
A number of fossil fruits/seeds are known from the different Tertiary sediments in India ranging from the Maastrichtian-Danian (Palaeocene) to the Pliocene-Pleistocene. Present account embodies the listing of some well-known fossil fruits/seeds from the Indian Tertiary and an attempt has been made to throw light on their palaeoecological, palaeophytogeographical and the evolutionary significance. Most of the known monocot fossils belong particularly to the family Arecaceae from the Maastrichtian-Danian Deccan Intertrappean beds of India. In the dicots, quite a few fossil fruits/seeds of family Lythraceae are described only from the Maastrichtian-Danian, while the fabaceous fruits/seeds are described in a large number mostly from the Oligocene to Miocene. The families viz., Arecaceae, Burseraceae, Combretaceae, Nyssaceae, Polygonaceae, Rhamnaceae, Rubiaceae and Sapindaceae occur in the Neogene sediments. However, the paucity of fossil fruits/seeds precludes any definite analysis or comments on their palaeobotanical characteristics. Most of the fossil fruits are drupaceous or capsular while fabaceous fruits are lomentum or legume. types. The fibrous nature of mesocarp in Arecaceous fruits suggests their dispersal through water, such plants might be growing in the coastal areas or near the other water bodies. The capsular or the other fruits with thin pericarp might belong to the inland terrestrial zones. Many fruits of uncertain affinities, e.g. Sahniocarpon, Wingospermocarpon, Enigmocarpon and Viracarpon pose interesting questions about the evolution of angiosperms during the Tertiary in India. Further investigations are needed to ascertain the taxonomy of fossil fruits/seeds, to ascribe them to respective families. Key-words—
Podocarpium (Fabaceae), characterized by single seeded pods and paripinnate compound leaves, is well known as an extinct legume genus having extensive fossil occurrences from the Miocene of Central Europe and eastern Asia. However, the Palaeogene unambiguous megafossils are quite scarce, especially the Oligocene record from eastern Asia, which heavily impedes our understanding of early dispersal patterns and infrageneric relationships of this enigmatic genus. Here, we described dozens of legume specimens from the Oligocene Ningming Formation of Guangxi in South China, the Early Miocene Guide Group of Qinghai in Northwest China and the Middle–Late Miocene Shengxian Formation of Zhejiang in Southeast China as Podocarpium podocarpum (A. Braun) Herendeen based on extremely similar fruit characters. Meanwhile, we reexamined variation in fruit morphology among the previously reported fruits of Eurasia and present legumes as a basis for interpreting the infrageneric relationship and subfamily affinity of Podocarpium. The high similarities presented by these fossil fruits support the previous recognition of the specimens from the Oligocene–Miocene of Central Europe and the Miocene– Pliocene of eastern Asia as P. podocarpum, but such a low species diversity of Podocarpium appears to indicate a bradytelic morphological evolution for this whole ancient lineage through geologic time. Moreover, judging from seed orientation as well as seed and fruit comparative sizes, the oblong seed is parallel to the long axis of the fruit and its placentation is near the apex of the seed chamber, which favor the previous assignment of Podocarpium to the subfamily Caesalpinioideae. Additionally, we speculated that this extinct genus may prefer a warm and humid (or mildly arid) environment by plotting the megafossil localities on the overall Eocene, Oligocene and Miocene palaeoclimate maps based on continental drift. The Oligocene occurrence from the Ningming Formation in Guangxi, South China sheds new light on the historical biogeographical pattern between Central Europe and eastern Asia, i.e. after the probable origin in low latitude tropic coastal regions of southernmost South China (i.e. Hainan) by the Middle Eocene, Podocarpium may subsequently disperse into Guangxi and then Europe via a probable low-latitude land connection located among the Tethys and Paratethys seas to the southwest of Eurasia in the Early Oligocene, independent of the gradual closure of the Turgai Strait in the middle-high latitudes during the Oligocene.
Isolated legume fruits from the early–middle Miocene Shimo Formation of the Uchiura Group in Takahama Town, Fukui Prefecture, central Japan, are described in this paper. They are unique in yielding 1-coiled or curved and terete–moniliform shapes with both simple sutures constricting uniformly. A new fossil-species, Leguminocarpum oguruiensis, is designated here. These legume specimens occur together with a number of molluscan fossils that indicate tropical–subtropical shallow marine conditions at the warmest time period during the mid-Miocene Climatic Optimum. The species was probably dispersed by the oceanic currents from southerly areas and inhabited areas with coastal vegetation where warm-temperate forest elements dominated.
Legume fruits from the Eocene of Tennessee and Wyoming and the Miocene of Idaho are described and assigned to Caesalpinia subgenus Mezoneuron (Caesalpinioideae), an extant Paleotropical taxon that does not occur in North or South America today. Morphological and anatomical details of the fruits are used in evaluating their systematic relationships. The features of the fossil fruits are accommodated only within this extant subgenus. These fossils represent the only reliable known occurrence of C. subgenus Mezoneuron in the paleobotanical record. These fossils suggest that subgenus Mezoneuron was distinct from subgenus Caesalpinia by the Middle Eocene. Further, they document the widespread occurrence of this currently Paleotropical group for at least 30 million years in North America.
Compressed mimosoid inflorescences from a Paleocene-Eocene boundary locality in western Tennessee are the earliest fossil evidence of the subfamily. The discovery confirms the antiquity of a suite of characters that has been considered primitive based on the comparative morphology of modern mimosoids. The fossil characters are also consistent with the suggested close relationship (ancestral or sister group) between the subfamily Mimosoideae and the Dimorphandra group of the tribe Caesalpinieae (subfamily Caesalpinioideae). These flowers show little change in morphology or size in the basal to Upper Eocene interval.
New legume fossils can provide an historical perspective of their early evolution and biogeographic history. Three legume species, Albizia ningmingensis sp. nov., Leguminocarpum sp. 1 and Leguminocarpum sp. 2, from the Oligocene Ningming Formation of Guangxi, South China, are described on the basis of morphological and/or anatomical characteristics. Albizia ningmingensis sp. nov. bears a close resemblance to the extant species A. kalkora in morphology and anatomy and represents a reliable occurrence of Albizia in the Oligocene deposits of China. An incomplete fruit fossil is described as Leguminocarpum sp. 1, predominantly on the basis of anatomical characteristics. Fruits of Leguminocarpum sp. 2 are straight and strongly asymmetrical, with one straight suture and the other strongly constricted. The occurrence of Albizia fruits indicate that Albizia elements existed in the South China during the Oligocene. Our legume fossils, together with earlier records of three Bauhinia species, indicate that a flora with the unusual abundance of legumes was present in South China in the Oligocene. The legumes from the Ningming Formation, having a relatively high diversity, can contribute to the palaeoclimatic interpretation and indicate that the Oligocene Ningming flora most likely lived in a tropical-to-warm subtropical climate.
Parallel to the Krishna river course, a set of ENE to WSW trending brittle-ductile shear zones affecting the Neoarchaean pink porphyritic granite remains athwart to the NW-SE tectonic fabric of the Eastern Dharwar Craton (EDC) in Raichur and Gulbarga districts, Karnataka, India. These zones are not only manifested by intense mylonitization, brecciation and fracturing, but also witness several episodes of mafic and felsic intrusions. At Machanur, Raichur district a 5 km long and 400 m wide shear zone hosts copper, gold and REE mineralization both in specularite-rich hydrothermal veins and as disseminations within the dolerite dykes. The mineralization is associated with well-developed zones of hydrothermal alteration in the form of propylitization, carbonatization, epidotization and silicification with patches of strong iron-staining and fracture-filled iron solution dominantly in the footwall side. Due to similarity with many iron oxide- copper-gold-type deposits, this prospect in Machanur is interpreted as iron oxide-copper-gold-type mineralization.
The report area includes about 430km² in the SE Absaroka Range and SW Bighorn Basin, Hot Springs County, Wyo. It is bounded on the S by the Wind River Indian Reservation (along the S Fork of Owl Creek), and on the N by Grass Creek. The E part of the area is dominated by rugged badland topography; whereas, the western part is characterized by mountainous terrain; local relief in the area is approx 1200m. Exposed sedimentary rocks are >3500m thick and include rocks of Devonian through Holocene age. Paleozoic rocks are restricted to the N margin of the Owl Creek Mountains where they are overlapped by Tertiary volcaniclastics. Mesozoic rocks dip gently N-ward off the Owl Creek Mountains and are also exposed at the E margin of the Absaroka volcanic field, where they are unconformably overlain by essentially flat lying lower Eocene strata. Tertiary rocks are present throughout most of the report area. Four formations are recognized: the Willwood Formation of early Eocene age, and the Aycross, Tepee Trail, and Wiggins Formations of middle Eocene age. Each of these units is separated from older rocks by erosional or angular unconformities in the mapped area, and all, except the Willwood, are dominantly volcaniclastic. Quaternary deposits include alluvium, colluvium, landslide detritus, and large and small detached masses of Eocene rocks.-from Author
Bowerbank (1840) proposed Leguminosites for fossil seeds with uncertain affinities within Leguminosae Juss., but later workers demonstrated that his voucher specimens represent seeds of Magnolia L., Icacinicarya E. Reid & M. Chandler, genera of Sapindaceae Juss., and other non-legumes (e.g., Carpolithus Brongn.). Thus, Leguminosites, unless conserved, must be applied to non-legume entities under Art. 7.1 of the Vienna Code. Although more than 300 species of Leguminosites variously used for fossil legume leaves, fruits and seeds with uncertain affinities have been described by subsequent palaeobotanists, the legume identity of the majority of species names awaits confirmation by reinvestigation of the original materials and discovery of better preserved materials. Hence, conservation of Leguminosites may be premature for nomenclatural stability. It is suggested that the application of the fossil-generic name Leguminosites to isolated remains of more than one organ type should be avoided if the congeneric evidence for these organs is lacking. Therefore, isolated fossil legume leaves, fruits and seeds with uncertain affinities can be placed under at least three different fossil-generic names respectively in spite of the fact that they may, at least in part, apply to the same organism.It appears to be better to abandon Leguminosites and propose a new generic name for fossil legume seeds with uncertain affinities. Leguminocarpum Dotzler (1937) has priority over Legumino carpon Göpp. ex Pálfalvy (1951) for fossil legume fruits with uncertain affinities. Leguminophyllum A. Escalup-Bassi (1971) and Parvileguminophyllum Herend. & Dilcher (1990), which may be synonymous, can be used for fossil legume leaves with uncertain affinities.
The Wapiti and Aycross formations are lateral and time equivalent units. Use of the name Pitchfork Formation is abandoned. Based on paleomagnetic studies, flows on Ptarmigan and Carter mountains are assigned to the Wapiti Formation (Jim Mountain Member?) and an unnamed sequence rather than to the Trout Peak Trachyandesite. The Blue Point marker overlies the Aycross and Wapiti formations (and the unnamed sequence), and underlies the Tepee Trail and Wiggins formations. The Tepee Trail Formation intertongues with the lower part of the Wiggins Formation in the Greybull Valley area, and is overlain by the Wiggins Formation to the S. The fauna from the Wapiti Formation compares with those of the Bridger 'B.' The faunas from the 'turtle-lake beds' (unnamed sequence) and from the Blue Point marker appear to be transitional between those of the Bridger 'B' and 'C'. Two new species, Pseudotomus sundelli and Hyopsodus tonksi, are described. The Wapiti Formation was probably deposited during normal event 21 of the magnetic anomaly scale. The unnamed sequence and the Blue Point marker may have been deposited during a short reversed episode within normal event 21.-Author
The establishment of modern terrestrial life is indissociable from angiosperm evolution. While available molecular clock estimates of angiosperm age range from the Paleozoic to the Late Cretaceous, the fossil record is consistent with angiosperm diversification in the Early Cretaceous.
The time‐frame of angiosperm evolution is here estimated using a sample representing 87% of families and sequences of five plastid and nuclear markers, implementing penalized likelihood and Bayesian relaxed clocks. A literature‐based review of the palaeontological record yielded calibrations for 137 phylogenetic nodes. The angiosperm crown age was bound within a confidence interval calculated with a method that considers the fossil record of the group.
An Early Cretaceous crown angiosperm age was estimated with high confidence. Magnoliidae, Monocotyledoneae and Eudicotyledoneae diversified synchronously 135–130 million yr ago (Ma); Pentapetalae is 126–121 Ma; and Rosidae (123–115 Ma) preceded Asteridae (119–110 Ma). Family stem ages are continuously distributed between c . 140 and 20 Ma.
This time‐frame documents an early phylogenetic proliferation that led to the establishment of major angiosperm lineages, and the origin of over half of extant families, in the Cretaceous. While substantial amounts of angiosperm morphological and functional diversity have deep evolutionary roots, extant species richness was probably acquired later.
Five types of Late Eocene woods from western Nebraska are described. Three of the woods have an anatomy comparable to extant genera: Robinia (Leguminosae), Zelkova (Ulmaceae), and Prunus s.l. (Rosaceae). The Robinia wood is the earliest wood record for the genus. One wood has a suite of features most similar to that found in the Juglandaceae, but its combination of characters is not diagnostic to tribe. This material indicates that unique character combinations occurred within the Juglandaceae during the Late Eocene. One wood is likely a legume, but it has a combination of features that occur today in at least four other families, and so it is not assigned to a family. As a group these woods indicate that climate in the Late Eocene of Nebraska was seasonal—the Robinia and Zelkova woods are markedly ring porous, the Juglandaceae-like wood is semi-ring porous, the two diffuse porous woods have small diameter vessels and a high vessel density.