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Cenozoic High Latitude Heterochroneity of Southern Hemisphere Marine Faunas
Abstract
Discovery of 11 genera, in five classes within the Mollusca, Echinodermata, and Arthropoda in upper Eocene rocks on Seymour
Island, Antarctica, previously known only from Late Cenozoic in mid-latitudes, suggests that the high latitude region of the
Southern Hemisphere acted as a center of origin and dispersal for a broad spectrum of taxa. Precursors to modern deep- and
shallow-water mid-latitude forms evolved and flourished in the high latitudes until conditions in lower latitudes favored
their dispersal. These observations of Antarctic marine invertebrates corroborate those recently made about terrestrial mammals
and plants in the Arctic.
... Because of the overall uniformity of the faunas, it is considered to represent a single broad biogeographic province, designated by Zinsmeister (1979) as the Weddellian Province. It appears that this high latitude region acted as a centre of origin and dispersal for a broad spectrum of taxa, including molluscs (Zinsmeister and Feldmann, 1984; Crame, 1992). Late Cenozoic. ...
... physical destruction of fine-grained substrates; Crame, 1996) associated with glaciations. It would appear most likely that most of these affinities and relationships (Fig. 3) are the product of high-latitude radiations in Quaternary times, since they do not reflect ancient similarities (pointed out by Zinsmeister and Feldmann, 1984; and Crame, 1996) during the Palaeogene when the two regions formed part of the Weddellian Province. ...
Palaeontological studies on postglacial molluscan faunas from marine deposits located along the northern coast of the Beagle Channel (lat. 54°55'S, long. 68°34'-67°11'W) showed differences of various molluscan assemblages during a period of climatic stability after deglaciation. Oceanographic changes, different local environmental conditions and/or episodes of minor climatic fluctuations are pointed out as causes for the variations in faunal composition. Comparison with Quaternary molluscs from Antarctica showed that these palaeofaunas overlap slightly at the species level, but have a considerable number of genera (23%) and families (50%) in common. These affinities and relationships are better explained on the basis of more recent migrating taxa than by ancient connections when the two regions formed part of the Weddellian Province.
... Beginning in the late Eocene, declining temperatures accompanied by reduced shelf area due to glaciation altered the geographic and bathymetric ranges of a variety of antarctic taxa (Zinsmeister and Feldmann, 1984;Clarke and Crame, 1992;Meyer and Oji, 1993;Blake and Aronson, 1998). The effects of changing climate on fish and crabs are of particular interest because of their importance as predators in benthic communities. ...
... (B) An isocrinid crinoid, Metacrinus fossilis, from the La Meseta Formation. Although the genus Metacrinus may have evolved in shallow water in Antarctica during the Eocene and then spread to deep-water habitats elsewhere (Zinsmeister and Feldmann, 1984;Meyer and Oji, 1993), isocrinids in general have been excluded from shallow water since the middle Cretaceous (Oji, 1985). Unlike other isocrinids, M. fossilis had short, tapered stalks, which they probably used to anchor themselves in soft sediments. ...
The cover of noncoralline macroalgae increased dramatically on Caribbean reefs during the 1980s and 1990s. A top-down hypothesis, based largely on observations at Discovery Bay, Jamaica, is that this change was caused by reduced herbivory. Herbivory was reduced by the regional mass mortality of the echinoid Diadema antillarum in 1983-1984 and by human exploitation of herbivorous fishes. An alternative, bottom-up explanation is that nutrient concentrations increased past threshold levels for algal blooms. Surveys at Discovery Bay showed that Diadema reappeared on the shallow fore reef after 1996, accompanied by drastically reduced macroalgal cover. There is no evidence to suggest that nutrient levels declined at the same time. These observations corroborate predictions of the top-down hypothesis, and they confirm the key role of herbivory in structuring shallow reef communities of the Caribbean.
... Because of the overall uniformity of the faunas, it is considered to represent a single broad biogeographic province, designated by Zinsmeister (1979) as the Weddellian Province. It appears that this high latitude region acted as a centre of origin and dispersal for a broad spectrum of taxa, including molluscs (Zinsmeister and Feldmann, 1984;Crame, 1992). ...
... physical destruction of fine-grained substrates; Crame, 1996) associated with glaciations. It would appear most likely that most of these affinities and relationships (Fig. 3) are the product of high-latitude radiations in Quaternary times, since they do not reflect ancient similarities (pointed out by Zinsmeister and Feldmann, 1984;and Crame, 1996) during the Palaeogene when the two regions formed part of the Weddellian Province. ...
Palaeontological studies on postglacial molluscan faunas from marine deposits located along the northern coast of the Beagle Channel (lat. 54°55’S, long. 68°34’-67°11’W) showed differences of various molluscan assemblages during a period of climatic stability after deglaciation. Oceanographic changes, different local environmental conditions and/or episodes of minor climatic fluctuations are pointed out as causes for the variations in faunal composition. Comparison with Quaternary molluscs from Antarctica showed that these palaeofaunas overlap slightly at the species level, but have a considerable number of genera (23%) and families (50%) in common. These affinities and relationships are better explained on the basis of more recent migrating taxa than by ancient connections when the two regions formed part of the Weddellian Province.
... Further refugia could have come from the freezing of microorganisms and benthic larvae within sea ice (Schnack-Schiel et al., 2001) or benthic sediments (Jiang et al., 2012), with subsequent thawing and recolonisation of the seafloor. With glacial expansion, animals can migrate to the slope or the deep sea (Brandt, 1992;Brey et al., 1996;Zinsmeister & Feldmann, 1984), find refuge beneath some floating ice shelves, or in areas where grounded ice failed to reach the edge of the continental shelf (Post et al., 2014). With an extreme global glaciation, such as a snowball or partial snowball Earth, these effects would be even more severe, and shallow water habitats, along with the benthos, would have been decimated. ...
The timing of the first appearance of animals is of crucial importance for understanding the evolution of life on Earth. Although the fossil record places the earliest metazoans at 572–602 Ma, molecular clock studies suggest a far earlier origination, as far back as ~850 Ma. The difference in these dates would place the rise of animal life into a time period punctuated by multiple colossal, potentially global, glacial events. Although the two schools of thought debate the limitations of each other's methods, little time has been dedicated to how animal life might have survived if it did arise before or during these global glacial periods. The history of recent polar biota shows that organisms have found ways of persisting on and around the ice of the Antarctic continent throughout the Last Glacial Maximum (33–14 Ka), with some endemic species present before the breakup of Gondwana (180–23 Ma). Here we discuss the survival strategies and habitats of modern polar marine organisms in environments analogous to those that could have existed during Neoproterozoic glaciations. We discuss how, despite the apparent harshness of many ice covered, sub-zero, Antarctic marine habitats, animal life thrives on, in and under the ice. Ice dominated systems and processes make some local environments more habitable through water circulation, oxygenation, terrigenous nutrient input and novel habitats. We consider how the physical conditions of Neoproterozoic glaciations would likely have dramatically impacted conditions for potential life in the shallows and erased any possible fossil evidence from the continental shelves. The recent glacial cycle has driven the evolution of Antarctica's unique fauna by acting as a “diversity pump,” and the same could be true for the late Proterozoic and the evolution of animal life on Earth, and the existence of life elsewhere in the universe on icy worlds or moons.
... The existence of such a dispersal route has been suggested for other freshwater decapod crustaceans (Feldmann, 1984;Zinsmeister & Feldmann, 1984;Feldmann & McLay, 1993). This distributional pattern, i.e., a high southern latitude origin of the taxon and dispersal through Antarctica and into South America, may be similar to that of the freshwater squat lobster Aegla Dana, 1852 (Anomura) (Feldmann, 1984). ...
The Infraorder Astacidea comprises four superfamilies of decapod crustaceans: the freshwater Astacoidea and Parastacoidea and the marine Enoplometopoidea and Nephropoidea. The gill morphology of four species of crayfishes belonging to Astacoidea and Parastacoidea, two coral reef species of Enoplometopoidea, and 2 deep-water species of Nephropoidea are described and illustrated for comparisons and to determine characters characteristic to members of the family Parastacidae (Parastacoidea) from New Guinea. Morphology of the arthrobranchs and pleurobranchs were similar among all species, having a single stem with filament, but podobranchs of the parastacoideans differed from those of Astacoidea, being corrugated and tubular and having filaments. The astacoidean P. virginalis had a plate-like lamella with filament. The two nephropoid and two enoplometopoid species were similar to each other; their podobranch had a flat blade-like lamella without a filament and a shaft with a filament. The gill formulae of the New Guinea species of Cherax were the same as those of the Australian congeners, but the formula of the New Zealand Paranephrops planifronsWhite, 1842 was the same as those of the South American parastacids.
... Similarly, nudipleuran evolution is proposed to have taken place around the cooling of Antarctica about 40 or 30 Ma prior to invasion of temperate and tropical seas along northward flowing currents of Antarctic origin (see Göbbeler & Klussmann-Kolb, 2010). Fossil evidence also suggests submergence of shallow-water Antarctic bivalves, gastropods, asteroids, crinoids and decapods into the deep sea during this period (Zinsmeister & Feldmann, 1984). Although the timing remains unclear, molecular evidence indicates that palinurid spiny lobsters originated around Antarctica, invading deep-sea habitats from shallower rocky reefs and then radiating (Tsang et al., 2009). ...
Bathymetric biodiversity patterns of marine benthic invertebrates and demersal fishes have been identified in the extant fauna of the deep continental margins. Depth zonation is widespread and evident through a transition between shelf and slope fauna from the shelf break to 1000 m, and a transition between slope and abyssal fauna from 2000 to 3000 m; these transitions are characterised by high species turnover. A unimodal pattern of diversity with depth peaks between 1000 and 3000 m, despite the relatively low area represented by these depths. Zonation is thought to result from the colonisation of the deep sea by shallow-water organisms following multiple mass extinction events throughout the Phanerozoic. The effects of low temperature and high pressure act across hierarchical levels of biological organisation and appear sufficient to limit the distributions of such shallow-water species. Hydrostatic pressures of bathyal depths have consistently been identified experimentally as the maximum tolerated by shallow-water and upper bathyal benthic invertebrates at in situ temperatures, and adaptation appears required for passage to deeper water in both benthic invertebrates and demersal fishes. Together, this suggests that a hyperbaric and thermal physiological bottleneck at bathyal depths contributes to bathymetric zonation. The peak of the unimodal diversity–depth pattern typically occurs at these depths even though the area represented by these depths is relatively low. Although it is recognised that, over long evolutionary time scales, shallow-water diversity patterns are driven by speciation, little consideration has been given to the potential implications for species distribution patterns with depth. Molecular and morphological evidence indicates that cool bathyal waters are the primary site of adaptive radiation in the deep sea, and we hypothesise that bathymetric variation in speciation rates could drive the unimodal diversity–depth pattern over time. Thermal effects on metabolic-rate-dependent mutation and on generation times have been proposed to drive differences in speciation rates, which result in modern latitudinal biodiversity patterns over time. Clearly, this thermal mechanism alone cannot explain bathymetric patterns since temperature generally decreases with depth. We hypothesise that demonstrated physiological effects of high hydrostatic pressure and low temperature at bathyal depths, acting on shallow-water taxa invading the deep sea, may invoke a stress–evolution mechanism by increasing mutagenic activity in germ cells, by inactivating canalisation during embryonic or larval development, by releasing hidden variation or mutagenic activity, or by activating or releasing transposable elements in larvae or adults. In this scenario, increased variation at a physiological bottleneck at bathyal depths results in elevated speciation rate. Adaptation that increases tolerance to high hydrostatic pressure and low temperature allows colonisation of abyssal depths and reduces the stress–evolution response, consequently returning speciation of deeper taxa to the background rate. Over time this mechanism could contribute to the unimodal diversity–depth pattern.
... This indicates that polar submergences and/or emergences occurred during the evolutionary history of the genus, possibly following the oscillations of shelf ice extension. Connections between the Antarctic shelf and the deep sea are also facilitated by the exceptionally deep continental shelf (on average four times deeper than in other continents) coupled with submerging Antarctic bottom water and emerging circumpolar deep water (Menzies et al. 1979;Zinsmeister and Feldmann 1984;Clarke and Crame 1989;Strugnell et al. 2011). ...
The amphipod genus Epimeria is very speciose in Antarctic waters. Although their brooding biology, massive and heavily calcified body predict low dispersal capabilities, many Epimeria species are documented to have circum-Antarctic distributions. However, these distribution records are inevitably dependent on the morphological species definition. Yet, recent DNA evidence suggests that some of these Epimeria species may be complexes of species with restricted distributions. Mitochondrial COI and nuclear 28S rDNA sequence data were used to infer evolutionary relationships among 16 nominal Epimeria species from the Antarctic Peninsula, the eastern Weddell Sea and the Adélie Coast. Based on this phylogenetic framework, we used morphology and the DNA-based methods GMYC, bPTP and BPP to investigate species boundaries, in order to revise the diversity and distribution patterns within the genus. Most of the studied species appeared to be complexes of pseudocryptic species, presenting small and previously overlooked morphological differences. Altogether, 25 lineages were identified as putative new species, increasing twofold the actual number of Antarctic Epimeria species. Whereas most of the species may be geographically restricted to one of the three studied regions, some still have very wide distribution ranges, hence suggesting a potential for large-scale dispersal.
... Prowadzone w rozwa¿anym rejonie Antarktyki badania paleobiologiczne pozwoli³y na kompleksow¹ analizê zespo³ów organizmów kopalnych, maj¹cych istotne znaczenie dla korelacji wiekowej, fluktuacji klimatycznych oraz rekonstrukcji paleooerodowiskowych i paleobiogeograficznych (Zinsmeister & Feldmann, 1984;GaŸdzicki i in., 1992;Dzik & GaŸdzicki, 2001;Birkenmajer i in., 2005;Ivany i in., 2008;Francis i in., 2006Francis i in., , 2009Beu, 2009;Florindo & Siegert, 2009). Dog³êbne poznanie uwarunkowañ, które doprowadzi³y do termicznej izolacji i w konsekwencji zlodowacenia Antarktydy na prze³omie eocenu i oligocenu (ok. ...
... Another theory is that since the onset of glacial climates, Antarctica may have acted as a center of origin for deep-sea taxa, with Antarctic shelf taxa moving into deepwater as a result of climatic deterioration during glaciation periods and the subsequent loss of shallow-water habitat (Zinsmeister and Feldmann 1984;Crame 1993;Rogers 2000;Briggs 2003;Brandt et al. 2007;Strugnell et al. 2008). Range expansion of Antarctic marine organisms into the Southern Ocean followed the development of the Antarctic Circumpolar Current (ACC;~33.8 ...
Cenozoic climate change, tectonics and diversification in the deep-sea: evolution of diversity in the gastropod family Solariellidae (Trochoidea)
S. T. Williams1, L. M. Smith1, D. G. Herbert2, B. A. Marshall3, A. Warén4, S. Kiel5, P. Dyal1, K. Linse6, C. Vilvens7, and Y. Kano8
1 Natural History Museum, Cromwell Road, London, SW7 5BD, United Kingdom. Email: s.williams@nhm.ac.uk ; l.smith@nhm.ac.uk; p.dyal@nhm.ac.uk;
2 KwaZulu-Natal Museum, P. Bag 9070, Pietermaritzburg, 3200, South Africa and School of Life Sciences, University of KwaZulu-Natal, Pietermaritzburg, 3206, South Africa. Email: dherbert@nmsa.org.za;
3 Museum of New Zealand Te Papa Tongarewa, Post Office Box 467, Wellington, New Zealand. Email: bruce.marshall@tepapa.govt.nz ;
4 Swedish Museum of Natural History, Box 50007, SE-10405 Stockholm, Sweden Email: anders.waren@nrm.se;
5 Georg-August Universität Göttingen, Geowissenschaftliches Zentrum, Abteilung Geobiologie and Courant Research Center Geobiology, Goldschmidtstr. 3, 37077 Göttingen, Germany. Email: skiel@uni-goettingen.de;
6 British Antarctic Survey, High Cross, Madingley Road, Cambridge, CB3 0ET, UK. Email: kl@bas.ac.uk;
7 Scientific Collaborator, Muséum national d'Histoire naturelle, Rue Buffon 55, 75231 Paris Cedex 05, France. Email: claude.vilvens@hepl.be;
8 Department of Marine Ecosystems Dynamics, Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8564, Japan. Email: kano@aori.u-tokyo.ac.jp
The modern Indo-West Pacific Ocean (IWP) is the largest biogeographic marine province and is renowned as a hotspot for biodiversity. A maximum, in terms of species richness, is observed for many shallow-water marine organisms in the central IWP, with biodiversity declining with increasing distance from the centre. Recent expeditions have also revealed high levels of biodiversity among deep-sea gastropod molluscs. While many hypotheses exist about the mechanisms that may have led to the present high biodiversity levels in shallow-water IWP communities, little is known about the age or origin of tropical deep-sea biodiversity. We used a deep-sea radiation of vetigastropods as a tractable model to test key hypotheses about origins and to determine the factors driving diversification in the deep sea. We show that an abrupt period of global warming during the Palaeocene Eocene Thermal Maximum leaves no molecular record of change in diversification rate in solariellids. Conversely, diversification in a major clade is congruent with a period of global cooling at the Eocene-Oligocene transition approximately 33.7 Mya. Increased nutrients made available by contemporaneous changes to erosion, ocean circulation, tectonic events and upwelling may explain increased diversification, suggesting that food availability may have been a factor limiting exploitation of deep-sea habitats.
... Beania Johnston and Malakosaria Goldstein, representatives of the family Savignyellidae and ditaxiporine catenicellids occur in the Recent seas and they pre− dominate in the Indo−West Pacific, Atlantic and Southwest Pacific and Australasia. Presence of the new bryozoan records in the Eocene of the La Meseta Formation (Hara 2001(Hara , 2002, shows that Antarctic was an important centre of origin of bryo− zoan taxa during the Paleocene-Eocene cheilostome turnover (Zinsmeister and Feldmann 1984;Bottjer and Jabłoński 1988). ...
The loose, small zooecia of the cheilostome bryozoans have been discovered in the lowermost part of the LaMeseta Formation on Seymour (Marambio) Island. They systemati− cally include the representatives of Beanidae Canu et Bassler, Catenicellidae Busk, Savi− gnyellidae Levinsen, and Calwelliidae MacGillivray. The bryozoan assemblage is comprised of separate, small−sized internal moulds dominated by distinct, boat−shaped zooecia belonging to Beania, scarce, unizooidal internodes tentatively included into a ditaxiporine catenicellid ?Vasignyella, and representative of the family Savignyellidae. A few branched segments composed of multiserial zooecia arranged back to back were tentatively incorporated into ?Malakosaria. Beania, marks the oldest fossil record, whereas representatives of Savignyelli− dae along with ditaxiporine catenicellid and ?Malakosaria are for the first time reported from Antarctica. The relationship between the taxonomic composition, colony growth−patterns rep− resented by membraniporiform/petraliform, catenicelliform and cellariform, along with asso− ciated biota and sedimentary structures of the LaMeseta Formation implies nearshore environ− ment, with considerable wave action, and warm climatic conditions.
... The Antarctic shelf fauna has been strongly influenced by the expansion and retreat of the Antarctic ice sheets on glacial–interglacial time scales (Clarke et al. 1992, Thatje et al. 2005). The expansion of the ice sheets across the continental shelf during glacial periods largely eradicated the available shelf habitats and evidence suggests that these shelf fauna may have migrated to either the Antarctic slope or the deep sea (e.g. Zinmeister & Feldmann 1984, Brandt 1991, Brey et al. 1996). In some regions, however, shelf fauna may have found refugia during glacial periods beneath floating ice shelves or small ice-free areas in regions where grounded ice did not advance to the edge of the continental shelf. ...
... It is possible that these species, with N. rylandae, evolved from the same stock as the New Zealand Neothyris but that the ancestor was common to the mid-Tertiary of the Southern Ocean. Zinsmeister (1982Zinsmeister ( , 1984 suggests that the high latitude region of the southern hemisphere acted as a centre of origin and dispersal for a broad spectrum of taxa. Precursors to modem deep and shallow water mid-latitude forms evolved and flourished in the high latitudes until conditions in lower latitudes favoured their dispersal. ...
The terebratulid brachiopod, Neothyris rylalldae sp. nov., is described from the Pliocene Roe Calcarenite in the Eucla Basin of southern Australia. This is the earliest record of the genus from Australia, all previous records being of extant species. Neothyris is also recorded from the Miocene to Recent of New Zealand and Antarctica.
... They concluded that, given this heterochroneity, as well as the large land mass of the Arctic, with its biota adapted to the unusual combination of a mild climate and a months-long polar day-night cycle, it is at least plausible that during much of the Phanerozoic this currently inhospitable region may have served as the birthplace for important biotic innovations and for major groups that later radiated to lower latitudes. Zinmeister and Feldmann (1984) demonstrated a similar high-latitude heterochroneity for Southern Hemisphere marine faunas during the Cretaceous, and Case (1988, 1989) extended the Weddellian Zoogeographic Province (Fig. 2) to a "biogeographic province" to take account of this for the terrestrial biota. He hypothesised that this province was a centre of diversification for many organisms, and in particular marsupials and species of Nothofagus, during the Late Cretaceous and Cenozoic. ...
Antarctic vegetation is today mostly restricted to non-vascular plants, with a few small angiosperms clinging to the Antarctic Peninsula. However, probably as recently as the mid-Late Pliocene woody angiosperms were present in inland Antarctica, suggesting an overall presence of complex and diverse vegetation. Angiosperms were introduced into Antarctica during the Cretaceous from South America and possibly also Southeast Asia via Australia. These angiosperms speciated rapidly at the prevailing high latitudes and were an important source for the developing angiosperm-dominated vegetation of the Southern Hemisphere. The migration and evolution of early angiosperms in Gondwana was probably facilitated by a high level of disturbance caused primarily by the rifting of the supercontinent. This high-latitude region was an important source of evolutionary novelty during the Late Cretaceous-Paleogene. As the climate deteriorated during the Cenozoic, the angiosperm flora was reduced in biomass and diversity, finally being restricted to the current remnants. The timing and nature of this major regional extinction is still poorly understood.
... The Weddellian Province was proposed as a shallow water and temperate marine shelf region that encompassed New Zealand, Tasmania, Australia, Antarctica and southern South America during the late Cretaceous through Eocene (Zinsmeister 1979, 1982, Woodburne and Zinsmeister 1984, Zinsmeister and Feldmann 1984. At this time, these continents were proximate and shared many marine taxa. ...
... Similarly, nudipleuran evolution is proposed to have taken place around the cooling of Antarctica about 40 or 30 Ma prior to invasion of temperate and tropical seas along northward flowing currents of Antarctic origin (see Göbbeler & Klussmann-Kolb, 2010). Fossil evidence also suggests submergence of shallow-water Antarctic bivalves, gastropods, asteroids, crinoids and decapods into the deep sea during this period (Zinsmeister & Feldmann, 1984). Although the timing remains unclear, molecular evidence indicates that palinurid spiny lobsters originated around Antarctica, invading deep-sea habitats from shallower rocky reefs and then radiating (Tsang et al., 2009). ...
Bathymetric biodiversity patterns of marine benthic invertebrates and demersal fishes have been identified in the extant fauna of the deep continental margins. Depth zonation is widespread and evident through a transition between shelf and slope fauna from the shelf break to 1000 m, and a transition between slope and abyssal fauna from 2000 to 3000 m; these transitions are characterised by high species turnover. A unimodal pattern of diversity with depth peaks between 1000 and 3000 m, despite the relatively low area represented by these depths. Zonation is thought to result from the colonisation of the deep sea by shallow-water organisms following multiple mass extinction events throughout the Phanerozoic. The effects of low temperature and high pressure act across hierarchical levels of biological organisation and appear sufficient to limit the distributions of such shallow-water species. Hydrostatic pressures of bathyal depths have consistently been identified experimentally as the maximum tolerated by shallow-water and upper bathyal benthic invertebrates at in situ temperatures, and adaptation appears required for passage to deeper water in both benthic invertebrates and demersal fishes. Together, this suggests that a hyperbaric and thermal physiological bottleneck at bathyal depths contributes to bathymetric zonation. The peak of the unimodal diversity-depth pattern typically occurs at these depths even though the area represented by these depths is relatively low. Although it is recognised that, over long evolutionary time scales, shallow-water diversity patterns are driven by speciation, little consideration has been given to the potential implications for species distribution patterns with depth. Molecular and morphological evidence indicates that cool bathyal waters are the primary site of adaptive radiation in the deep sea, and we hypothesise that bathymetric variation in speciation rates could drive the unimodal diversity-depth pattern over time. Thermal effects on metabolic-rate-dependent mutation and on generation times have been proposed to drive differences in speciation rates, which result in modern latitudinal biodiversity patterns over time. Clearly, this thermal mechanism alone cannot explain bathymetric patterns since temperature generally decreases with depth. We hypothesise that demonstrated physiological effects of high hydrostatic pressure and low temperature at bathyal depths, acting on shallow-water taxa invading the deep sea, may invoke a stress-evolution mechanism by increasing mutagenic activity in germ cells, by inactivating canalisation during embryonic or larval development, by releasing hidden variation or mutagenic activity, or by activating or releasing transposable elements in larvae or adults. In this scenario, increased variation at a physiological bottleneck at bathyal depths results in elevated speciation rate. Adaptation that increases tolerance to high hydrostatic pressure and low temperature allows colonisation of abyssal depths and reduces the stress-evolution response, consequently returning speciation of deeper taxa to the background rate. Over time this mechanism could contribute to the unimodal diversity-depth pattern.
... (Zinsmeister and Feldmann, 1984). ...
Linuparus White, 1847 comprises three extant species, Linuparus trigonus (Von Siebold, 1824), L. sordidusBruce, 1965, and L. somniosusBerry and George, 1972, as well as 32 fossil species. Most fossil records are from North America and Europe, but the extant species are all confined to the Indo-West Pacific. Different colour forms in L. trigonus and L. sordidus have been noted, with Northern Hemisphere specimens generally darker in colour for both species. The phylogenetic relationships of the extant Linuparus species, including the colour forms, were investigated using mitochondrial 12S rRNA and COI gene sequence analysis. We found no genetic evidence to differentiate the colour morphs of L. sordidus, but the two colour forms of L. trigonus were clearly distinct at the species level. This is supported morphologically by a consistent difference in the shape of the thoracic sternum between the two forms. The paler coloured Southern Hemisphere form is described as a new species, L. meridionalis. Phylogenetic analysis shows that L. trigonus and L. meridionalis sp. nov. are derived sister taxa, while L. somniosus is basal within the genus. Thus the present results support the previous hypothesis that Linuparus was originated in shallow water.
Studies of paleobiogeography have changed markedly in recent decades transforming a once static subject into one which now has great potential as a useful counterpart to systematic and ecological studies in the interpretation of the geological history of organisms. This has resulted, in large part, from the emergence of plate tectonic models which, in turn, have been used as the bases for extremely sophisticated paleoclimatic modeling. As a result, paleobiogeography has attained a level of precision comparable to that of the studies of paleoecology and systematic paleontology. It is now possible to consider causes for global patterns of origin and dispersal of organisms on a much more realistic level than was previously possible.
The james ross basin, situated on the eastern margin of the Antarctic Peninsula, has yielded an extensive fauna of decapod crustaceans spanning Late Cretaceous through Eocene time. To date, 28 species in 22 genera and 18 families have been described (Feldmann, 1992; Feldmann, Tshudy, and Thomson, 1993), making this the most diverse fossil decapod fauna in the Southern Hemisphere. Within the basin, Seymour Island alone contains rocks of the Eocene age La Meseta Formation from which seven species of crabs, one galatheid, and one species of callianassid ghost shrimp have been described (Feldmann and Zinsmeister, 1984; Feldmann and Wilson, 1988; Feldmann, 1992). The fauna of the La Meseta is remarkable also because, although the organisms are preserved in rocks deposited in moderate- to high-energy, shallow-water habitats (Elliot and Trautman, 1982), many of the species represent early occurrences of taxa with living descendants that are characteristic of deeper water, lower latitude habitats (Zinsmeister and Feldmann, 1984).
随着海洋深度的增加，压力逐渐升高而温度逐渐降低。因此，应对压力和温度变化的能力直接影响着海洋动物的垂直分布模式。本文综述了近年来国际上关于压力及温度对海洋动物生理影响的研究进展，概述了3 种常用的研究方法，包括直接比较不同深度近缘海洋动物的差异、使用加压装置培养海洋动物、在常压及原位温度下培养深海动物；然后归纳了压力及温度对海洋动物生理的影响，包括有机渗透调节物质浓度及蛋白质序列、胚胎及幼体发育速率和畸变率、行为模式及代谢速率、基因表达水平；最后讨论了海洋动物适应高压环境的生理机制，压力对海洋动物垂直分布的限制能力，以及浅海动物和深海动物的起源关系。
Issues of scale are becoming increasingly important to paleobiological interpretations of the fossil record. Nevertheless, a number of biological processes display scale-independent behaviors. The effects of predation on the distribution of dense populations of epifaunal, suspension-feeding ophiuroids are scale-independent, at scales ranging from the microecological to the macroevolutionary. On a microecological scale (meters to kilometers, hours to days), dense ophiuroid populations are limited in shallow-water environments by predatory fishes and crabs. On a larger, ecological scale (tens to hundreds of kilometers, decades to centuries), circumstantial evidence indicates that oceanographically driven, multidecadal cycles of predator abundance determine the abundance of ophiuroids throughout the western English Channel. On a macroevolutionary scale (millions to tens of millions of years, global spatial scale), dense, autochthonous assemblages of ophiuroids declined in conjunction with the Mesozoic diversification of modern shell-crushing predators: teleostean fishes, decapod crustaceans, and neoselachian sharks. The sporadic reappearance of dense ophiuroid populations in a late Eocene, shallow marine deposit in Antarctica suggests that predator-prey relationships were disrupted as temperatures declined in the region at that time. Scale-independence is a useful model for explaining and predicting patterns of distribution of dense ophiuroid populations in time and space.
Eight species of brachyuran decapod crustaceans are recorded from coastal outcrops of Island Sandstone between Perpendicular Point and Punakaiki, Westland, New Zealand. The fauna consists of three raninids— Laeviranina pororariensis (Glaessner), L. keyesi n. sp., Lyreidus bennetti n. sp.; two portunids— Rhachiosoma granuliferum (Glaessner), Pororaria eocenica Glaessner; a goneplacid— Carcinoplax temikoensis n. sp.; and two majids— Leptomithrax griffini n. sp., Notomithrax allani n. sp. Together, they form the most diverse brachyuran assemblage yet described from New Zealand. The decapods are preserved in unusual elliptical masses, with their long axes typically parallel to bedding, containing superbly preserved cuticle often surrounded by well-formed fecal pellets, probably of decapod origin. The accumulations are interpreted to be mechanical concentrations within depressions produced by decapods or associated spatangoid echinoids. Although seven of the species have been recorded only from the Island Sandstone, Rhachiosoma granuliferum (Glaessner) is now known to occur in the correlative deep-water facies of the Kaiata Formation in North Westland, as well as in the Tapui Sandstone, North Otago (middle Eocene), and from coeval rocks at Snowdrift Quarry, southeast Otago. The raninids suggest comparison with congeneric forms from Snowdrift Quarry and the Tapui Sandstone, as well as with the La Meseta Formation, Seymour Island, Antarctica. Based upon associated foraminiferans, a Kaiatan–Runangan (late Eocene) age is assigned to this fauna. The occurrences of Carcinoplax, Leptomithrax , and Notomithrax represent paleobiogeographic and stratigraphic records for the genera.
Comprehensive analysis of the Cretaceous and Tertiary decapod crustaceans of the North Pacific Rim, focused primarily on the Brachyura, has resulted in additions to our understanding of the evolution and distribution of these animals, both in that region and globally. Hypotheses about changes in climatological and paleoceanographic conditions have not been extensively tested using decapod crustaceans, although they have been well-documented globally and for the North Pacific Ocean by sedimentological and other faunal evidence. Evidence from the occurrences of decapod crustaceans supports hypotheses obtained through these other means. Because the decapod fauna was studied independent of other faunas, it provides a means by which to compare and test patterns derived from molluscan and other faunal data. The brachyuran decapods show distinctive paleobiogeographic patterns during the Cretaceous and Tertiary, and these patterns are consistent with those documented globally in the molluscan faunas and paleoceanographic modeling. Additionally, the changes in the decapod fauna reflect patterns unique to the North Pacific Ocean. The decapod fauna is primarily comprised of a North Pacific component, a North Polar component, a component of Tethyan derivation, an amphitropical component, and a component derived from the high Southern latitudes. The Cretaceous and Tertiary decapod faunas of the North Pacific Ocean were initially dominated by taxa of North Pacific origin. Decapod diversity was highest in the Pacific Northwest of North America during the Eocene, and diversity has declined steadily since that time. Diversity in Japan was relatively low among the Decapoda until the Miocene, when diversity increased markedly due to the tropical influence of the Tethys and Indo-Pacific region. Diversity has remained high in Japan into the present time. The Cretaceous, Eocene, and Miocene were times of evolutionary bursts within the Brachyura and were separated by periods of evolutionary stasis.
Several very large, taxonomically standardized data sets have been compiled and utilized to investigate biogeographic and evolutionary patterns of continental margin benthic foraminifera. Mean partial species durations for 87 frequently occurring and 180 rarely occurring species on the Atlantic continental margin of North America are the same, namely 21 m.y. The global fossil record of these species indicates no center or centers of origin and indicates very rapid dispersal. The Miocene had the greatest number of first occurrences with 46%, followed by the Pleistocene, Pliocene and Oligocene with approximately 13% each. The remaining 14% first occur in the Eocene, Paleocene, and Cretaceous. Species with a wide geographic distribution often exhibit longer species durations than those with narrow geographic ranges. The vast majority of endemic species (150 of 175) occur rarely and have no fossil record. 1989 The Paleontological Society.
The paleontological exploration of Antartica is constrained by unusual physiographic conditions. For example, the average thickness of the ice cap is 2160 m and only 2.4% of the continent’s rock surface is exposed above the ice at various coastal and mountainous sites (Drewry 1983). Antarctica has also experienced extreme tectonic displacement and accompanying paleoenvironmental change during geologic time. Nevertheless, the existing fossil record indicates that fish have inhabited waters in and around Antarctica at various intervals during the past several hundred million years. These faunas are separated by large gaps in time and are not ancestral to each other. Collectively, however, they indicate that freshwater and marine biotas diversified in the antarctic component of Gondwana at specific intervals during the Paleozoic, Mesozoic and Cenozoic eras.
The early separation of Gondwana and the subsequent isolation of Antarctica caused a long evolutionary history of its fauna. Both, long environmental stability over millions of years and habitat heterogeneity, due to an abundance of sessile suspension feeders on the continental shelf, favoured evolutionary processes of "preadapted" taxa, like for example the Peracarida. This taxon performs brood protection and this might be one of the most important reasons why it is very successful (i.e, abundant and diverse) in most terrestrial and aquatic environments, with some species even occupying deserts. The extinction of many decapod crustaceans in the Cenozoic might have allowed the Peracarida to find and use free ecological niches. Therefore the palaeogeographic, palaeoclimatologic, and palaeo-hydrographic changes since the Palaeocene (at least since about 60 Ma ago) and the evolutionary success of some peracarid taxa (e.g. Amphipoda, Isopoda) led to the evolution of many endemic species in the Antarctic. Based on a phylogenetic analysis of the Antarctic Tanaidacea, Sieg (1988) demonstrated that the tanaid fauna of the Antarctic is mainly represented by phylogenetically younger taxa, and data from other crustacean taxa led Sieg (1988) to conclude that the recent Antarctic crustacean fauna must be comparatively young. His arguments are scrutinized on the basis of more recent data on the phylogeny and biodiversity of crustacean taxa, namely the Ostracoda, Decapoda, Mysidacea, Cumacea, Amphipoda, and Isopoda. This analysis demonstrates that the origin of the Antarctic fauna probably has different roots: an adaptive radiation of descendants from old Gondwanian ancestors was hypothesized for the isopod families Serolidae and Arcturidae, an evolution and radiation of phylogenetically old taxa in Antarctica could also be shown for the Ostracoda and the amphipod family Iphimediidae. A recolonization via the Scotia Are appears possible for some species, though it is not very likely (some Isopoda, like the Sphaeromatidea, are widely distributed in the Subantarctic, but rare in the high Antarctic). However, it could also be that the species of this family and others were not able to survive when the ice reached the sublittoral shelf in the high Antarctic during glacial periods.
Crinoids are reported from the New Zealand Paleocene for the first time and include rare articulated columnals and brachia with pinnules. The presence of isocrinids in the Kauru Formation and younger Palaeogene strata reveals that the supposed shift of some isocrinids from a shallower to a deeper environment actually occurred much later in the Paleogene, and not the Late Cretaceous as previously supposed. Associated molluscs indicate a mid to upper "Wangaloan' Stage (local), equivalent to mid Paleocene. A summary of the New Zealand crinoid fossil record is presented. -Authors
Articulate brachiopods from the Aptian–Coniacian (Kotick Point and Whisky Bay Formations, Gustav Group) and the Santonian–Campanian (Santa Marta Formation, Marambio Group) of James Ross Island are described. A new terebratulid species, Rectithyris whiskyi n. sp., is described from the late Albian–early Coniacian of the Whisky Bay Formation. The record from the late Albian is supported by palynological evidence making it contemporaneous with other species of Rectithyris from Europe. The relative abundance of Rectithyris whiskyi n. sp. in late Turonian to early Coniacian sections indicates an extended biohorizon that may aid biostratigraphic correlation in the James Ross Island region.
The brachiopods have some affinities with faunas described from Europe, northern Siberia, North America, Madagascar, southern India, Western Australia, and Alexander Island, Antarctic Peninsula. Elements of the James Ross Island brachiopod fauna probably migrated by the following routes: 1) from northern high latitudes via the Eastern Pacific; 2) from Europe via the north and central Atlantic and opening south Atlantic Ocean; and 3) via Eastern Tethys, the East African Seaway, to the south Atlantic Ocean. Brachiopod evidence supports a fully marine connection between the central Atlantic and south Atlantic Ocean (Route 2) possibly as early as the late Albian (as do ammonite faunas from western Africa), and certainly by the late Turonian. Route 3 was established in the Cretaceous by the Aptian?–Albian to eastern Africa and Madagascar and to the Antarctic Peninsula by the late Turonian. Faunal links between James Ross Island and Western Australia support the Late Cretaceous juxtaposition of these plates.
A distinct austral brachiopod fauna may be present in the Cretaceous from the Aptian onwards (although current evidence is scant). Antarctic Peninsular and Western Australian faunas yield five brachiopod genera (and their species) endemic to Gondwanaland's southern marine fauna. Other genera known from the Antarctic Peninsula ( Kingena, Ptilorhynchia , and Rectithyris ) and the Northern Hemisphere may have species endemic to Gondwanaland.
The new subfamily Struthiopterinae is proposed for the aporrhaid gastropods occurring in the Late Cretaceous-early Tertiary Weddellian Province along the southern margin of the Pacific. The following genera are placed within the Struthiopterinae: Struthioptera Finlay and Marwick, 1937; Austroaporrhais n. gen.; and Struthiochenopus n. gen. The temporal and biogeographic distribution of members of Struthiopterinae show a similar pattern to other Southern Hemisphere groups of Late Cretaceous and early Cenozoic molluscs with initial disappearance from the western Australasia of the Weddellian Province by the Paleocene while surviving in Antarctica until the late Eocene and eventually disappearing in southern South America during the early Miocene.
Also included in this paper is a reappraisal of the species assignable to these genera from Late Cretaceous and early Tertiary of New Zealand, Antarctica, and southern South America together with the description of five new species. The following new species of the Struthiopterinae are described: Austroaporrhais larseni n. sp., A. stilwelli n. sp., A. dorotensis n. sp., Struthiochenopus antarcticus n. sp., and S. philippii n. sp.
One of the most important breakthroughs in Antarctic geological research over the last three decades has been the elucidation of the continent’s fossil record. Although fossils have been known since the very earliest days of scientific exploration in the south polar regions, it is only comparatively recently that their study has been placed within a firm scientific framework. Detailed taxonomic studies of many key groups have been completed and it is now possible, for the first time, to take a broad perspective of the history of life on our southernmost continent. A surprising diversity of fossil plants and animals has now been found in Antarctica; the story they tell is every bit as important to the development of our understanding of the broad patterns of the history of life on Earth as that from other continents.
The traditional focus of paleobiogeographic study has been the province, a statistical entity defined by clusters of range endpoints of invididual taxa. The study of such provinces has been useful in inferring past continental positions (although ambiguities remain that must be resolved using independent geological criteria) and in understanding the role of past global geographies in regulating biotic diversity through changes in the numbers and extent of provinces. This approach can be complemented by the treatment of geographic ranges of taxa as irreducible or emergent traits with far-reaching evolutionary effects upward and downward within a genealogical hierarchy. Temperature tolerances in benthic marine organisms appear to be by-products of selection for enzyme structures imparting favorable activity levels within the normal temperature range rather than direct products of selection for resistance to temperature extremes. Thus, geographic range endpoints, which are also influenced by dispersal capability and the resulting scale of gene flow among disjunct populations, are not direct products of selection. However, the magnitudes of geographic range of species and clades behave as emergent properties and significantly influence taxonomic survivorship during background and mass extinctions in ways that are not extrapolations of effects at lower hierarchical levels. Biogeography shapes macroevolutionary patterns of origination and extinction during times of normal, background extinction and mass extinction. Preferential extinction among regions or among endemic rather than widespread clades can result in strong biases in the nature of the survivors of mass extinctions, with taxa being lost not because of selection against attributes of individual organisms but because of higher-order patterns of geographic selectivity.-from Authors
The marine faunas from Patagonia, which are in need of a comprehensive revision, are particularly important in the understanding of the origin and evolution of the marine biota in the southern hemisphere during the final breakup of Gondwanaland during the Late Cretaceous-early Tertiary. The Eocene Rio Turbio Formation in southern Patagonia (Argentina) contains a unique fauna of marine mollusks. This paper describes 35 species of bivalves from that unit. Nine of them are new: Nucula (Leionucula) guillermensis, Yoldia (Calorhadia) patagonica, Atrina rioturbiensis, Electroma patagonica, Venericardia (Venericor) carrerensis, Crassatella brandmayri, Solena (Eosolen) hunickeni, Pholadidea frenguellii, and Periploma (Aelga) primaverensis. In addition, 26 other species are also described, though their exact systematic relationships cannot at present be accuracely established. -Author
Rocks of the Rio Turbio Formation, exposed in southern Patagonia, Argentina, represent one of very few occurrences of Eocene rocks in the region. Decapod crustaceans collected from the unit include one species of thalassinidean mud shrimp; Turbiocheir minutospinata, new genus, new species; and three species of brachyurans; Raninoides rioturbiensis, new species; Megokkos patagoniensis, new species; and Nitotacarcinus antipodes, new species. The three brachyuran genera are also known from species in the Northeast Pacific, suggesting an amphitropical distributional pattern.
The biogeography and ecology of decapod crustaceans was described for the higher latitudes of the Southern Ocean. The analyzed area included the transitional or antiboreal region of the South American continental shelves (south of about 42°30'S), the Antarctic continental shelves, the Subantarctic islands of the Scotia and the Kerguelen Arcs, the deep sea south of about 42°S and the pelagic realm between the Subtropical Convergence and the Antarctic continent. A broad base of own data and a review of the literature revealed the presence of 98 benthic decapod species in the entire area, with 92 species on the continental shelves and around the Subantarctic islands, and 6 species in the deep sea. A total of 34 decapod species live in the pelagic system south of the Subtropical Convergence. About 50% of the benthic species, nearly all deep-sea species, but only one pelagic decapod are endemic in the analyzed sectors of the Southern Ocean. Eualus kinzeri (Caridea: Hippolytidae) is the only endemic decapod of the Antarctic continental shelves. By means of a multivariate cluster analysis the antiboreal decapod fauna of South America was separated from the species living around Antarctica and the Subantarctic islands of the Scotia and Kerguelen Arc. In contrast to earlier studies the northern distribution limit of the Antarctic decapod fauna was set at approximately 55°30'S, and includes species which are distributed on the southern tip of South America. The species number in the antiboreal region of South America is 79, and higher than known before. The caridean shrimps are the most numerous group within the entire area, and together with the anomuran crabs, the palinuran and astacuran lobsters they demonstrate a high degree of eurybathy compared to the Brachyura. The restriction of the Brachyura to shallow-water zones is discussed as one reason, that caused the absence of this group on the Antarctic continental shelves after the successive elimination of the shallow-water fauna during glaciation of the southern hemisphere.
On the basis of recent collections from the Upper Eocene La Meseta Formation of Seymour Island, Antartic Peninsula, the morphology, systematic position, taphonomy, and paleoecology of the isocrinid Metacrinus fossilis are investigated. A new species, Notocrinus rasmusseni, is described as the first comatulid crinoid known from the Antarctic fossil record. About 10% of M. fossilis individuals show brachial regeneration, in contrast to regeneration frequencies of 70-90% among modern Japanese isocrinids. The anomalous occurrence of isocrinids in shallow-water facies of the La Meseta is attributed to a combination of reduced predation pressure, the presumed stalkless mode of life, and a favorable temperature regime in Antarctic surface waters prior to the onset of cooling at the close of the Eocene. -from Authors
Temperature can influence the physiology of marine organisms on a variety of time scales ranging from short-term fluctuations (tidal, vertical migration) to long-term climatic change. During the past 60 Ma shallow water marine organisms living at high southern latitudes around the margins of the continental fragments of Gondwana have experienced a decrease in mean seawater temperature from about 15°C in the early Tertiary to the present range of roughly + 2° to − 1.8°C. The early Cretaceous fauna around Gondwana was relatively rich and diverse. Despite the influence of glaciation the present fauna is rich in biomass and can show a very high within-site diversity. Some groups, however, notably fish and groups with calcareous skeletons such as bivalves and gastropods, are low in species richness. Evidence from physiology suggests that adaptation to low temperature is not a particularly severe evolutionary problem. The concept that the tropics are more equable than the polar regions is purely anthropocentric and entirely inappropriate for marine organisms. Polar organisms generally have a low cost of maintenance allowing higher growth efficiencies and thus affording a distinct energetic advantage over warmer water forms. Relating periods of extinction to a lowering of seawater temperature leads to a paradox in that the rates of cooling are so much slower (by several orders of magnitude) than those with which living marine organisms can cope, that it is difficult to see why previous marine communities could not adapt to track the change in temperature. One explanation is that altough a long-term change in mean temperature is often slow, this may be accompanied by severe short-term changes with which the fauna cannot cope. Also, it is unlikely that temperature change alone causes widespread extinction, but temperature varying with other ecological factors. If temperature change is indeed a problem then the direction is immaterial, climatic ‘amelioration’ is just as much a problem as climatic ‘deterioration’. Clearly physiology, ecology and palaeontology have much to teach each other.
A 300-m sequence of well-exposed fossiliferous outcrops in bluffs along the Colville River, northern Aslaska, has yielded diverse, well-preserved Maastrichtian and Danian ostracode assemblages. The Maastrichtian strata are nonmarine flood-plain deposits and contain diverse terrestrial and aquatic fossils. The Danian strata are predominantly marginal-marine and shallow-marine and include an abundant and diverse invertebrate fauna. During the Maastrichtian and early Palaeocene, polar terrestrial and marine assemblages consisted predominantly of endemic organisms that were adapted to the cool temperatures, seasonal low light conditions, and geographic isolation characteristic of northern high-latitude environments. -from Authors
The Eocene La Meseta Formation on Seymour Island, Antarctica, contains a diverse and abundant invertebrate and vertebrate fauna and, as such, is of key paleontological importance. Associated with this marine fauna is abundant angiosperm and conifer fossil wood, which commonly contains Teredolites borings. These borings are either infilled by clastic sediment, forming geopetal structures, or by calcite cements. The cements usually comprise two generations of radial-fibrous high-Mg calcite, post-dated by equant sparry calcite. The radial-fibrous cement is largely non-luminescent, non-ferroan calcite. However, within individual generations of radial-fibrous calcite there is a transition from non-ferroan non-luminescent to ferroan, orange-luminescent calcite at the margins of the fringing cement. These radial-fibrous cements have δ 13C values of 1.72 to -42.59‰, and Mg (ppm) values of between 18360 and 26735. On the basis of cement-fabric, stable isotope, and trace element data, these cements are interpreted as having precipitated from marine pore waters with total dissolved carbon derived from both methane oxidation and an inorganic marine carbon source. As HMC cements are diagenetically unstable, the preservation of these cements is remarkable, and must reflect very limited post sea-floor diagenesis. In addition, the cement oxygen isotope data are consistent with previous results for molluscs from the La Meseta Formation. These wood cements retain a primary environmental geochemical signature, with precipitation from cold marine pore waters at or near the sediment-water interface. A cool-to cool-temerature climate is inducated for the lower late early to early middle Eocene part of the La Meseta Formation. These data support the view that Antarctic climates deteriorated significantly by late early to early middle Eocene times.
Ecology, the biological science of environment, has not produced a synthesis of environment from its broad technical knowledge of influence of external parameters on organisms. Before Darwin (1859), environment was considered an organic whole. Everything in it made some contribution and has some meaning with respect to everything else. Darwin subscribed to this view, but his emphasis, and that of his followers, on the evolving organism struggling to survive, suppressed the exploration of holistic aspects of the origin of species that might have been developed. After Darwin, the organism came into great focus, first as a comparative anatomical entity, then later with physiological, cellular, molecular, behavioural, and genetic detail. In contrast, the organism’s environment blurred through relative inattention into a fuzzy generality. The result was two distinct things (dualism), organism and environment, supplanting the original unified organism—environment whole (synergism). (Patten, 1982).
Ce mémoire est une synthèse de mes travaux de recherche réalisés au cours des onze années
écoulées depuis la soutenance de ma thèse de doctorat. Il présente mes thématiques de recherche,
les principaux résultats obtenus et constitue aussi une prospective pour la réalisation de mes projets
futurs. Mes recherches portent sur l'analyse macroévolutive et macroécologique de la diversité
fossile et actuelle des échinides. Ce groupe constitue un modèle d'étude de la biodiversité marine
que j'aborde à différentes échelles taxinomiques et géographiques, ainsi qu'à travers des contextes
variés, de la diversification des échinides irréguliers au Jurassique aux espèces abyssales et
antarctiques actuelles. Mes thématiques de recherche s'articulent autour de l'étude des dimensions
phylogénétiques, morphologiques, écologiques et biogéographiques de la diversité des échinides.
Après une brève introduction, le premier chapitre du mémoire présente les spécificités du modèle
d'étude, le choix des données traitées et les problématiques analytiques associées. Mes thématiques
de recherche sont ensuite abordées dans trois chapitres consacrés à (1) l'étude de la structuration
phylogénétique, (2) la caractérisation de la disparité morphologique et (3) l'analyse
biogéographique et macroécologique de faunes d'échinides. En guise de conclusion, le dernier
chapitre reprend mes principaux projets de recherche et les résume en soulignant la
complémentarité des thématiques abordées.
Much of the argument about the existence or nonexistence of centres of origin has been focused on the marine East Indies. During the past 10 years, considerable new information has become available. Patterns suggesting historic dispersals from the East Indies have been described. It is now apparent that there is, in several animal groups, an increasing trend in average generic age from the East Indies outward. Paleontological studies have revealed significant onshore to offshore evolutionary trends during much of the Phanerozoic. Antitropical and other disjunct patterns in the Indo-West Pacific suggest that the extinction process often begins in the East Indies and spreads outward. Widespread Indo-West Pacific species, that possibly originated in the East Indies, occasionally surmount biogeographic barriers to colonize adjacent regions. The biogeographic patterns described are compatible with, and provide support for, the centre of origin hypothesis. Successful evolution, which results in the formation of new phyletic lines, takes place in the nearshore waters of centres of origin. From such centres, new species, which may eventually give rise to new higher taxa, spread out both vertically and horizontally. As they spread vertically, they replace older forms from the mid- and outer shelf and eventually from the slope. As they spread horizontally, they replace their more generalized, peripheral relatives, leaving as evidence the historic dispersal and age patterns which have been noted.
Throughout the late Mesozoic a distinctive bivalve fauna can be traced
around the southern Gondwana margins. It is characterized by inoceramids
(Retroceramus, Inoceramus, Anopaea), oxytomids (Malayomaorica, Arctotis,
Aucellina, Maccoyella), and buchiids (Jeletzkiella, Australo buchia?),
together with certain other types such as monotids and trigoniids.
Throughout much of this period the fauna appears to have been centered
on a core region which stretched approximately between southern
Patagonia and Indonesia. However, it expanded in the Tithonian to
include the Himalayas, and at the Jurassic-Cretaceous boundary, clear
transitions to more diverse faunas can be detected in both southern
South America and the India-East Africa region. The presence of a
distinct austral bivalve fauna suggests that there may well have been
some form of climatic zonation at high latitudes in the southern
hemisphere. Support for this claim comes from the phenomenon of
bipolarity which is well defined in several Late Jurassic and Early
Cretaceous genera. The existence of an abundant late Mesozoic bivalve
fauna in Antarctica further underlines the importance of polar regions
as potential evolutionary and dispersal centers.
Majungaella is a survivor genus of a long lineage of the family Progonocytheridae, ranging from the Jurassic to the Pliocene. In this paper new species from Argentina and Brazil are described and appropriately illustrated, comprising a systematic review of 16 species, including two new ones. The Jurassic and Early Cretaceous species seem to have inhabited mainly shallow, warm waters, whereas from the mid-Late Cretaceous and especially in the Cenozoic, a retrothermal propensity is observed in the genus. The records of Majungaella are revised and its distribution is used to demonstrate the prior juxtaposition of subsequently separated Gondwana continental blocks and the opening of new seaways. The data have allowed a deeper understanding of the depositional sequences and supplied information on the early geological history and subsequent palaeoceanographic evolution of the South Atlantic Ocean. The affinities of the ostracod faunas from South America and other gondwanan localities are used to analyze the evolution of seaways and oceanic barriers.
Three Antarctic Ocean K/T boundary sequences from ODP Site 738C on the Kerguelen Plateau, ODP Site, 752B on Broken Ridge and ODP Site 690C on Maud Rise, Weddell Sea, have been analyzed for stratigraphic completeness and faunal turnover based on quantitative planktic foraminiferal studies. Results show that Site 738C, which has a laminated clay layer spanning the K/T boundary, is biostratigraphically complete with the earliest Tertiary Zones P0 and P1a present, but with short intrazonal hiatuses. Site 752B may be biostratigraphically complete and Site 690C has a hiatus at the K/T boundary with Zones P0 and P1a missing.
Environmental change is the norm and it is likely that, particularly on the geological timescale, the temperature regime experienced by marine organisms has never been stable. These temperature changes vary in timescale from daily, through seasonal variations, to long-term environmental change over tens of millions of years. Whereas physiological work can give information on how individual organisms may react phenotypically to short-term change, the way benthic communities react to long-term change can only be studied from the fossil record. The present benthic marine fauna of the Southern Ocean is rich and diverse, consisting of a mixture of taxa with differing evolutionary histories and biogeographical affinities, suggesting that at no time in the Cenozoic did continental ice sheets extend sufficiently to eradicate all shallow-water faunas around Antarctica at the same time. Nevertheless, certain features do suggest the operation of vicariant processes, and climatic cycles affecting distributional ranges and ice-sheet extension may both have enhanced speciation processes. The overall cooling of southern high-latitude seas since the mid-Eocene has been neither smooth nor steady. Intermittent periods of global warming and the influence of Milankovitch cyclicity is likely to have led to regular pulses of migration in and out of Antarctica. The resultant diversity pump may explain in part the high species richness of some marine taxa in the Southern Ocean. It is difficult to suggest how the existing fauna will react to present global warming. Although it is certain the fauna will change, as all faunas have done throughout evolutionary time, we cannot predict with confidence how it will do so.
Magnetostratigraphic correlation of the Eureka Sound Formation in the Canadian high Arctic reveals profound difference between the time of appearance of fossil land plants and vertebrates in the Arctic and in mid-northern latitudes. Latest Cretaceous plant fossils in the Arctic predate mid-latitude occurrences by as much as 18 million years, while typical Eocene vertebrate fossils appear some 2 to 4 million years early.
The Lower Pennsylvanian Hale Formation, which comprises the lower portion of the type Morrowan Series, in northwestern Arkansas, is subdivided into the Cane Hill and overlying Prairie Grove Members. The Cane Hill Member includes interbedded shale and sandstone with a basal conglomerate containing clasts reworked from underlying, truncated Mississippian formations. The Prairie Grove Member is highly variable, but includes sandy biosparite and calcareous sandstone. Highly fossiliferous pebble conglomerate and calcirudite lenses occur sporadically throughout the Hale Formation. Ammonoids and conodonts show that the Cane Hill-Prairie Grove boundary is unconformable.
Several thousand ammonoids collected from more than 100 localities in the Hale Formation show that four ammonoid zones and two subzones are recognizable in the Hale succession, and consequently in the redefined Halian Stage of the Morrowan Series. These are, in ascending order, the Retites semiretia, Quinnites henbesti, Arkanites relictus (including the Arkanites relictus relictus and overlying Cancelloceras huntsvillense Subzones) and Verneuilites pygmaeus Zones. Halian Stage ammonoids are known primarily from northern Arkansas, but an upper Arkanites relictus Zone ( Cancelloceras huntsvillense Subzone) ammonoid assemblage occurs in the Primrose Member of the Golf Course Formation in south central Oklahoma.
Conodont-ammonoid associations in the Hale sequence provide a basis for integration of independently based zonal information. Rhachistognathus primus Zone conodonts occur in the Retites semiretia Zone; the Idiognathoides sinuatus Zone ranges through the Quinnites henbesti and Arkanites relictus relictus Subzone. The overlying Cancelloceras huntsvillense Subzone and Verneuilites pygmaeus Zone both contain conodonts of the Neognathodus symmetricus Zone.
The Hale ammonoid succession has few, if any, species in common with the type Namurian of Europe, but numerous genera are common to both sequences and the generic successions coincide and are equivalent in degree of development. The Retites semiretia Zone is equivalent to the Reticuloceras circumplicatile Zone (R 1 a); the Quinnites henbesti and lower Arkanites relictus Zones correspond to some portion of the R 2 b–R 2 c interval; and the upper Arkanites relictus Zone and the Verneuilites pygmaeus Zone correlate to Zone G 1 . The Retites semiretia Zone correlates to the lower Reticuloceras-Baschkortoceras Genozone (Nm 2 b 1 ) of the upper Namurian in the south Urals; the Quinnites henbesti Zone is equivalent to some portion of the Nm 2 b 2–3 intervals of this zone; the lower Arkanites relictus Zone is equivalent to the lower Bilinguites-Cancelloceras Genozone (Nm 2 c 1 ) and the upper Arkanites relictus and Verneuilites pygmaeus Zones correspond to the uppermost interval (Nm 2 c 2 ) in the south Urals sequence.
Systematic descriptions of biostratigraphically significant Halian taxa, including Reticuloceras tiro Gordon, R. wainwrighti Quinn, Retites semiretia McCaleb, Arkanites relictus relictus (Quinn, McCaleb, and Webb), A. relictus redivivus n.subsp., Quinnites n.gen. (type species Q. henbesti (Gordon)), Q. textum (Gordon), Bilinguites eliasi n.sp., Cancelloceras huntsvillense n.sp., and Verneuilites pygmaeus (Mather) are also presented.
An oxygen and carbon isotopic history based on analyses of ben- thonic and planktonic foraminifera in three overlapping subantarc- tic sections is presented for the last 55 m.y. with a sampling interval ofless than 1 m.y. Surface temperature at Site 277, on the Campbell Plateau, was about 19°C in the early Eocene, about 13°C in the mid- dle Eocene, about 11°C in the late Eocene, and about 7°C in the Oligocene. Declines in temperature appear to have been rather rapid and are separated by episodes of relative temperature stability. Bot- tom temperature at Site 277 was about 1°C below surface temperature in the Paleocene and about 2°C below surface temperature in the Oligocene. Site 279, on the Macquarie Ridge, records an early Miocene warming of over 2°C followed by a cooling and a second similar temperature rise in the middle Miocene. Bottom temperature at this somewhat deeper site was about 3°C below surface temperature and was probably as low as 4°C during part of the early Miocene. Com- parisons between Sites 277 and 279 suggest that from the early Oligo- cene temperatures of deep water were low like the present day, im- plying that the mean annual temperature in high southern latitudes was near freezing by the beginning of the Oligocene (but certainly no earlier). From this time glaciers would have descended to sea level, and there would have been sea-ice production. If an ice sheet were present, it could not have been more than a small fraction of its present-day size. Site 281, on the South Tasman Rise, extends the record into the middle and late Miocene during which time the major East Antarctic ice sheet accumulated. A significant rise in surface temperature dur- ing the late Miocene did not cause the melting of this ice sheet, demonstrating that by this time it had already achieved its present in- vulnerability to climatic change. Since temperatures during much of the Miocene were significantly above any Pleistocene values, it is ex- tremely unlikely that any climatic change in the geologically near future will significantly affect the stability of the East Antarctic ice sheet.
A fossil land mammal, apparently the first found in Antarctica, belongs to the extinct marsupial family Polydolopidae. The fossils were recovered from rocks about 40 million years old on Seymour Island, in the northern Antarctic Peninsula. The newly discovered marsupials support theories that predicted their former presence in Antarctica and strengthen proposals that Australian marsupials perhaps originated from South American species that dispersed across Antarctica when Australia still was attached to it, prior to 56 million years ago.