1
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Foffa D, Young MT, Brusatte SL. Comparative functional morphology indicates niche partitioning among sympatric marine reptiles. ROYAL SOCIETY OPEN SCIENCE 2024; 11:231951. [PMID: 39076819 PMCID: PMC11285779 DOI: 10.1098/rsos.231951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/17/2023] [Revised: 03/15/2024] [Accepted: 03/19/2024] [Indexed: 07/31/2024]
Abstract
Mesozoic marine ecosystems were dominated by diverse lineages of aquatic tetrapods. For over 50 Ma in the Jurassic until the Early Cretaceous, plesiosaurians, ichthyosaurians and thalattosuchian crocodylomorphs coexisted at the top levels of trophic food webs. We created a functional dataset of continuous craniomandibular and dental characters known from neontological studies to be functionally significant in modern aquatic tetrapods. We analysed this dataset with multivariate ordination and inferential statistics to assess functional similarities and differences in the marine reptile faunas of two well-sampled Jurassic ecosystems deposited in the same seaway: the Oxford Clay Formation (OCF, Callovian-early Oxfordian, Middle-Late Jurassic) and the Kimmeridge Clay Formation (KCF, Kimmeridgian-Tithonian, Late Jurassic) of the UK. Lower jaw-based macroevolutionary trends are similar to those of tooth-based diversity studies. Closely related species cluster together, with minimal overlaps in the morphospace. Marine reptile lineages were characterized by the distinctive combinations of features, but we reveal multiple instances of morphofunctional convergence among different groups. We quantitatively corroborate previous observations that the ecosystems in the OCF and KCF were markedly distinct in faunal composition and structure. Morphofunctional differentiation may have enabled specialization and was an important factor facilitating the coexistence of diverse marine reptile assemblages in deep time.
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Affiliation(s)
- Davide Foffa
- Department of Geosciences, Virginia Tech, Blacksburg, VA, USA
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, UK
- Department of Natural Sciences, National Museums Scotland, Edinburgh, UK
| | - Mark T. Young
- School of GeoSciences, Grant Institute, University of Edinburgh, EdinburghEH9 3FE, UK
| | - Stephen L. Brusatte
- Department of Natural Sciences, National Museums Scotland, Edinburgh, UK
- School of GeoSciences, Grant Institute, University of Edinburgh, EdinburghEH9 3FE, UK
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2
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Lomax DR, de la Salle P, Perillo M, Reynolds J, Reynolds R, Waldron JF. The last giants: New evidence for giant Late Triassic (Rhaetian) ichthyosaurs from the UK. PLoS One 2024; 19:e0300289. [PMID: 38630678 PMCID: PMC11023487 DOI: 10.1371/journal.pone.0300289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2023] [Accepted: 02/24/2024] [Indexed: 04/19/2024] Open
Abstract
Giant ichthyosaurs with body length estimates exceeding 20 m were present in the latest Triassic of the UK. Here we report on the discovery of a second surangular from the lower jaw of a giant ichthyosaur from Somerset, UK. The new find is comparable in size and morphology to a specimen from Lilstock, Somerset, described in 2018, but it is more complete and better preserved. Both finds are from the uppermost Triassic Westbury Mudstone Formation (Rhaetian), but the new specimen comes from Blue Anchor, approximately 10 km west along the coast from Lilstock. The more complete surangular would have been >2 m long, from an individual with a body length estimated at ~25 m. The identification of two specimens with the same unique morphology and from the same geologic age and geographic location warrants the erection of a new genus and species, Ichthyotitan severnensis gen. et sp. nov. Thin sections of the new specimen revealed the same histological features already observed in similar giant ichthyosaurian specimens. Our data also supports the previous suggestion of an atypical osteogenesis in the lower jaws of giant ichthyosaurs. The geological age and giant size of the specimens suggest shastasaurid affinities, but the material is too incomplete for a definitive referral. Ichthyotitan severnensis gen. et sp. nov., is the first-named giant ichthyosaur from the Rhaetian and probably represents the largest marine reptile formally described.
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Affiliation(s)
- Dean R. Lomax
- Palaeobiology Research Group, School of Earth Sciences, University of Bristol, Bristol, United Kingdom
- Department of Earth and Environmental Sciences, The University of Manchester, Manchester, United Kingdom
| | - Paul de la Salle
- The Etches Collection – Museum of Jurassic Marine Life, Dorset, United Kingdom
| | - Marcello Perillo
- Paleontology division, Institute of Geosciences, University of Bonn, Bonn, Germany
| | | | | | - James F. Waldron
- Dinosaurs Will Always Be Awesome, DWABA Museum, Orlando, Florida, United States of America
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3
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Weppe R, Condamine FL, Guinot G, Maugoust J, Orliac MJ. Drivers of the artiodactyl turnover in insular western Europe at the Eocene-Oligocene Transition. Proc Natl Acad Sci U S A 2023; 120:e2309945120. [PMID: 38109543 PMCID: PMC10756263 DOI: 10.1073/pnas.2309945120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Accepted: 11/10/2023] [Indexed: 12/20/2023] Open
Abstract
Simultaneously investigating the effects of abiotic and biotic factors on diversity dynamics is essential to understand the evolutionary history of clades. The Grande Coupure corresponds to a major faunal turnover at the Eocene-Oligocene transition (EOT) (~34.1 to 33.55 Mya) and is defined in western Europe as an extinction of insular European mammals coupled with the arrival of crown clades from Asia. Here, we focused on the species-rich group of endemic European artiodactyls to determine the drivers of the Grande Coupure during the major environmental disruptions at the EOT. Using Bayesian birth-death models, we analyzed an original high-resolution fossil dataset (90 species, >2,100 occurrences) from southwestern France (Quercy area) and estimated the regional diversification and diversity dynamics of endemic and immigrant artiodactyls. We show that the endemic artiodactyl radiation was mainly related to the Eocene tropical conditions, combined with biotic controls on speciation and clade-related diversity dependence. We further highlight that the major environmental changes at the transition (77% of species became extinct) and the concurrent increase in seasonality in Europe during the Oligocene were likely the main drivers of their decline. Surprisingly, our results do not support the widely-held hypothesis of active competition between endemic and immigrant artiodactyls but rather suggest a passive or opportunistic replacement by immigrants, which is further supported by morphological clustering of specific ecological traits across the Eocene-Oligocene transition. Our analyses provide insights into the evolutionary and ecological processes driving the diversification and decline of mammalian clades during a major biological and climatic crisis.
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Affiliation(s)
- Romain Weppe
- Institut des Sciences de l’Evolution de Montpellier, Univ Montpellier, CNRS, IRD, Montpellier Cedex 534095, France
| | - Fabien L. Condamine
- Institut des Sciences de l’Evolution de Montpellier, Univ Montpellier, CNRS, IRD, Montpellier Cedex 534095, France
| | - Guillaume Guinot
- Institut des Sciences de l’Evolution de Montpellier, Univ Montpellier, CNRS, IRD, Montpellier Cedex 534095, France
| | - Jacob Maugoust
- Institut des Sciences de l’Evolution de Montpellier, Univ Montpellier, CNRS, IRD, Montpellier Cedex 534095, France
| | - Maëva J. Orliac
- Institut des Sciences de l’Evolution de Montpellier, Univ Montpellier, CNRS, IRD, Montpellier Cedex 534095, France
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4
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Cribb AT, Formoso KK, Woolley CH, Beech J, Brophy S, Byrne P, Cassady VC, Godbold AL, Larina E, Maxeiner PP, Wu YH, Corsetti FA, Bottjer DJ. Contrasting terrestrial and marine ecospace dynamics after the end-Triassic mass extinction event. Proc Biol Sci 2023; 290:20232232. [PMID: 38052241 DOI: 10.1098/rspb.2023.2232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Accepted: 11/14/2023] [Indexed: 12/07/2023] Open
Abstract
Mass extinctions have fundamentally altered the structure of the biosphere throughout Earth's history. The ecological severity of mass extinctions is well studied in marine ecosystems by categorizing marine taxa into functional groups based on 'ecospace' approaches, but the ecological response of terrestrial ecosystems to mass extinctions is less well understood due to the lack of a comparable methodology. Here, we present a new terrestrial ecospace framework that categorizes fauna into functional groups as defined by tiering, motility and feeding traits. We applied the new terrestrial and traditional marine ecospace analyses to data from the Paleobiology Database across the end-Triassic mass extinction-a time of catastrophic global warming-to compare changes between the marine and terrestrial biospheres. We found that terrestrial functional groups experienced higher extinction severity, that taxonomic and functional richness are more tightly coupled in the terrestrial, and that the terrestrial realm continued to experience high ecological dissimilarity in the wake of the extinction. Although signals of extinction severity and ecological turnover are sensitive to the quality of the terrestrial fossil record, our findings suggest greater ecological pressure from the end-Triassic mass extinction on terrestrial ecosystems than marine ecosystems, contributing to more prolonged terrestrial ecological flux.
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Affiliation(s)
- Alison T Cribb
- Department of Earth Sciences, University of Southern California, Los Angeles, CA, USA
- School of Ocean and Earth Science, University of Southampton, Southampton, UK
| | - Kiersten K Formoso
- Department of Earth Sciences, University of Southern California, Los Angeles, CA, USA
- The Dinosaur Institute, Natural History Museum of Los Angeles County, Los Angeles, CA, USA
| | - C Henrik Woolley
- Department of Earth Sciences, University of Southern California, Los Angeles, CA, USA
- The Dinosaur Institute, Natural History Museum of Los Angeles County, Los Angeles, CA, USA
| | - James Beech
- Department of Earth Sciences, University of Southern California, Los Angeles, CA, USA
| | - Shannon Brophy
- Department of Earth Sciences, University of Southern California, Los Angeles, CA, USA
| | - Paul Byrne
- Department of Earth Sciences, University of Southern California, Los Angeles, CA, USA
- The Dinosaur Institute, Natural History Museum of Los Angeles County, Los Angeles, CA, USA
| | - Victoria C Cassady
- Department of Earth Sciences, University of Southern California, Los Angeles, CA, USA
| | - Amanda L Godbold
- Department of Earth Sciences, University of Southern California, Los Angeles, CA, USA
| | - Ekaterina Larina
- Department of Earth Sciences, University of Southern California, Los Angeles, CA, USA
- Department of Geological Sciences, Jackson School of Geosciences, University of Texas at Austin, Austin, TX, USA
| | - Philip-Peter Maxeiner
- Department of Earth Sciences, University of Southern California, Los Angeles, CA, USA
| | - Yun-Hsin Wu
- Department of Earth Sciences, University of Southern California, Los Angeles, CA, USA
- The Dinosaur Institute, Natural History Museum of Los Angeles County, Los Angeles, CA, USA
| | - Frank A Corsetti
- Department of Earth Sciences, University of Southern California, Los Angeles, CA, USA
| | - David J Bottjer
- Department of Earth Sciences, University of Southern California, Los Angeles, CA, USA
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Voje KL, Saulsbury JG, Starrfelt J, Latorre DV, Rojas A, Kinneberg VB, Liow LH, Wilson CJ, Saupe EE, Grabowski M. Measurement theory and paleobiology. Trends Ecol Evol 2023; 38:1165-1176. [PMID: 37696719 DOI: 10.1016/j.tree.2023.08.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 08/07/2023] [Accepted: 08/08/2023] [Indexed: 09/13/2023]
Abstract
Measurement theory, a branch of applied mathematics, offers guiding principles for extracting meaning from empirical observations and is applicable to any science involving measurements. Measurement theory is highly relevant in paleobiology because statistical approaches assuming ratio-scaled variables are commonly used on data belonging to nominal and ordinal scale types. We provide an informal introduction to representational measurement theory and argue for its importance in robust scientific inquiry. Although measurement theory is widely applicable in paleobiology research, we use the study of disparity to illustrate measurement theoretical challenges in the quantitative study of the fossil record. Respecting the inherent properties of different measurements enables meaningful inferences about evolutionary and ecological processes from paleontological data.
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Affiliation(s)
| | | | | | | | - Alexis Rojas
- Department of Computer Science, University of Helsinki, Helsinki, Finland
| | | | | | - Connor J Wilson
- Natural History Museum, University of Oslo, Oslo, Norway; School of Geography and the Environment, University of Oxford, Oxford, UK
| | - Erin E Saupe
- Department of Earth Sciences, University of Oxford, Oxford, UK
| | - Mark Grabowski
- Research Centre in Evolutionary Anthropology and Paleoecology, Liverpool John Moores University, Liverpool, UK
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6
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Laboury A, Scheyer TM, Klein N, Stubbs TL, Fischer V. High phenotypic plasticity at the dawn of the eosauropterygian radiation. PeerJ 2023; 11:e15776. [PMID: 37671356 PMCID: PMC10476616 DOI: 10.7717/peerj.15776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Accepted: 06/29/2023] [Indexed: 09/07/2023] Open
Abstract
The initial radiation of Eosauropterygia during the Triassic biotic recovery represents a key event in the dominance of reptiles secondarily adapted to marine environments. Recent studies on Mesozoic marine reptile disparity highlighted that eosauropterygians had their greatest morphological diversity during the Middle Triassic, with the co-occurrence of Pachypleurosauroidea, Nothosauroidea and Pistosauroidea, mostly along the margins of the Tethys Ocean. However, these previous studies quantitatively analysed the disparity of Eosauropterygia as a whole without focussing on Triassic taxa, thus limiting our understanding of their diversification and morphospace occupation during the Middle Triassic. Our multivariate morphometric analyses highlight a clearly distinct colonization of the ecomorphospace by the three clades, with no evidence of whole-body convergent evolution with the exception of the peculiar pistosauroid Wangosaurus brevirostris, which appears phenotypically much more similar to nothosauroids. This global pattern is mostly driven by craniodental differences and inferred feeding specializations. We also reveal noticeable regional differences among nothosauroids and pachypleurosauroids of which the latter likely experienced a remarkable diversification in the eastern Tethys during the Pelsonian. Our results demonstrate that the high phenotypic plasticity characterizing the evolution of the pelagic plesiosaurians was already present in their Triassic ancestors, casting eosauropterygians as particularly adaptable animals.
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Affiliation(s)
- Antoine Laboury
- Evolution & Diversity Dynamics Lab, Université de Liège, Liège, Belgium
| | | | - Nicole Klein
- Institute of Geosciences, Paleontology, University of Bonn, Bonn, Germany
| | - Thomas L. Stubbs
- School of Life, Health & Chemical Sciences, Open University, Milton Keynes, United Kingdom
| | - Valentin Fischer
- Evolution & Diversity Dynamics Lab, Université de Liège, Liège, Belgium
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7
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Smith TJ, Sansom RS, Pisani D, Donoghue PCJ. Fossilization can mislead analyses of phenotypic disparity. Proc Biol Sci 2023; 290:20230522. [PMID: 37554036 PMCID: PMC10410227 DOI: 10.1098/rspb.2023.0522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Accepted: 07/20/2023] [Indexed: 08/10/2023] Open
Abstract
Analyses of morphological disparity can incorporate living and fossil taxa to facilitate the exploration of how phenotypic variation changes through time. However, taphonomic processes introduce non-random patterns of data loss in fossil data and their impact on perceptions of disparity is unclear. To address this, we characterize how measures of disparity change when simulated and empirical data are degraded through random and structured data loss. We demonstrate that both types of data loss can distort the disparity of clades, and that the magnitude and direction of these changes varies between the most commonly employed distance metrics and disparity indices. The inclusion of extant taxa and exceptionally preserved fossils mitigates these distortions and clarifies the full extent of the data lost, most of which would otherwise go uncharacterized. This facilitates the use of ancestral state estimation and evolutionary simulations to further control for the effects of data loss. Where the addition of such reference taxa is not possible, we urge caution in the extrapolation of general patterns in disparity from datasets that characterize subsets of phenotype, which may represent no more than the traits that they sample.
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Affiliation(s)
- Thomas J. Smith
- Bristol Palaeobiology Group, School of Earth Sciences, University of Bristol, Life Sciences Building, Tyndall Avenue, Bristol BS8 1TQ, UK
- Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, UK
| | - Robert S. Sansom
- Department of Earth and Environmental Sciences, University of Manchester, Williamson Building, Oxford Road, Manchester M13 9PL, UK
| | - Davide Pisani
- Bristol Palaeobiology Group, School of Earth Sciences, University of Bristol, Life Sciences Building, Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Philip C. J. Donoghue
- Bristol Palaeobiology Group, School of Earth Sciences, University of Bristol, Life Sciences Building, Tyndall Avenue, Bristol BS8 1TQ, UK
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8
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Jamison-Todd S, Moon BC, Rowe AJ, Williams M, Benton MJ. Dietary niche partitioning in Early Jurassic ichthyosaurs from Strawberry Bank. J Anat 2022; 241:1409-1423. [PMID: 36175086 DOI: 10.1111/joa.13744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 08/02/2022] [Accepted: 08/02/2022] [Indexed: 11/29/2022] Open
Abstract
Jurassic ichthyosaurs dominated upper trophic levels of marine ecosystems. Many species coexisted alongside each another, and it is uncertain whether they competed for the same array of food or divided dietary resources, each specializing in different kinds of prey. Here, we test whether feeding differences existed between species, applying finite element analysis to ichthyosaurs for the first time. We examine two juvenile ichthyosaur specimens, referred to Hauffiopteryx typicus and Stenopterygius triscissus, from the Strawberry Bank Lagerstätte, a shallow marine environment from the Early Jurassic of southern England (Toarcian, ~183 Ma). Snout and cranial robusticity differ between the species, with S. triscissus having a more robust snout and cranium and specializing in slow biting of hard prey, and H. typicus with its slender snout specializing in fast, but weaker bites on fast-moving, but soft prey. The two species did not differ in muscle forces, but stress distributions varied in the nasal area, reflecting differences when biting at different points along the tooth row: the more robustly snouted Stenopterygius resisted increases or shifts in stress distribution when the bite point was shifted from the posterior to the mid-point of the tooth row, but the slender-snouted Hauffiopteryx showed shifts and increases in stress distributions between these two bite points. The differences in cranial morphology, dentition and inferred stresses between the two species suggest adaptations for dietary niche partitioning.
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Affiliation(s)
| | - Benjamin C Moon
- Bristol Palaeobiology Group, School of Earth Sciences, University of Bristol, Bristol, UK
| | - Andre J Rowe
- Bristol Palaeobiology Group, School of Earth Sciences, University of Bristol, Bristol, UK
| | - Matt Williams
- Bath Royal Literary and Scientific Institution, Bath, UK
| | - Michael J Benton
- Bristol Palaeobiology Group, School of Earth Sciences, University of Bristol, Bristol, UK
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9
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Laboury A, Bennion RF, Thuy B, Weis R, Fischer V. Anatomy and phylogenetic relationships of Temnodontosaurus zetlandicus (Reptilia: Ichthyosauria). Zool J Linn Soc 2022. [DOI: 10.1093/zoolinnean/zlab118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Abstract
Parvipelvia is a major clade of ichthyosaurians that diversified during the Triassic-Jurassic transition. The interrelationships of early parvipelvians remain unclear and many genera are loosely diagnosed, such as Temnodontosaurus, an ecologically important genus from the Early Jurassic of Western Europe. One taxon concentrates many taxonomic issues: ‘Ichthyosaurus’ acutirostris was previously assigned to Temnodontosaurus and for which ‘Ichthyosaurus’ zetlandicus represents a junior synonym. We redescribe the holotype of ‘Ichthyosaurus’ zetlandicus (CAMSM J35176) and a new specimen probably attributable to this taxon (MNHNL TU885) from the Toarcian of Luxembourg. We find that Temnodontosaurus zetlandicus comb. nov. is a valid species that should be referred to the genus Temnodontosaurus, sharing a number of traits with Temnodontosaurus nuertingensis and Temnodontosaurus trigonodon, despite having a distinct cranial architecture. Our phylogenetic analyses under both implied weighting maximum parsimony and Bayesian inference recover T. zetlandicus as closely related to several species currently assigned to Temnodontosaurus. Species included in Temnodontosaurus form a polyphyletic yet well-clustered group among basal neoichthyosaurians, demonstrating that the monophyly of this genus needs to be thoroughly investigated.
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Affiliation(s)
- Antoine Laboury
- Evolution & Diversity Dynamics Lab, University of Liège, 14 Allée du 6 Août, Liège 4000, Belgium
| | - Rebecca F Bennion
- Evolution & Diversity Dynamics Lab, University of Liège, 14 Allée du 6 Août, Liège 4000, Belgium
- Palaeontology Department, Royal Belgian Institute of Natural Sciences, 29, Rue Vautier, 1000 Brussels, Belgium
| | - Ben Thuy
- Palaeontology Departement, Natural History Museum Luxembourg, 25 Rue Münster, L-2160 Luxembourg, Grand-Duchy of Luxembourg
| | - Robert Weis
- Palaeontology Departement, Natural History Museum Luxembourg, 25 Rue Münster, L-2160 Luxembourg, Grand-Duchy of Luxembourg
| | - Valentin Fischer
- Evolution & Diversity Dynamics Lab, University of Liège, 14 Allée du 6 Août, Liège 4000, Belgium
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10
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Delsett LL, Pyenson ND. Early and fast rise of Mesozoic ocean giants. Science 2021; 374:1554-1555. [PMID: 34941421 DOI: 10.1126/science.abm3751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
[Figure: see text].
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Affiliation(s)
- Lene Liebe Delsett
- Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.,Natural History Museum, University of Oslo, Oslo, Norway
| | - Nicholas D Pyenson
- Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.,Burke Museum of Natural History and Culture, Seattle, WA, USA
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11
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Fischer V, Weis R, Thuy B. Refining the marine reptile turnover at the Early-Middle Jurassic transition. PeerJ 2021; 9:e10647. [PMID: 33665003 PMCID: PMC7906043 DOI: 10.7717/peerj.10647] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Accepted: 12/04/2020] [Indexed: 11/21/2022] Open
Abstract
Even though a handful of long-lived reptilian clades dominated Mesozoic marine ecosystems, several biotic turnovers drastically changed the taxonomic composition of these communities. A seemingly slow paced, within-geological period turnover took place across the Early–Middle Jurassic transition. This turnover saw the demise of early neoichthyosaurians, rhomaleosaurid plesiosaurians and early plesiosauroids in favour of ophthalmosaurid ichthyosaurians and cryptoclidid and pliosaurid plesiosaurians, clades that will dominate the Late Jurassic and, for two of them, the entire Early Cretaceous as well. The fossil record of this turnover is however extremely poor and this change of dominance appears to be spread across the entire middle Toarcian–Bathonian interval. We describe a series of ichthyosaurian and plesiosaurian specimens from successive geological formations in Luxembourg and Belgium that detail the evolution of marine reptile assemblages across the Early–Middle Jurassic transition within a single area, the Belgo–Luxembourgian sub-basin. These fossils reveal the continuing dominance of large rhomaleosaurid plesiosaurians, microcleidid plesiosaurians and Temnodontosaurus-like ichthyosaurians up to the latest Toarcian, indicating that the structuration of the upper tier of Western Europe marine ecosystems remained essentially constant up to the very end of the Early Jurassic. These fossils also suddenly record ophthalmosaurid ichthyosaurians and cryptoclidid plesiosaurians by the early Bajocian. These results from a geographically-restricted area provide a clearer picture of the shape of the marine reptile turnover occurring at the early–Middle Jurassic transition. This event appears restricted to the sole Aalenian stage, reducing the uncertainty of its duration, at least for ichthyosaurians and plesiosaurians, to 4 instead of 14 million years.
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Affiliation(s)
- Valentin Fischer
- Evolution & Diversity Dynamics Lab, UR Geology, Université de Liège, Liège, Belgium
| | - Robert Weis
- Department of palaeontology, Natural History Museum Luxembourg, Luxembourg, Grand-Duchy of Luxembourg
| | - Ben Thuy
- Department of palaeontology, Natural History Museum Luxembourg, Luxembourg, Grand-Duchy of Luxembourg
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12
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Verberk WCEP, Calosi P, Brischoux F, Spicer JI, Garland T, Bilton DT. Universal metabolic constraints shape the evolutionary ecology of diving in animals. Proc Biol Sci 2020; 287:20200488. [PMID: 32453989 PMCID: PMC7287373 DOI: 10.1098/rspb.2020.0488] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 04/27/2020] [Indexed: 01/07/2023] Open
Abstract
Diving as a lifestyle has evolved on multiple occasions when air-breathing terrestrial animals invaded the aquatic realm, and diving performance shapes the ecology and behaviour of all air-breathing aquatic taxa, from small insects to great whales. Using the largest dataset yet assembled, we show that maximum dive duration increases predictably with body mass in both ectotherms and endotherms. Compared to endotherms, ectotherms can remain submerged for longer, but the mass scaling relationship for dive duration is much steeper in endotherms than in ectotherms. These differences in diving allometry can be fully explained by inherent differences between the two groups in their metabolic rate and how metabolism scales with body mass and temperature. Therefore, we suggest that similar constraints on oxygen storage and usage have shaped the evolutionary ecology of diving in all air-breathing animals, irrespective of their evolutionary history and metabolic mode. The steeper scaling relationship between body mass and dive duration in endotherms not only helps explain why the largest extant vertebrate divers are endothermic rather than ectothermic, but also fits well with the emerging consensus that large extinct tetrapod divers (e.g. plesiosaurs, ichthyosaurs and mosasaurs) were endothermic.
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Affiliation(s)
- Wilco C E P Verberk
- Department of Animal Ecology and Ecophysiology, Radboud University, PO Box 9010, 6500 GL Nijmegen, The Netherlands
- Marine Biology and Ecology Research Centre, School of Biological and Marine Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA, UK
| | - Piero Calosi
- Marine Biology and Ecology Research Centre, School of Biological and Marine Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA, UK
- Département de Biologie, Chimie et Géographie, Université du Québec à Rimouski, 300 Allée des Ursulines, Rimouski, Québec, Canada G5 L 3A1
| | - François Brischoux
- Centre d'Etudes Biologiques de Chizé, UMR 7372 CNRS-La Rochelle Université, 79360 Villiers en Bois, France
| | - John I Spicer
- Marine Biology and Ecology Research Centre, School of Biological and Marine Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA, UK
| | - Theodore Garland
- Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, CA 92521, USA
| | - David T Bilton
- Marine Biology and Ecology Research Centre, School of Biological and Marine Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA, UK
- Department of Zoology, University of Johannesburg, PO Box 524, Auckland Park, 2006 Johannesburg, South Africa
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Moon BC, Stubbs TL. Early high rates and disparity in the evolution of ichthyosaurs. Commun Biol 2020; 3:68. [PMID: 32054967 PMCID: PMC7018711 DOI: 10.1038/s42003-020-0779-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Accepted: 01/07/2020] [Indexed: 12/02/2022] Open
Abstract
How clades diversify early in their history is integral to understanding the origins of biodiversity and ecosystem recovery following mass extinctions. Moreover, diversification can represent evolutionary opportunities and pressures following ecosystem changes. Ichthyosaurs, Mesozoic marine reptiles, appeared after the end-Permian mass extinction and provide opportunities to assess clade diversification in a changed world. Using recent cladistic data, skull length data, and the most complete phylogenetic trees to date for the group, we present a combined disparity, morphospace, and evolutionary rates analysis that reveals the tempo and mode of ichthyosaur morphological evolution through 160 million years. Ichthyosaur evolution shows an archetypal early burst trend, driven by ecological opportunity in Triassic seas, and an evolutionary bottleneck leading to a long-term reduction in evolutionary rates and disparity. This is represented consistently across all analytical methods by a Triassic peak in ichthyosaur disparity and evolutionary rates, and morphospace separation between Triassic and post-Triassic taxa.
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Affiliation(s)
- Benjamin C Moon
- Palaeobiology Research Group, University of Bristol, Life Sciences Building, 24 Tyndall Avenue, Bristol, BS8 1TQ, UK.
| | - Thomas L Stubbs
- Palaeobiology Research Group, University of Bristol, Life Sciences Building, 24 Tyndall Avenue, Bristol, BS8 1TQ, UK
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14
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Gillet A, Frédérich B, Parmentier E. Divergent evolutionary morphology of the axial skeleton as a potential key innovation in modern cetaceans. Proc Biol Sci 2019; 286:20191771. [PMID: 31771481 PMCID: PMC6939272 DOI: 10.1098/rspb.2019.1771] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 10/30/2019] [Indexed: 11/12/2022] Open
Abstract
Cetaceans represent the most diverse clade of extant marine tetrapods. Although the restructuring of oceans could have contributed to their diversity, other factors might also be involved. Similar to ichthyosaurs and sharks, variation of morphological traits could have promoted the colonization of new ecological niches and supported their diversification. By combining morphological data describing the axial skeleton of 73 cetacean species with phylogenetic comparative methods, we demonstrate that the vertebral morphology of cetaceans is associated with their habitat. All riverine and coastal species possess a small body size, lengthened vertebrae and a low vertebral count compared with open ocean species. Extant cetaceans have followed two distinct evolutionary pathways relative to their ecology. Whereas most offshore species such as baleen whales evolved towards an increased body size while retaining a low vertebral count, small oceanic dolphins underwent deep modifications of their axial skeleton with an extremely high number of short vertebrae. Our comparative analyses provide evidence these vertebral modifications have potentially operated as key innovations. These novelties contributed to their explosive radiation, resulting in an efficient swimming style that provides energetic advantages to small-sized species.
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Affiliation(s)
- Amandine Gillet
- Laboratory of Functional and Evolutionary Morphology, University of Liège, Liège, Belgium
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15
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Climate cooling and clade competition likely drove the decline of lamniform sharks. Proc Natl Acad Sci U S A 2019; 116:20584-20590. [PMID: 31548392 DOI: 10.1073/pnas.1902693116] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Understanding heterogeneity in species richness between closely related clades is a key research question in ecology and evolutionary biology. Multiple hypotheses have been proposed to interpret such diversity contrasts across the tree of life, with most studies focusing on speciation rates to explain clades' evolutionary radiations, while often neglecting extinction rates. Here we study a notorious biological model as exemplified by the sister relationships between mackerel sharks (Lamniformes, 15 extant species) and ground sharks (Carcharhiniformes, ∼290 extant species). Using a comprehensive fossil dataset, we found that the diversity dynamics of lamniforms waxed and waned following repeated cycles of radiation phases and declining phases. Radiation phases peaked up to 3 times the current diversity in the early Late Cretaceous. In the last 20 million years, the group declined to its present-day diversity. Along with a higher extinction risk for young species, we further show that this declining pattern is likely attributed to a combination of abiotic and biotic factors, with a cooling-driven extinction (negative correlation between temperature and extinction) and clade competition with some ground sharks. Competition from multiple clades successively drove the demise and replacement of mackerel sharks due to a failure to originate facing the rise of ground sharks, particularly since the Eocene. These effects came from ecologically similar carcharhiniform species inhibiting diversification of medium- and large-sized lamniforms. These results imply that the interplay between abiotic and biotic drivers had a substantial role in extinction and speciation, respectively, which determines the sequential rise and decline of marine apex predators.
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16
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Smithwick FM, Stubbs TL. Phanerozoic survivors: Actinopterygian evolution through the Permo-Triassic and Triassic-Jurassic mass extinction events. Evolution 2019; 72:348-362. [PMID: 29315531 PMCID: PMC5817399 DOI: 10.1111/evo.13421] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 12/19/2017] [Accepted: 12/19/2017] [Indexed: 11/29/2022]
Abstract
Actinopterygians (ray‐finned fishes) successfully passed through four of the big five mass extinction events of the Phanerozoic, but the effects of these crises on the group are poorly understood. Many researchers have assumed that the Permo‐Triassic mass extinction (PTME) and end‐Triassic extinction (ETE) had little impact on actinopterygians, despite devastating many other groups. Here, two morphometric techniques, geometric (body shape) and functional (jaw morphology), are used to assess the effects of these two extinction events on the group. The PTME elicits no significant shifts in functional disparity while body shape disparity increases. An expansion of body shape and functional disparity coincides with the neopterygian radiation and evolution of novel feeding adaptations in the Middle‐Late Triassic. Through the ETE, small decreases are seen in shape and functional disparity, but are unlikely to represent major changes brought about by the extinction event. In the Early Jurassic, further expansions into novel areas of ecospace indicative of durophagy occur, potentially linked to losses in the ETE. As no evidence is found for major perturbations in actinopterygian evolution through either extinction event, the group appears to have been immune to two major environmental crises that were disastrous to most other organisms.
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Affiliation(s)
- Fiann M Smithwick
- Department of Earth Sciences, University of Bristol, Bristol BS8 1TQ, United Kingdom
| | - Thomas L Stubbs
- Department of Earth Sciences, University of Bristol, Bristol BS8 1TQ, United Kingdom
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17
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Flannery Sutherland JT, Moon BC, Stubbs TL, Benton MJ. Does exceptional preservation distort our view of disparity in the fossil record? Proc Biol Sci 2019; 286:20190091. [PMID: 30963850 PMCID: PMC6408902 DOI: 10.1098/rspb.2019.0091] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 02/04/2019] [Indexed: 11/12/2022] Open
Abstract
How much of evolutionary history is lost because of the unevenness of the fossil record? Lagerstätten, sites which have historically yielded exceptionally preserved fossils, provide remarkable, yet distorting insights into past life. When examining macroevolutionary trends in the fossil record, they can generate an uneven sampling signal for taxonomic diversity; by comparison, their effect on morphological variety (disparity) is poorly understood. We show here that lagerstätten impact the disparity of ichthyosaurs, Mesozoic marine reptiles, by preserving higher diversity and more complete specimens. Elsewhere in the fossil record, undersampled diversity and more fragmentary specimens produce spurious results. We identify a novel effect, that a taxon moves towards the centroid of a Generalized Euclidean dataset as its proportion of missing data increases. We term this effect 'centroid slippage', as a disparity-based analogue of phylogenetic stemward slippage. Our results suggest that uneven sampling presents issues for our view of disparity in the fossil record, but that this is also dependent on the methodology used, especially true with widely used Generalized Euclidean distances. Mitigation of missing cladistic data is possible by phylogenetic gap filling, and heterogeneous effects of lagerstätten on disparity may be accounted for by understanding the factors affecting their spatio-temporal distribution.
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18
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Dunhill AM, Foster WJ, Azaele S, Sciberras J, Twitchett RJ. Modelling determinants of extinction across two Mesozoic hyperthermal events. Proc Biol Sci 2018; 285:rspb.2018.0404. [PMID: 30355705 DOI: 10.1098/rspb.2018.0404] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Accepted: 10/08/2018] [Indexed: 11/12/2022] Open
Abstract
The Late Triassic and Early Toarcian extinction events are both associated with greenhouse warming events triggered by massive volcanism. These Mesozoic hyperthermals were responsible for the mass extinction of marine organisms and resulted in significant ecological upheaval. It has, however, been suggested that these events merely involved intensification of background extinction rates rather than significant shifts in the macroevolutionary regime and extinction selectivity. Here, we apply a multivariate modelling approach to a vast global database of marine organisms to test whether extinction selectivity varied through the Late Triassic and Early Jurassic. We show that these hyperthermals do represent shifts in the macroevolutionary regime and record different extinction selectivity compared to background intervals of the Late Triassic and Early Jurassic. The Late Triassic mass extinction represents a more profound change in selectivity than the Early Toarcian extinction but both events show a common pattern of selecting against pelagic predators and benthic photosymbiotic and suspension-feeding organisms, suggesting that these groups of organisms may be particularly vulnerable during episodes of global warming. In particular, the Late Triassic extinction represents a macroevolutionary regime change that is characterized by (i) the change in extinction selectivity between Triassic background intervals and the extinction event itself; and (ii) the differences in extinction selectivity between the Late Triassic and Early Jurassic as a whole.
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Affiliation(s)
| | - William J Foster
- Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Berlin, Deutschland
| | - Sandro Azaele
- School of Mathematics, University of Leeds, Leeds LS2 9JT, UK
| | - James Sciberras
- OnCorps, Exeter House, Lower Station Approach, Temple Meads, Bristol BS1 6QS, UK
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19
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Sidle RC, Gomi T, Akasaka M, Koyanagi K. Ecosystem changes following the 2016 Kumamoto earthquakes in Japan: Future perspectives. AMBIO 2018; 47:721-734. [PMID: 29288415 PMCID: PMC6131130 DOI: 10.1007/s13280-017-1005-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 11/13/2017] [Accepted: 12/14/2017] [Indexed: 06/07/2023]
Abstract
Major earthquakes cause widespread environmental and socioeconomic disruptions that persist for decades. Extensive ground disturbances that occurred during the shallow-focus Kumamoto earthquakes will affect future sustainability of ecosystem services west of Aso volcano. Numbers of earthquake-initiated landslides per unit area were higher in grasslands than forests, likely owing to greater root reinforcement of trees, and mostly initiated on ridgelines and/or convex/planar hillslopes. Most landslides traveled short distances and did not initially evolve into debris flows; resultant sediments and wood accumulating in headwater channels can be mobilized into debris flows during future storms. Fissures along ridgelines may promote water ingress and induce future landslides and debris flows that affect residents downstream. Native grasses are at risk because of habitat fragmentation caused by ground disturbances, extensive damage to rural roads, and abandonment of traditional pasture management practices. Sustainable management of affected areas needs to consider future risk of cascading hazards and long-term socioeconomic impacts.
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Affiliation(s)
- Roy C. Sidle
- Sustainability Research Centre, University of the Sunshine Coast, 90 Sippy Downs Dr., Sippy Downs, QLD 4556 Australia
- Institute of Global Innovation Research, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-5809 Japan
| | - Takashi Gomi
- Department of International Environmental and Agricultural Science, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-5809 Japan
- Institute of Global Innovation Research, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-5809 Japan
| | - Munemitsu Akasaka
- Institute of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-5809 Japan
| | - Kenta Koyanagi
- Faculty of Science and Forestry, University of Eastern Finland, Yliopistokatu 2, 80100 Joensuu, Finland
- Tokyo University of Agriculture and Technology, Fuchu, Tokyo Japan
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20
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Lomax DR, De la Salle P, Massare JA, Gallois R. A giant Late Triassic ichthyosaur from the UK and a reinterpretation of the Aust Cliff 'dinosaurian' bones. PLoS One 2018; 13:e0194742. [PMID: 29630618 PMCID: PMC5890986 DOI: 10.1371/journal.pone.0194742] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Accepted: 03/08/2018] [Indexed: 11/21/2022] Open
Abstract
The largest reported ichthyosaurs lived during the Late Triassic (~235–200 million years ago), and isolated, fragmentary bones could be easily mistaken for those of dinosaurs because of their size. We report the discovery of an isolated bone from the lower jaw of a giant ichthyosaur from the latest Triassic of Lilstock, Somerset, UK. It documents that giant ichthyosaurs persisted well into the Rhaetian Stage, and close to the time of the Late Triassic extinction event. This specimen has prompted the reinterpretation of several large, roughly cylindrical bones from the latest Triassic (Rhaetian Stage) Westbury Mudstone Formation from Aust Cliff, Gloucestershire, UK. We argue here that the Aust bones, previously identified as those of dinosaurs or large terrestrial archosaurs, are jaw fragments from giant ichthyosaurs. The Lilstock and Aust specimens might represent the largest ichthyosaurs currently known.
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Affiliation(s)
- Dean R. Lomax
- School of Earth and Environmental Sciences, The University of Manchester, Oxford Road, Manchester, United Kingdom
- * E-mail:
| | - Paul De la Salle
- The Etches Collection–Museum of Jurassic Marine Life, Dorset, United Kingdom
| | - Judy A. Massare
- Department of the Earth Sciences, State University of New York, College at Brockport, Brockport, NY, United States of America
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21
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Prasad GVR, Pandey DK, Alberti M, Fürsich FT, Thakkar MG, Chauhan GD. Discovery of the first ichthyosaur from the Jurassic of India: Implications for Gondwanan palaeobiogeography. PLoS One 2017; 12:e0185851. [PMID: 29069082 PMCID: PMC5656312 DOI: 10.1371/journal.pone.0185851] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Accepted: 09/20/2017] [Indexed: 11/18/2022] Open
Abstract
An articulated and partially preserved skeleton of an ichthyosaur was found in the Upper Jurassic (Upper Kimmeridgian) Katrol Formation exposed at a site south of the village Lodai in Kachchh district, Gujarat (western India). Here we present a detailed description and inferred taxonomic relationship of the specimen. The present study revealed that the articulated skeleton belongs to the family Ophthalmosauridae. The new discovery from India further improves the depauperate fossil record of ichthyosaurs from the former Gondwanan continents. Based on the preserved length of the axial skeleton and anterior part of the snout and taking into account the missing parts of the skull and postflexural region, it is suggested that the specimen may represent an adult possibly reaching a length of 5.0–5.5 m. The widespread occurrence of ophthalmosaurids in the Upper Jurassic deposits of western Tethys, Madagascar, South America and India points to possible faunal exchanges between the western Tethys and Gondwanan continents through a southern seaway.
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Affiliation(s)
- Guntupalli V. R. Prasad
- Department of Geology, Centre for Advanced Studies, University of Delhi, Delhi, India
- * E-mail:
| | - Dhirendra K. Pandey
- Earth and Planetary Sciences Group, Manipal Center for Natural Sciences, Manipal University, Manipal, Karnataka, India
| | - Matthias Alberti
- Institut für Geowissenschaften, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
| | - Franz T. Fürsich
- GeoZentrum Nordbayern, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Mahesh G. Thakkar
- Department of Earth and Environmental Science, KSKV Kachchh University, Bhuj, India
| | - Gaurav D. Chauhan
- Department of Earth and Environmental Science, KSKV Kachchh University, Bhuj, India
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22
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Congreve CR, Falk AR, Lamsdell JC. Biological hierarchies and the nature of extinction. Biol Rev Camb Philos Soc 2017; 93:811-826. [DOI: 10.1111/brv.12368] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 08/18/2017] [Accepted: 08/22/2017] [Indexed: 01/26/2023]
Affiliation(s)
- Curtis R. Congreve
- Department of Geosciences; 510 Deike Building, Pennsylvania State University; University Park PA 16802 U.S.A
| | - Amanda R. Falk
- Department of Biology; Centre College, 600 West Walnut Street; Danville KY 40422 U.S.A
| | - James C. Lamsdell
- Department of Geology and Geography, 98 Beechurst Avenure, Brooks Hall; West Virginia University; Morgantown WV 26506 U.S.A
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23
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Lamsdell JC, Selden PA. From success to persistence: Identifying an evolutionary regime shift in the diverse Paleozoic aquatic arthropod group Eurypterida, driven by the Devonian biotic crisis. Evolution 2016; 71:95-110. [PMID: 27783385 DOI: 10.1111/evo.13106] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Revised: 10/12/2016] [Accepted: 10/21/2016] [Indexed: 01/03/2023]
Abstract
Mass extinctions have altered the trajectory of evolution a number of times over the Phanerozoic. During these periods of biotic upheaval a different selective regime appears to operate, although it is still unclear whether consistent survivorship rules apply across different extinction events. We compare variations in diversity and disparity across the evolutionary history of a major Paleozoic arthropod group, the Eurypterida. Using these data, we explore the group's transition from a successful, dynamic clade to a stagnant persistent lineage, pinpointing the Devonian as the period during which this evolutionary regime shift occurred. The late Devonian biotic crisis is potentially unique among the "Big Five" mass extinctions in exhibiting a drop in speciation rates rather than an increase in extinction. Our study reveals eurypterids show depressed speciation rates throughout the Devonian but no abnormal peaks in extinction. Loss of morphospace occupation is random across all Paleozoic extinction events; however, differential origination during the Devonian results in a migration and subsequent stagnation of occupied morphospace. This shift appears linked to an ecological transition from euryhaline taxa to freshwater species with low morphological diversity alongside a decrease in endemism. These results demonstrate the importance of the Devonian biotic crisis in reshaping Paleozoic ecosystems.
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Affiliation(s)
- James C Lamsdell
- Division of Paleontology, American Museum of Natural History, Central Park West at 79th Street, New York, New York, 10024.,Department of Geology and Geography, West Virginia University, 98 Beechurst Avenue, Brooks Hall, Morgantown, West Virginia, 26506
| | - Paul A Selden
- Paleontological Institute and Department of Geology, University of Kansas, 1475 Jayhawk Boulevard, Lawrence, Kansas, 66045.,Natural History Museum, Cromwell Road, London, SW7 5BD, United Kingdom
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24
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Dick DG, Maxwell EE. The evolution and extinction of the ichthyosaurs from the perspective of quantitative ecospace modelling. Biol Lett 2016; 11:rsbl.2015.0339. [PMID: 26156130 DOI: 10.1098/rsbl.2015.0339] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The role of niche specialization and narrowing in the evolution and extinction of the ichthyosaurs has been widely discussed in the literature. However, previous studies have concentrated on a qualitative discussion of these variables only. Here, we use the recently developed approach of quantitative ecospace modelling to provide a high-resolution quantitative examination of the changes in dietary and ecological niche experienced by the ichthyosaurs throughout their evolution in the Mesozoic. In particular, we demonstrate that despite recent discoveries increasing our understanding of taxonomic diversity among the ichthyosaurs in the Cretaceous, when viewed from the perspective of ecospace modelling, a clear trend of ecological contraction is visible as early as the Middle Jurassic. We suggest that this ecospace redundancy, if carried through to the Late Cretaceous, could have contributed to the extinction of the ichthyosaurs. Additionally, our results suggest a novel model to explain ecospace change, termed the 'migration model'.
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25
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Oyston JW, Hughes M, Gerber S, Wills MA. Why should we investigate the morphological disparity of plant clades? ANNALS OF BOTANY 2016; 117:859-79. [PMID: 26658292 PMCID: PMC4845799 DOI: 10.1093/aob/mcv135] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Revised: 05/28/2015] [Accepted: 07/08/2015] [Indexed: 05/10/2023]
Abstract
BACKGROUND Disparity refers to the morphological variation in a sample of taxa, and is distinct from diversity or taxonomic richness. Diversity and disparity are fundamentally decoupled; many groups attain high levels of disparity early in their evolution, while diversity is still comparatively low. Diversity may subsequently increase even in the face of static or declining disparity by increasingly fine sub-division of morphological 'design' space (morphospace). Many animal clades reached high levels of disparity early in their evolution, but there have been few comparable studies of plant clades, despite their profound ecological and evolutionary importance. This study offers a prospective and some preliminary macroevolutionary analyses. METHODS Classical morphometric methods are most suitable when there is reasonable conservation of form, but lose traction where morphological differences become greater (e.g. in comparisons across higher taxa). Discrete character matrices offer one means to compare a greater diversity of forms. This study explores morphospaces derived from eight discrete data sets for major plant clades, and discusses their macroevolutionary implications. KEY RESULTS Most of the plant clades in this study show initial, high levels of disparity that approach or attain the maximum levels reached subsequently. These plant clades are characterized by an initial phase of evolution during which most regions of their empirical morphospaces are colonized. Angiosperms, palms, pines and ferns show remarkably little variation in disparity through time. Conifers furnish the most marked exception, appearing at relatively low disparity in the latest Carboniferous, before expanding incrementally with the radiation of successive, tightly clustered constituent sub-clades. CONCLUSIONS Many cladistic data sets can be repurposed for investigating the morphological disparity of plant clades through time, and offer insights that are complementary to more focused morphometric studies. The unique structural and ecological features of plants make them ideally suited to investigating intrinsic and extrinsic constraints on disparity.
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Affiliation(s)
- Jack W Oyston
- Milner Centre for Evolution, University of Bath, Bath BA2 7AY, UK
| | - Martin Hughes
- Department of Life Sciences, The Natural History Museum, London SW7 5BD, UK and
| | - Sylvain Gerber
- Department of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ, UK
| | - Matthew A Wills
- Milner Centre for Evolution, University of Bath, Bath BA2 7AY, UK,
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26
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Extinction of fish-shaped marine reptiles associated with reduced evolutionary rates and global environmental volatility. Nat Commun 2016; 7:10825. [PMID: 26953824 PMCID: PMC4786747 DOI: 10.1038/ncomms10825] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Accepted: 01/22/2016] [Indexed: 11/08/2022] Open
Abstract
Despite their profound adaptations to the aquatic realm and their apparent success throughout the Triassic and the Jurassic, ichthyosaurs became extinct roughly 30 million years before the end-Cretaceous mass extinction. Current hypotheses for this early demise involve relatively minor biotic events, but are at odds with recent understanding of the ichthyosaur fossil record. Here, we show that ichthyosaurs maintained high but diminishing richness and disparity throughout the Early Cretaceous. The last ichthyosaurs are characterized by reduced rates of origination and phenotypic evolution and their elevated extinction rates correlate with increased environmental volatility. In addition, we find that ichthyosaurs suffered from a profound Early Cenomanian extinction that reduced their ecological diversity, likely contributing to their final extinction at the end of the Cenomanian. Our results support a growing body of evidence revealing that global environmental change resulted in a major, temporally staggered turnover event that profoundly reorganized marine ecosystems during the Cenomanian. The extinction of the ichthyosaurs had previously been attributed to increasing competition or to the loss of their main prey. Here, Fischer et al. analyse phylogenetic and ecological patterns of ichthyosaur diversification and extinction, and find that the decline of the group is more likely due to climatic volatility.
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27
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Lloyd GT. Estimating morphological diversity and tempo with discrete character-taxon matrices: implementation, challenges, progress, and future directions. Biol J Linn Soc Lond 2016. [DOI: 10.1111/bij.12746] [Citation(s) in RCA: 128] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Graeme T. Lloyd
- Department of Biological Sciences; Faculty of Science; Macquarie University; NSW 2109 Australia
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28
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Halliday TJD, Goswami A. Eutherian morphological disparity across the end-Cretaceous mass extinction. Biol J Linn Soc Lond 2015. [DOI: 10.1111/bij.12731] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Thomas John Dixon Halliday
- Department of Earth Sciences; University College London; Gower Street London WC1E 6BT UK
- Department of Genetics, Evolution, and Environment; University College London; Gower Street London WC1E 6BT UK
| | - Anjali Goswami
- Department of Earth Sciences; University College London; Gower Street London WC1E 6BT UK
- Department of Genetics, Evolution, and Environment; University College London; Gower Street London WC1E 6BT UK
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29
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Benton MJ. Exploring macroevolution using modern and fossil data. Proc Biol Sci 2015; 282:20150569. [PMID: 26063844 PMCID: PMC4590474 DOI: 10.1098/rspb.2015.0569] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 05/12/2015] [Indexed: 01/24/2023] Open
Abstract
Macroevolution, encompassing the deep-time patterns of the origins of modern biodiversity, has been discussed in many contexts. Non-Darwinian models such as macromutations have been proposed as a means of bridging seemingly large gaps in knowledge, or as a means to explain the origin of exquisitely adapted body plans. However, such gaps can be spanned by new fossil finds, and complex, integrated organisms can be shown to have evolved piecemeal. For example, the fossil record between dinosaurs and Archaeopteryx has now filled up with astonishing fossil intermediates that show how the unique plexus of avian adaptations emerged step by step over 60 Myr. New numerical approaches to morphometrics and phylogenetic comparative methods allow palaeontologists and biologists to work together on deep-time questions of evolution, to explore how diversity, morphology and function have changed through time. Patterns are more complex than sometimes expected, with frequent decoupling of species diversity and morphological diversity, pointing to the need for some new generalizations about the processes that lie behind such patterns.
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Affiliation(s)
- Michael J Benton
- School of Earth Sciences, University of Bristol, Bristol BS8 1RJ, UK
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Fischer V, Cappetta H, Vincent P, Garcia G, Goolaerts S, Martin JE, Roggero D, Valentin X. Ichthyosaurs from the French Rhaetian indicate a severe turnover across the Triassic-Jurassic boundary. Naturwissenschaften 2014; 101:1027-40. [PMID: 25256640 DOI: 10.1007/s00114-014-1242-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Revised: 09/12/2014] [Accepted: 09/15/2014] [Indexed: 11/29/2022]
Abstract
Mesozoic marine reptiles went through a severe turnover near the end of the Triassic. Notably, an important extinction event affected ichthyosaurs, sweeping a large part of the group. This crisis is, however, obscured by an extremely poor fossil record and is regarded as protracted over the entire Norian-earliest Jurassic interval, for the lack of a more precise scenario. The iconic whale-sized shastasaurid ichthyosaurs are regarded as early victims of this turnover, disappearing by the middle Norian. Here we evaluate the pattern of this turnover among ichthyosaurs by analysing the faunal record of two Rhaetian localities. One locality is Autun, eastern France; we rediscovered in this material the holotypes or partial 'type' series of Rachitrema pellati, Actiosaurus gaudryi, Ichthyosaurus rheticus, Ichthyosaurus carinatus and Plesiosaurus bibractensis; a revised taxonomic scheme is proposed. The second assemblage comes from a new locality: Cuers, southeastern France. Both these assemblages provide several lines of evidence for the presence of shastasaurid-like ichthyosaurs in the Rhaetian of Europe. These occurrences suggest that both the demise of shastasaurids and the sudden radiation of neoichthyosaurians occurred within a short time window; this turnover appears not only more abrupt but also more complex than previously postulated and adds a new facet of the end-Triassic mass extinction.
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Affiliation(s)
- Valentin Fischer
- Geology Department, Université de Liège, B18 Allée du 6 Août, 4000, Liège, Belgium,
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Smith AJ, Rosario MV, Eiting TP, Dumont ER. Joined at the hip: linked characters and the problem of missing data in studies of disparity. Evolution 2014; 68:2386-400. [PMID: 24758277 DOI: 10.1111/evo.12435] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Accepted: 04/13/2014] [Indexed: 11/28/2022]
Abstract
Paleontological investigations into morphological diversity, or disparity, are often confronted with large amounts of missing data. We illustrate how missing discrete data affect disparity using a novel simulation for removing data based on parameters from published datasets that contain both extinct and extant taxa. We develop an algorithm that assesses the distribution of missing characters in extinct taxa, and simulates data loss by applying that distribution to extant taxa. We term this technique "linkage." We compare differences in disparity metrics and ordination spaces produced by linkage and random character removal. When we incorporated linkage among characters, disparity metrics declined and ordination spaces shrank at a slower rate with increasing missing data, indicating that correlations among characters govern the sensitivity of disparity analysis. We also present and test a new disparity method that uses the linkage algorithm to correct for the bias caused by missing data. We equalized proportions of missing data among time bins before calculating disparity, and found that estimates of disparity changed when missing data were taken into account. By removing the bias of missing data, we can gain new insights into the morphological evolution of organisms and highlight the detrimental effects of missing data on disparity analysis.
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Affiliation(s)
- Andrew J Smith
- Graduate Program in Organismic and Evolutionary Biology, University of Massachusetts Amherst, Amherst, Massachusetts 01003.
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32
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Scheyer TM, Romano C, Jenks J, Bucher H. Early Triassic marine biotic recovery: the predators' perspective. PLoS One 2014; 9:e88987. [PMID: 24647136 PMCID: PMC3960099 DOI: 10.1371/journal.pone.0088987] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Accepted: 01/13/2014] [Indexed: 11/18/2022] Open
Abstract
Examining the geological past of our planet allows us to study periods of severe climatic and biological crises and recoveries, biotic and abiotic ecosystem fluctuations, and faunal and floral turnovers through time. Furthermore, the recovery dynamics of large predators provide a key for evaluation of the pattern and tempo of ecosystem recovery because predators are interpreted to react most sensitively to environmental turbulences. The end-Permian mass extinction was the most severe crisis experienced by life on Earth, and the common paradigm persists that the biotic recovery from the extinction event was unusually slow and occurred in a step-wise manner, lasting up to eight to nine million years well into the early Middle Triassic (Anisian) in the oceans, and even longer in the terrestrial realm. Here we survey the global distribution and size spectra of Early Triassic and Anisian marine predatory vertebrates (fishes, amphibians and reptiles) to elucidate the height of trophic pyramids in the aftermath of the end-Permian event. The survey of body size was done by compiling maximum standard lengths for the bony fishes and some cartilaginous fishes, and total size (estimates) for the tetrapods. The distribution and size spectra of the latter are difficult to assess because of preservation artifacts and are thus mostly discussed qualitatively. The data nevertheless demonstrate that no significant size increase of predators is observable from the Early Triassic to the Anisian, as would be expected from the prolonged and stepwise trophic recovery model. The data further indicate that marine ecosystems characterized by multiple trophic levels existed from the earliest Early Triassic onwards. However, a major change in the taxonomic composition of predatory guilds occurred less than two million years after the end-Permian extinction event, in which a transition from fish/amphibian to fish/reptile-dominated higher trophic levels within ecosystems became apparent.
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Affiliation(s)
- Torsten M. Scheyer
- Paläontologisches Institut und Museum, Universität Zürich, Zürich, Switzerland
- * E-mail: (TMS); (CR)
| | - Carlo Romano
- Paläontologisches Institut und Museum, Universität Zürich, Zürich, Switzerland
- * E-mail: (TMS); (CR)
| | - Jim Jenks
- West Jordan, Utah, United States of America
- New Mexico Museum of Natural History and Science, Albuquerque, New Mexico, United States of America
| | - Hugo Bucher
- Paläontologisches Institut und Museum, Universität Zürich, Zürich, Switzerland
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33
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Hughes M, Gerber S, Wills MA. Clades reach highest morphological disparity early in their evolution. Proc Natl Acad Sci U S A 2013; 110:13875-9. [PMID: 23884651 PMCID: PMC3752257 DOI: 10.1073/pnas.1302642110] [Citation(s) in RCA: 126] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
There are few putative macroevolutionary trends or rules that withstand scrutiny. Here, we test and verify the purported tendency for animal clades to reach their maximum morphological variety relatively early in their evolutionary histories (early high disparity). We present a meta-analysis of 98 metazoan clades radiating throughout the Phanerozoic. The disparity profiles of groups through time are summarized in terms of their center of gravity (CG), with values above and below 0.50 indicating top- and bottom-heaviness, respectively. Clades that terminate at one of the "big five" mass extinction events tend to have truncated trajectories, with a significantly top-heavy CG distribution overall. The remaining 63 clades show the opposite tendency, with a significantly bottom-heavy mean CG (relatively early high disparity). Resampling tests are used to identify groups with a CG significantly above or below 0.50; clades not terminating at a mass extinction are three times more likely to be significantly bottom-heavy than top-heavy. Overall, there is no clear temporal trend in disparity profile shapes from the Cambrian to the Recent, and early high disparity is the predominant pattern throughout the Phanerozoic. Our results do not allow us to distinguish between ecological and developmental explanations for this phenomenon. To the extent that ecology has a role, however, the paucity of bottom-heavy clades radiating in the immediate wake of mass extinctions suggests that early high disparity more probably results from the evolution of key apomorphies at the base of clades rather than from physical drivers or catastrophic ecospace clearing.
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Affiliation(s)
- Martin Hughes
- Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, United Kingdom
| | - Sylvain Gerber
- Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, United Kingdom
| | - Matthew Albion Wills
- Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, United Kingdom
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34
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Fischer V, Appleby RM, Naish D, Liston J, Riding JB, Brindley S, Godefroit P. A basal thunnosaurian from Iraq reveals disparate phylogenetic origins for Cretaceous ichthyosaurs. Biol Lett 2013; 9:20130021. [PMID: 23676653 DOI: 10.1098/rsbl.2013.0021] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Cretaceous ichthyosaurs have typically been considered a small, homogeneous assemblage sharing a common Late Jurassic ancestor. Their low diversity and disparity have been interpreted as indicative of a decline leading to their Cenomanian extinction. We describe the first post-Triassic ichthyosaur from the Middle East, Malawania anachronus gen. et sp. nov. from the Early Cretaceous of Iraq, and re-evaluate the evolutionary history of parvipelvian ichthyosaurs via phylogenetic and cladogenesis rate analyses. Malawania represents a basal grade in thunnosaurian evolution that arose during a major Late Triassic radiation event and was previously thought to have gone extinct during the Early Jurassic. Its pectoral morphology appears surprisingly archaic, retaining a forefin architecture similar to that of its Early Jurassic relatives. After the initial latest Triassic radiation of early thunnosaurians, two subsequent large radiations produced lineages with Cretaceous representatives, but the radiation events themselves are pre-Cretaceous. Cretaceous ichthyosaurs therefore include distantly related lineages, with contrasting evolutionary histories, and appear more diverse and disparate than previously supposed.
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Affiliation(s)
- Valentin Fischer
- Paleontology Department, Royal Belgian Institute of Natural Sciences, Brussels, Belgium.
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35
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Benson RBJ, Druckenmiller PS. Faunal turnover of marine tetrapods during the Jurassic-Cretaceous transition. Biol Rev Camb Philos Soc 2013; 89:1-23. [PMID: 23581455 DOI: 10.1111/brv.12038] [Citation(s) in RCA: 150] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Revised: 02/28/2013] [Accepted: 03/06/2013] [Indexed: 11/30/2022]
Affiliation(s)
| | - Patrick S. Druckenmiller
- Department of Geology and Geophysics; University of Alaska Museum, University of Alaska Fairbanks; Fairbanks Alaska 99775, U.S.A
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36
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Toljagic O, Butler RJ. Triassic-Jurassic mass extinction as trigger for the Mesozoic radiation of crocodylomorphs. Biol Lett 2013; 9:20130095. [PMID: 23536443 DOI: 10.1098/rsbl.2013.0095] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Pseudosuchia, one of the two main clades of Archosauria (Reptilia: Diapsida), suffered a major decline in lineage diversity during the Triassic-Jurassic (TJ) mass extinction (approx. 201 Ma). Crocodylomorpha, including living crocodilians and their extinct relatives, is the only group of pseudosuchians that survived into the Jurassic. We reassess changes in pseudosuchian morphological diversity (disparity) across this time interval, using considerably larger sample sizes than in previous analyses. Our results show that metrics of pseudosuchian disparity did not change significantly across the TJ boundary, contrasting with previous work suggesting low pseudosuchian disparity in the Early Jurassic following the TJ mass extinction. However, a significant shift in morphospace occupation between Late Triassic and Early Jurassic taxa is recognized, suggesting that the TJ extinction of many pseudosuchian lineages was followed by a major and geologically rapid adaptive radiation of crocodylomorphs. This marks the onset of the spectacularly successful evolutionary history of crocodylomorphs in Jurassic and Cretaceous ecosystems.
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Affiliation(s)
- Olja Toljagic
- GeoBio-Center, Ludwig-Maximilians-Universität München, Richard-Wagner-Strasse 10, 80333 Munich, Germany.
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37
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Condamine FL, Rolland J, Morlon H. Macroevolutionary perspectives to environmental change. Ecol Lett 2013; 16 Suppl 1:72-85. [DOI: 10.1111/ele.12062] [Citation(s) in RCA: 183] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Revised: 10/10/2012] [Accepted: 12/04/2012] [Indexed: 11/28/2022]
Affiliation(s)
- Fabien L. Condamine
- CNRS; UMR 7641 Centre de Mathématiques Appliquées (École Polytechnique); Route de Saclay; 91128 Palaiseau; France
| | - Jonathan Rolland
- CNRS; UMR 7641 Centre de Mathématiques Appliquées (École Polytechnique); Route de Saclay; 91128 Palaiseau; France
| | - Hélène Morlon
- CNRS; UMR 7641 Centre de Mathématiques Appliquées (École Polytechnique); Route de Saclay; 91128 Palaiseau; France
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38
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Macropredatory ichthyosaur from the Middle Triassic and the origin of modern trophic networks. Proc Natl Acad Sci U S A 2013; 110:1393-7. [PMID: 23297200 DOI: 10.1073/pnas.1216750110] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The biotic recovery from Earth's most severe extinction event at the Permian-Triassic boundary largely reestablished the preextinction structure of marine trophic networks, with marine reptiles assuming the predator roles. However, the highest trophic level of today's marine ecosystems, i.e., macropredatory tetrapods that forage on prey of similar size to their own, was thus far lacking in the Paleozoic and early Mesozoic. Here we report a top-tier tetrapod predator, a very large (>8.6 m) ichthyosaur from the early Middle Triassic (244 Ma), of Nevada. This ichthyosaur had a massive skull and large labiolingually flattened teeth with two cutting edges indicative of a macropredatory feeding style. Its presence documents the rapid evolution of modern marine ecosystems in the Triassic where the same level of complexity as observed in today's marine ecosystems is reached within 8 My after the Permian-Triassic mass extinction and within 4 My of the time reptiles first invaded the sea. This find also indicates that the biotic recovery in the marine realm may have occurred faster compared with terrestrial ecosystems, where the first apex predators may not have evolved before the Carnian.
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39
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Benson RBJ, Evans M, Druckenmiller PS. High diversity, low disparity and small body size in plesiosaurs (Reptilia, Sauropterygia) from the Triassic-Jurassic boundary. PLoS One 2012; 7:e31838. [PMID: 22438869 PMCID: PMC3306369 DOI: 10.1371/journal.pone.0031838] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Accepted: 01/12/2012] [Indexed: 11/18/2022] Open
Abstract
Invasion of the open ocean by tetrapods represents a major evolutionary transition that occurred independently in cetaceans, mosasauroids, chelonioids (sea turtles), ichthyosaurs and plesiosaurs. Plesiosaurian reptiles invaded pelagic ocean environments immediately following the Late Triassic extinctions. This diversification is recorded by three intensively-sampled European fossil faunas, spanning 20 million years (Ma). These provide an unparalleled opportunity to document changes in key macroevolutionary parameters associated with secondary adaptation to pelagic life in tetrapods. A comprehensive assessment focuses on the oldest fauna, from the Blue Lias Formation of Street, and nearby localities, in Somerset, UK (Earliest Jurassic: 200 Ma), identifying three new species representing two small-bodied rhomaleosaurids (Stratesaurus taylori gen et sp. nov.; Avalonnectes arturi gen. et sp. nov) and the most basal plesiosauroid, Eoplesiosaurus antiquior gen. et sp. nov. The initial radiation of plesiosaurs was characterised by high, but short-lived, diversity of an archaic clade, Rhomaleosauridae. Representatives of this initial radiation were replaced by derived, neoplesiosaurian plesiosaurs at small-medium body sizes during a more gradual accumulation of morphological disparity. This gradualistic modality suggests that adaptive radiations within tetrapod subclades are not always characterised by the initially high levels of disparity observed in the Paleozoic origins of major metazoan body plans, or in the origin of tetrapods. High rhomaleosaurid diversity immediately following the Triassic-Jurassic boundary supports the gradual model of Late Triassic extinctions, mostly predating the boundary itself. Increase in both maximum and minimum body length early in plesiosaurian history suggests a driven evolutionary trend. However, Maximum-likelihood models suggest only passive expansion into higher body size categories.
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Affiliation(s)
- Roger B J Benson
- Department of Earth Sciences, University of Cambridge, Cambridge, United Kingdom.
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40
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New ophthalmosaurid ichthyosaurs from the European Lower Cretaceous demonstrate extensive ichthyosaur survival across the Jurassic-Cretaceous boundary. PLoS One 2012; 7:e29234. [PMID: 22235274 PMCID: PMC3250416 DOI: 10.1371/journal.pone.0029234] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2011] [Accepted: 11/22/2011] [Indexed: 11/19/2022] Open
Abstract
Background Ichthyosauria is a diverse clade of marine amniotes that spanned most of the Mesozoic. Until recently, most authors interpreted the fossil record as showing that three major extinction events affected this group during its history: one during the latest Triassic, one at the Jurassic–Cretaceous boundary (JCB), and one (resulting in total extinction) at the Cenomanian-Turonian boundary. The JCB was believed to eradicate most of the peculiar morphotypes found in the Late Jurassic, in favor of apparently less specialized forms in the Cretaceous. However, the record of ichthyosaurs from the Berriasian–Barremian interval is extremely limited, and the effects of the end-Jurassic extinction event on ichthyosaurs remains poorly understood. Methodology/Principal Findings Based on new material from the Hauterivian of England and Germany and on abundant material from the Cambridge Greensand Formation, we name a new ophthalmosaurid, Acamptonectes densus gen. et sp. nov. This taxon shares numerous features with Ophthalmosaurus, a genus now restricted to the Callovian–Berriasian interval. Our phylogenetic analysis indicates that Ophthalmosauridae diverged early in its history into two markedly distinct clades, Ophthalmosaurinae and Platypterygiinae, both of which cross the JCB and persist to the late Albian at least. To evaluate the effect of the JCB extinction event on ichthyosaurs, we calculated cladogenesis, extinction, and survival rates for each stage of the Oxfordian–Barremian interval, under different scenarios. The extinction rate during the JCB never surpasses the background extinction rate for the Oxfordian–Barremian interval and the JCB records one of the highest survival rates of the interval. Conclusions/Significance There is currently no evidence that ichthyosaurs were affected by the JCB extinction event, in contrast to many other marine groups. Ophthalmosaurid ichthyosaurs remained diverse from their rapid radiation in the Middle Jurassic to their total extinction at the beginning of the Late Cretaceous.
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