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New Ophthalmosaurid Ichthyosaurs from the European Lower Cretaceous Demonstrate Extensive Ichthyosaur Survival across the Jurassic–Cretaceous Boundary

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–Cret...

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Autores principales: Fischer, Valentin, Maisch, Michael W., Naish, Darren, Kosma, Ralf, Liston, Jeff, Joger, Ulrich, Krüger, Fritz J., Pérez, Judith Pardo, Tainsh, Jessica, Appleby, Robert M.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2012
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3250416/
https://www.ncbi.nlm.nih.gov/pubmed/22235274
http://dx.doi.org/10.1371/journal.pone.0029234
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author Fischer, Valentin
Maisch, Michael W.
Naish, Darren
Kosma, Ralf
Liston, Jeff
Joger, Ulrich
Krüger, Fritz J.
Pérez, Judith Pardo
Tainsh, Jessica
Appleby, Robert M.
author_facet Fischer, Valentin
Maisch, Michael W.
Naish, Darren
Kosma, Ralf
Liston, Jeff
Joger, Ulrich
Krüger, Fritz J.
Pérez, Judith Pardo
Tainsh, Jessica
Appleby, Robert M.
author_sort Fischer, Valentin
collection PubMed
description 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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spelling pubmed-32504162012-01-10 New Ophthalmosaurid Ichthyosaurs from the European Lower Cretaceous Demonstrate Extensive Ichthyosaur Survival across the Jurassic–Cretaceous Boundary Fischer, Valentin Maisch, Michael W. Naish, Darren Kosma, Ralf Liston, Jeff Joger, Ulrich Krüger, Fritz J. Pérez, Judith Pardo Tainsh, Jessica Appleby, Robert M. PLoS One Research Article 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. Public Library of Science 2012-01-03 /pmc/articles/PMC3250416/ /pubmed/22235274 http://dx.doi.org/10.1371/journal.pone.0029234 Text en Fischer et al. http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited.
spellingShingle Research Article
Fischer, Valentin
Maisch, Michael W.
Naish, Darren
Kosma, Ralf
Liston, Jeff
Joger, Ulrich
Krüger, Fritz J.
Pérez, Judith Pardo
Tainsh, Jessica
Appleby, Robert M.
New Ophthalmosaurid Ichthyosaurs from the European Lower Cretaceous Demonstrate Extensive Ichthyosaur Survival across the Jurassic–Cretaceous Boundary
title New Ophthalmosaurid Ichthyosaurs from the European Lower Cretaceous Demonstrate Extensive Ichthyosaur Survival across the Jurassic–Cretaceous Boundary
title_full New Ophthalmosaurid Ichthyosaurs from the European Lower Cretaceous Demonstrate Extensive Ichthyosaur Survival across the Jurassic–Cretaceous Boundary
title_fullStr New Ophthalmosaurid Ichthyosaurs from the European Lower Cretaceous Demonstrate Extensive Ichthyosaur Survival across the Jurassic–Cretaceous Boundary
title_full_unstemmed New Ophthalmosaurid Ichthyosaurs from the European Lower Cretaceous Demonstrate Extensive Ichthyosaur Survival across the Jurassic–Cretaceous Boundary
title_short New Ophthalmosaurid Ichthyosaurs from the European Lower Cretaceous Demonstrate Extensive Ichthyosaur Survival across the Jurassic–Cretaceous Boundary
title_sort new ophthalmosaurid ichthyosaurs from the european lower cretaceous demonstrate extensive ichthyosaur survival across the jurassic–cretaceous boundary
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3250416/
https://www.ncbi.nlm.nih.gov/pubmed/22235274
http://dx.doi.org/10.1371/journal.pone.0029234
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