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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(1):e29234.Plos

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.

Authors+Show Affiliations

Geology Department, University of Liège, Liège, Belgium. v.fischer@ulg.ac.beNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

22235274

Citation

Fischer, Valentin, et al. "New Ophthalmosaurid Ichthyosaurs From the European Lower Cretaceous Demonstrate Extensive Ichthyosaur Survival Across the Jurassic-Cretaceous Boundary." PloS One, vol. 7, no. 1, 2012, pp. e29234.
Fischer V, Maisch MW, Naish D, et al. New ophthalmosaurid ichthyosaurs from the European Lower Cretaceous demonstrate extensive ichthyosaur survival across the Jurassic-Cretaceous boundary. PLoS One. 2012;7(1):e29234.
Fischer, V., Maisch, M. W., Naish, D., Kosma, R., Liston, J., Joger, U., Krüger, F. J., Pérez, J. P., Tainsh, J., & Appleby, R. M. (2012). New ophthalmosaurid ichthyosaurs from the European Lower Cretaceous demonstrate extensive ichthyosaur survival across the Jurassic-Cretaceous boundary. PloS One, 7(1), e29234. https://doi.org/10.1371/journal.pone.0029234
Fischer V, et al. New Ophthalmosaurid Ichthyosaurs From the European Lower Cretaceous Demonstrate Extensive Ichthyosaur Survival Across the Jurassic-Cretaceous Boundary. PLoS One. 2012;7(1):e29234. PubMed PMID: 22235274.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - New ophthalmosaurid ichthyosaurs from the European Lower Cretaceous demonstrate extensive ichthyosaur survival across the Jurassic-Cretaceous boundary. AU - Fischer,Valentin, AU - Maisch,Michael W, AU - Naish,Darren, AU - Kosma,Ralf, AU - Liston,Jeff, AU - Joger,Ulrich, AU - Krüger,Fritz J, AU - Pérez,Judith Pardo, AU - Tainsh,Jessica, AU - Appleby,Robert M, Y1 - 2012/01/03/ PY - 2011/10/06/received PY - 2011/11/22/accepted PY - 2012/1/12/entrez PY - 2012/1/12/pubmed PY - 2012/5/15/medline SP - e29234 EP - e29234 JF - PloS one JO - PLoS One VL - 7 IS - 1 N2 - 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. SN - 1932-6203 UR - https://www.unboundmedicine.com/medline/citation/22235274/New_ophthalmosaurid_ichthyosaurs_from_the_European_Lower_Cretaceous_demonstrate_extensive_ichthyosaur_survival_across_the_Jurassic_Cretaceous_boundary_ L2 - https://dx.plos.org/10.1371/journal.pone.0029234 DB - PRIME DP - Unbound Medicine ER -