A basal thunnosaurian from Iraq reveals disparate phylogenetic origins for Cretaceous ichthyosaurs

Fischer, Valentin; Appleby, Robert M.; Naish, Darren; Liston, Jeff; Riding, James B. ORCID: https://orcid.org/0000-0002-5529-8989; Brindley, Stephen; Godefroit, Pascal. 2013 A basal thunnosaurian from Iraq reveals disparate phylogenetic origins for Cretaceous ichthyosaurs. Biology Letters, 9 (4), 20130021. https://doi.org/10.1098/rsbl.2013.0021

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Official URL: http://dx.doi.org/10.1098/rsbl.2013.0021

Abstract/Summary

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.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.1098/rsbl.2013.0021
ISSN:	1744-9561
Date made live:	15 May 2013 14:10 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/501935

Item Type:

Publication - Article

Digital Object Identifier (DOI):

https://doi.org/10.1098/rsbl.2013.0021

ISSN:

1744-9561

Date made live:

15 May 2013 14:10 +0 (UTC)

URI:

https://nora.nerc.ac.uk/id/eprint/501935