Parvipelvia; Baracromia; Malawania anachronus; Early Cretaceous
Abstract :
[en] 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.
Disciplines :
Earth sciences & physical geography
Author, co-author :
Fischer, Valentin ; Université de Liège - ULiège > Département de géologie > Paléontologie animale et humaine
Appleby, Robert
Naish, Darren
Liston, Jeff
Riding, James
Brindley, Stephen
Godefroit, Pascal
Language :
English
Title :
A basal thunnosaurian from Iraq reveals disparate phylogenetic origins for Cretaceous ichthyosaurs
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