The monophyly of Susisuchidae (Crocodyliformes) and its phylogenetic placement in Neosuchia

Eusuchian crocodyliforms, which include all living crocodylians, have historically been characterized by two anatomical specializations: a ball-in-socket vertebral joint and an extensive secondary hard palate with a pterygoid-bound internal choana. The Early Cretaceous neosuchian clade Susisuchidae...

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Bibliographic Details
Published in:PeerJ (San Francisco, CA) CA), 2015-02, Vol.3, p.e759-e759
Main Authors: Turner, Alan H, Pritchard, Adam C
Format: Article
Language:English
Subjects:
Biogeography
Cretaceous
Crocodylia
Crocodyliformes
Crocodylomorpha
Evolution
Evolutionary Studies
Fossils
Mesoeucrocodylia
Morphology
Museums
Neosuchia
Palate
Paleontology
Phylogenetics
Phylogeny
Systematics
Vertebrae
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Summary:Eusuchian crocodyliforms, which include all living crocodylians, have historically been characterized by two anatomical specializations: a ball-in-socket vertebral joint and an extensive secondary hard palate with a pterygoid-bound internal choana. The Early Cretaceous neosuchian clade Susisuchidae is typically regarded as phylogenetically near Eusuchia. The putative susisuchid Isisfordia duncani was initially described as a transitional form exhibiting incipient versions of these eusuchian traits. Here we examine aspects of the morphology of Isisfordia and comment on the morphology of its putative sister taxon Susisuchus. Our reexamination supports the notion of Isisfordia possessing transitional vertebral morphology but we present a new interpretation of its palate construction that shows it to be more plesiomorphic than previously thought. The secondary choana of Isisfordia is not pterygoid bound. Instead, long palatines expand distally lapping under the pterygoid to form the anterior border of the choana as is common among many advanced neosuchians. Incorporation of these observations into an expanded phylogenetic dataset of neosuchian crocodyliforms results in a new phylogenetic hypothesis for Susisuchidae. Isisfordia and Susisuchus form a monophyletic Susisuchidae that sits near the base of Neosuchia, and is not the sister taxon of Eusuchia.
ISSN:2167-8359
2167-8359
DOI:10.7717/peerj.759