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Susisuchidae (Crocodyliformes) phylogenetic placement in Neosuchia (free pdf)

Ben Creisler

A new paper:

Alan H. Turner & Adam C. Pritchard (2015)
The monophyly of Susisuchidae (Crocodyliformes) and its phylogenetic
placement in Neosuchia.
PeerJ 3:e759
doi: http://dx.doi.org/10.7717/peerj.759

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.