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Eutretauranosuchus (Jurassic goniopholidid crocodylomorph) osteology

From: Ben Creisler

A new paper. Note that the open access version is not yet posted on
the AMNH site.

Adam C. Pritchard, Alan H. Turner, Eric R. Allen & Mark A. Norell (2013)
Osteology of a North American Goniopholidid (Eutretauranosuchus
delfsi) and Palate Evolution in Neosuchia no access.
American Museum Novitates Number 3783: 1-56
doi: http://dx.doi.org/10.1206/3783.2

[Not yet posted in open access:

The goniopholidid Eutretauranosuchus delfsi is currently known from
two skulls from the Late Jurassic Morrison Formation of Colorado. Here
we present a detailed osteology for a third Eutretauranosuchus delfsi
specimen (AMNH FARB 570), consisting of a skull and fragmentary
postcranium from Bone Cabin Quarry, Wyoming (Morrison Formation).
Additional preparation, computed tomography (CT), and
three-dimensional processing of CT images reveal matrix-covered
structures on AMNH FARB 570, provide new information on goniopholidid
cranial anatomy, and allow for the first description of an articulated
North American goniopholidid braincase. These new data, along with
restudy of the palatal anatomy in Eutretauranosuchus, provide valuable
insight into the phylogenetic history of goniopholidid crocodyliforms.
The skull of AMNH FARB 570 is extremely similar to other specimens of
E. delfsi and Amphicotylus spp., especially in details of the
architecture of the palate. In these Morrison Formation goniopholidids
the secondary palate is incomplete such that the nasopharyngeal
passage has no ventral floor. Additionally, there is a complex septum,
constructed from the vomers and pterygoid, which extends ventrally
near to the plane of the secondary palate. Characters diagnosing
Eutretauranosuchus delfsi include: (1) an elongate, platyrostral
skull; (2) a prominent depression on the posterolateral surface of the
alveolar process of the maxilla; (3) minimal lateral undulation of the
maxillary tooth row; (4) broad- ening of the nasals anterior to the
prefrontals; (5) nasals that do not contact external nares; (6) a
broad, flat interfenestral bar with raised rims along the
supratemporal fenestrae; (7) a nasopharyngeal septum formed from
diverging vomeral processes anteriorly and a midline pterygoid process
posteriorly (also in Amphicotylus lucasii, AMNH FARB 5782); and (8) a
vomeral septal complex that forms an X shape in cross section.

Based on a revised phylogenetic analysis of 88 crocodylomorph taxa, a
novel phylogenetic hypothesis is proposed in which a clade of
Calsoyasuchus + Sunosuchus is sister to a clade of Goniopholis
baryglyphaeus + (Goniopholis simus + (Amphicotylus lucasii +
Eutretauranosuchus delfsi)). Examination of secondary palate
characters in Goniopholididae suggests that this group “experimented”
with changes to the bony secondary palate a number of times, resulting
in morphologies not seen other mesoeucrocodylian clades.