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RE: Eoraptor (Triassic sauropodomorph) described

When did Eoraptor become a sauropodomorph?

-----Original Message-----
From: Ben Creisler [mailto:bcreisler@gmail.com] 
Sent: 09 October 2013 04:31
To: dinosaur@usc.edu
Subject: Eoraptor (Triassic sauropodomorph) described

From: Ben Creisler

Eoraptor paper in the new Journal of Vertebrate Paleontology Memoir:

Paul C. Sereno, Ricardo N. Martínez & Oscar A. Alcober (2013) Osteology of
Eoraptor lunensis (Dinosauria, Sauropodomorpha).
Basal sauropodomorphs and the vertebrate fossil record of the Ischigualasto
Formation (Late Triassic: Carnian-Norian) of Argentina.
Journal of Vertebrate Paleontology Memoir 12: 83-179

We describe the basal sauropodomorph Eoraptor lunensis, based on the nearly
complete holotypic skeleton and referred specimens, all of which were
discovered in the Cancha de Bochas Member of the Ischigualasto Formation in
northwestern Argentina. The lightly built skull has a slightly enlarged
external naris and a spacious antorbital fossa with a prominent, everted
dorsal margin and internal wall lacking any pneumatic extensions into
surrounding bones. The tall quadrate is lapped along its anterior margin by
the long, slender ventral process of the squamosal, and the lower jaw has a
mid-mandibular joint between a tongue-shaped splenial process and a trough
in the angular. All but the posterior-most maxillary and dentary crowns have
a basal constriction, and the marginal denticles are larger and oriented
more vertically than in typical theropod serrations. Rows of rudimentary
palatal teeth are present on the pterygoid. Vertebral centra are hollow,
although not demonstrably pneumatized, and all long bones have hollow
shafts. The radius and ulna are more robust, the manus proportionately
shorter, and the manual unguals less recurved than in the contemporaneous
basal theropod Eodromaeus murphi. An outstanding feature of the manus of
Eoraptor is the twisted shaft of the first phalanx of the pollex, which
deflects medially the tip of the ungual as in basal sauropodomorphs. The
long bones of the hind limb have more robust shafts than those of
Eodromaeus, although in both genera the tibia remains slightly longer than
the femur.