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Eoraptor (Triassic sauropodomorph) described



From: Ben Creisler
bcreisler@gmail.com

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
DOI:10.1080/02724634.2013.820113
http://www.tandfonline.com/doi/full/10.1080/02724634.2013.820113#.UlTBxFB6YYE

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.