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Proterochampsa (Archosauria) restudied



From: Ben Creisler
bcreisler@gmail.com


A new online paper:

DILKES, D. and ARCUCCI, A. (2012)
Proterochampsa barrionuevoi (Archosauriformes: Proterochampsia) from
the Late Triassic (Carnian) of Argentina and a phylogenetic analysis
of Proterochampsia.
Palaeontology (advance online publication)
doi: 10.1111/j.1475-4983.2012.01170.x
http://onlinelibrary.wiley.com/doi/10.1111/j.1475-4983.2012.01170.x/abstract


Restudy of skulls and available postcrania of the proterochampsian
archosauriform Proterochampsa barrionuevoi from the Ischigualasto
Formation (Upper Triassic, Carnian) in the San Juan Province,
Argentina, confirms that the genus is diagnosed by autapomorphies that
include dermal sculpturing consisting of prominent ridges and nodular
protuberances, a large hook-like lateral projection on the
quadratojugal, an antorbital fossa restricted to a depression along
the maxilla, lateral expansion of the premaxilla anterior to the
premaxilla–maxilla contact, absence of a supratemporal fossa,
exclusion of jugal from suborbital fenestra, basal tubera of
parabasisphenoid facing ventrally and reaching laterally beyond the
basipterygoid process, and a ventral lamina on the angular.
Proterochampsa nodosa is a valid species distinguished from P.
barrionuevoi by fewer cranial ridges with larger protuberances,
relatively smaller supratemporal fenestrae and width of frontals
between orbits less than that of the nasals. A phylogenetic analysis
supports the monophyly of Proterochampsia consisting of
Proterochampsa, Chanaresuchus bonapartei, Gualosuchus reigi,
Tropidosuchus romeri and Cerritosaurus binsfeldi. A temporal
separation between the two basal proterochampsians with earliest
records in the Late Triassic (Proterochampsa and Cerritosaurus) and
Chanaresuchus, Gualosuchus and Tropidosuchus in the Middle Triassic
indicates hidden proterochampsian diversity in the Middle Triassic.