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Plateosaurid-like sauropodomorph from Upper Triassic of Brazil



From: Ben Creisler
bcreisler@gmail.com

A new online paper:


Bittencourt, J.S., Leal, L.A., Langer, M.C. & Azevedo, S.A.K. (2012)
An additional basal sauropodomorph specimen from the Upper Triassic
Caturrita Formation, southern Brazil, with comments on the
biogeography of plateosaurids.
Alcheringa (1–10).(advance online paper)
(ISSN0311-5518).
DOI:10.1080/03115518.2012.634111
http://www.tandfonline.com/doi/abs/10.1080/03115518.2012.634111



We describe an additional saurischian specimen from the Caturrita
Formation (Norian) of the Parana Basin, southern Brazil. This material
was collected in the 1950s and remained unstudied due to its
fragmentary condition. Detailed comparisons with other saurischians
worldwide reveal that some characters of the ilium, including the low
ventral projection of the medial wall of the acetabulum and its
concave ventral margin, together with the short triangular shape of
the pre-acetabular process and its mound-like dorsocaudal edge,
resemble those of sauropodomorphs such as Plateosaurus and
Riojasaurus. This set of traits suggests that MN 1326-V has affinities
with basal Sauropodomorpha, probably closer to plateosaurians than to
Saturnalia-like taxa. Previous records of this clade in the Caturrita
Formation include Unaysaurus, which has been related to Plateosaurus
within Plateosauridae. Alternative schemes suggest that plateosaurids
include Plateosaurus plus the Argentinean ‘prosauropods’
Coloradisaurus and Riojasaurus. Both hypotheses raise biogeographic
questions, as a close relationship between faunas from South America
and Europe excluding Africa and North America is not supported by
geological and biostratigraphical evidence. Additionally, the absence
of plateosaurids in other continents suggests that the geographical
distribution of this taxon is inconsistent with the geological history
of western Pangaea, and this demands further investigations of the
phylogeny of sauropodomorphs or improved sampling.