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Overosaurus, new titanosaurian sauropod from Late Cretaceous of Argentina



From: Ben Creisler
bcreisler@gmail.com


A new sauropod in Zootaxa:

Rodolfo A. Coria, Leonardo S. Filippi, Luis M. Chiappe, Rodolfo García
& Andrea B. Arcucci (2013)
Overosaurus paradasorum gen. et sp. nov. , a new sauropod dinosaur
(Titanosauria: Lithostrotia) from the Late Cretaceous of Neuquén,
Patagonia, Argentina.
Zootaxa 3683 (4): 357–376
doi: http://dx.doi.org/10.11646/zootaxa.3683.4.2
Preview first page:
http://www.mapress.com/zootaxa/2013/f/z03683p376f.pdf

A new lithostrotian sauropod, the small-sized Overosaurus paradasorum
n. gen et sp. from the Anacleto Formation (Campanian, Late Cretaceous,
Neuquén Group, Patagonia, Argentina) is here described. The specimen
(MAU-Pv-CO-439) consists of a fully articulated vertebral series from
the 10th cervical to the 20th caudal vertebra, the last cervical ribs,
several dorsal ribs in articulation with their respective vertebrae,
the complete right ilium and fragments of the left ilium. Overosaurus
paradasorum is diagnosed by a unique combination of characters that
includes (1) posterior cervical vertebrae with long pre- and
postzygapophyses that project beyond the anterior and posterior
borders of the centrum, respectively, (2) postspinal lamina absent in
all dorsal neural spines, (3) wide and massive 9th and 10th caudal
centra that are slightly excavated laterally and have relatively flat
ventral surfaces, (4) laminar projection on the posterior border of
the second and third dorsal rib, (5) ilium proportionally shorter
anteroposteriorly and taller dorsoventrally than in other
lithostrotians, and (6) the preacetabular process of the ilium
strongly deflected laterally and with a ventrolaterally tapering end.
Analysis of the phylogenetic relationships of Overosaurus places it
within the Aeolosaurini, as the sister taxon of a monophyletic  group
formed by Aeolosaurusrionegrinus, A. maximus, Gondwanatitan faustoi
and Pitekunsaurus macayai. Overosaurus is a new representative of a
highly diversified assemblage of Campanian lithostrotians from
Patagonia that includes both Aeolosaurini and saltasaurids (e.g.
Saltasaurus, Neuquensaurus)—this small new taxon falls within the low
end of the  size spectrum represented by these Late Cretaceous
sauropods.