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Rauisuchians Ticinosuchus and Stagonosuchus redescribed



From: Ben Creisler
bh480@scn.org

Another new paper on ?rauisuchians?:

Stephan Lautenschlager and Julia Brenda Desojo (2011)
Reassessment of the Middle Triassic rauisuchian archosaurs Ticinosuchus
ferox and Stagonosuchus nyassicus. 
Paläontologische Zeitschrift 
DOI: 10.1007/s12542-011-0105-1  Online First? 

http://www.springerlink.com/content/ck762418u571474v/

Abstract 
The Middle Triassic (Anisian) rauisuchian archosaurs Ticinosuchus ferox and
Stagonosuchus nyassicus are two of the earliest representatives of this
group and therefore of special importance for our understanding of the
evolution and early diversification of Rauisuchia. Both taxa are well
preserved and, in the case of the holotype of Ticinosuchus ferox, nearly
complete and articulated. However, the original descriptions and recent
revisions of the material do not sufficiently cover all aspects of their
osteology. We identify new skull elements previously unknown for
Ticinosuchus ferox and present new reconstructions of the pectoral and
pelvic girdle elements. Vertebral laminae and fossae are described for the
first time in both Ticinosuchus ferox and Stagonosuchus nyassicus. Newly
recognised character states of Stagonosuchus nyassicus include the presence
of additional infraprezygapophyseal and infrapostzygapophyseal laminae in
the cervical vertebrae, a hyposphene-hypantrum articulation in the dorsal
vertebrae and a fibula with a posteromedial depression. Furthermore, we
provide a revised and emended diagnosis for both taxa, including several
autapomorphies for Stagonosuchus nyassicus (e.g. a boss-like protuberance
on the postacetabular process of the iliac blade and a marked short
dorsolateral crest on the proximal ischium). We review the taxonomic status
of a further specimen of Ticinosuchus ferox, as well as material related to
Stagonosuchus nyassicus from the Manda Beds of Tanzania. Additionally, we
discuss the distribution and possible function of rauisuchian characters,
such as accessory neural spines in the caudal vertebrae, in these and other
rauisuchian taxa. 


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