DESOJO Julia Brenda
Reassessment of the Middle Triassic rauisuchian archosaurs Ticinosuchus ferox and Stagonosuchus nyassicus
LAUTENSCHLAGER, STEPHAN; DESOJO, J.B.
Año: 2011 p. 357 - 381
The Middle Triassic (Anisian) rauisuchianarchosaurs Ticinosuchus ferox and Stagonosuchus nyassicusare two of the earliest representatives of this group andtherefore of special importance for our understanding ofthe evolution and early diversification of Rauisuchia. Bothtaxa are well preserved and, in the case of the holotype ofTicinosuchus ferox, nearly complete and articulated.However, the original descriptions and recent revisions ofthe material do not sufficiently cover all aspects of theirosteology. We identify new skull elements previouslyunknown for Ticinosuchus ferox and present new reconstructionsof the pectoral and pelvic girdle elements. Vertebrallaminae and fossae are described for the first time inboth Ticinosuchus ferox and Stagonosuchus nyassicus.Newly recognised character states of Stagonosuchus nyassicusinclude the presence of additional infraprezygapophysealand infrapostzygapophyseal laminae in the cervicalvertebrae, a hyposphene-hypantrum articulation in thedorsal vertebrae and a fibula with a posteromedialdepression. Furthermore, we provide a revised and emendeddiagnosis for both taxa, including several autapomorphiesfor Stagonosuchus nyassicus (e.g. a boss-likeprotuberance on the postacetabular process of the iliacblade and a marked short dorsolateral crest on the proximalischium). We review the taxonomic status of a furtherspecimen of Ticinosuchus ferox, as well as material relatedto Stagonosuchus nyassicus from the Manda Beds ofTanzania. Additionally, we discuss the distribution andpossible function of rauisuchian characters, such asaccessory neural spines in the caudal vertebrae, in theseand other rauisuchian taxa.