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Details on Teyuwasu



This will be a short one.  I'll get more of these segments posted after I get my old hard drive functioning this weekend.  But, as for Teyuwasu....
 
Teyuwasu Kischlat 1999
T. barberenai Kischlat 1999
Etymology- "Barberena's big lizard", from Tupi te'yu meaning lizard, and wa'su meaning big.  Dr. M.C. Barberena is a South American paleontologist.
Carnian, Late Triassic
Santa Maria Formation, Brazil
holotype- (Munchen Universitat, 1933L 53-54) femur, tibia
Diagnosis- two parallel ridges running proximodistally on proximal femur.
Description-
The bones are slightly distorted and come from a "robust" dinosaur.  They were originally doubtfully referred to Hoplitosuchus, which is apparently an aetosaur whose holotype is two osteoderms.
The femur lacks a trochanteric shelf, having two parallel ridges proximodistally.
The tibia has a cnemial crest (as defined by Novas, 1996) and a helicoidal rounded distal articular surface that resembles Marasuchus and Herrerasaurus.  The distal process is developed to the point that the ascending proces of the astragalus is encompassed.
Relationships-
First of all, I'm not sure this is a valid taxon.  I seem to recall that if a taxon is named after a certain year, it must be illustrated to be valid.  If it is not, it's a nomen nudum.  Also, there is no real diagnosis.  I may be wrong about that rule though, as I haven't read the ICZN.
The description is extremely short and doesn't really allow much of a phylogenetic analysis.  The trochanteric shelf is absent in non-dinosauriforms, post-Saturnalia sauropodomorphs, ornithischians (except Heterodontosaurus), Guaibasaurus, gracile "ceratosaurs" and tetanuraens.  Thus, it does not tell us much about the phylogenetic relationships of this species.  The cnemial crest is a dinosauriform synapomorphy.  The statement "the distal process is so developed as to encompass the ascending process of (the) astragalus" reminds me of the condition in coelophysoids.  In this group, the tibia descends to partially overlap the ascending process anteriorly.  I'm unsure of the condition in other "ceratosaurs".  On this very tenuous basis, I would suggest that Teyuwasu is certainly a dinosauriform and possibly a gracile-morph coelophysoid.  Further analysis would require examination of the figures in Huene (1938, 1942) or personal communication with the describer.  I can probably get Huene 1938, but if anyone has the 1942 paper, I would appreciate it if they could send me the section on Hoplitosuchus.
Reference-
Huene, 1938. Jahrbuch für Mineralogie, Geologie und Paläontologie. 147.
Huene, 1942. Die fossilen Reptilien des sudamerikanischen Gondwanalandes. Ergebnisse der Sauriergrabungen in Sudbrasilien 1928/29. Munich: Beck'sche Verlegbuchhandlung, viii, 332 pages.
Kischlat, 1999. A new dinosaurian "rescued" from the Brazilian Triassic: Teyuwasu barbarenai, new taxon. Paleontologia em Destaque, Boletim Informativo da Sociedade Brasileira de Paleontologia 14(26) 58.
 
As I said, there are no illustrations.  Oh well.  I have way too many taxa to potentially do "Details on..." segments about and far too little time in the day.
 
Mickey Mortimer