|
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
|