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Re: Triassic Sauropods
Matt Bonnan wrote:
titanosaurid-like femoral morphology would make me lean towards a
titanosaurid interpretation, or at least something in the
As far as this material being an example of an early titanosaur from the
Late Triassic or Early Jurassic, I would have my doubts.
Just a clarification: the term I used was "titanosauriform".
Titanosauriformes = Brachiosauridae + Titanosauria. If the sauropod
material from the Isalo Group of Madagascar belings to some type of
brachiosaurid (or at least shows "brachiosaurid" features") then it is
probably basal titanosauriform.
As Mickey Mortimer
pointed out, the locality of the _Isanosaurus_ is not from the Isalo
Formation in Madagascar but in Thailand instead. This means the date for
the Isalo Formation is probably not Late Triassic.
Actually, I was not referring at all to _Isanosaurus_ from Thailand. I was
referring to the Isalo Group of Madagascar. (No, I'm not confusing the
A Late Triassic age for the Isalo Group is given in :
Flynn, J.J. et al. (1999). A Triassic fauna from Madagascar, including
early dinosaurs. Science 286 (5440): 763-765.
Abstract: "The discovery of a Middle to Late Triassic (apprx 225 to 230
million years old) terrestrial vertebrate fauna from Madagascar is reported.
This fauna documents a temporal interval not well represented by continental
vertebrate assemblages elsewhere in the world. It contains two new
prosauropod dinosaurs, representing some of the earliest dinosaur
occurrences known globally. This assemblage provides information about the
poorly understood transition to the dinosaur-dominated faunas."
_Lapparentosaurus_ and "_Bothriospondylus_" are not from the same site that
yielded the "new prosauropods" (Isalo II, given as Middle Triassic), but
from a slightly younger site, which may correspond to latest Triassic.
I would like to see more complete material before drawing an "early
titanosaur" conclusion for _Bothriospondylus_ and _Lapparentosaurus_.
Early *titanosaur* is probably out of the question, to be sure. But early
*titanosauriform* is more in line with what Argentine researchers have
suggested for _Lapparentosaurus_.
Timothy J. Williams
Iowa State University
Ames IA 50014
Phone: 515 294 9233
Fax: 515 294 3163
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