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Re: Trialestes, dino? croc? or proud parent to both?



Dave Peters (davidrpeters@earthlink.net) wrote:

<That's what I like to see. Corroborating evidence. Would love to see some pix.
Thanks for the reference Tim!>

  I don't have access to this at the moment, but I would contend against the
post's subject line, since it is assuming the nature of the features without
understanding the fossil or its application. Then again, I've read most, if not
all, of the papers in Clark et al.s bibliography on the subject, and the group
to which *Trialestes* is referred or suggested in referral to is dear to me.

  In this case, you get a particularly elongated forelimb with elongated
carpals, a perforated acetabulum, and the vertically arranged hindlimb. These
are not at odds with a crocodylian, especially one associated with a
particularly fascinating group such as the "Sphenosuchia." Note that there are
grades of this group, which may be cladistically defined, or simply left as is
until more material is found. Crocs like *Dibrothosuchus*, *Hesperosuchus*,
*Psuedhesperosuchus*, and *Terrestrisuchus* are all particularly gangly-limbed,
terrestrial, "running" crocs, and all of them show pelvic, femoral, scapular,
and forelimb adaptations for cursoriality, a topic I may eventually become able
to address in detail. These crocs are also well-nested within Crurotarsi, and
in fact Crocodylomorpha as well, and the likelihood they are ancestral to
anything pterosaurian and/or dinosaurian is remote to unlikely, and dare I say,
even improbable.

  Clark et al. are understandably cautious in their referrals, though they do
not approach the topic of speculating heavily, with good reason, the
crocodilian nature of all three fossils and they're belonging to the same
taxon. They may well all belong to different crocs, and maybe there's a
"silesaurid" or some such in there. Yet they may belong to a similar group of
taxa, but may bear distinct names. Hopefully time and more interesting recovery
periods in the fossil horizons will provide new and interesting -- and
hopefully, clarifying! -- data.

  Cheers,

Jaime A. Headden
http://bitestuff.blogspot.com/

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)


       
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