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Re: Dinosaur gastralia and their function in respiration



In a message dated 95-11-28 00:43:51 EST, dtanke@dns.magtech.ab.ca (D. Tanke)
writes (actually, Leon Claessens writes):

> Gastralia are present in theropods, in prosauropods and in primitive
>ornithischians. 

Don't forget sauropods. See the paper on _Apatosaurus yahnahpin_ by Filla &
Redman in the 1994 Wyoming Geological Association Guidebook. Dan Chure has
_Camarasaurus_ gastralia in situ on the cliff face at Dinosaur National
Monument. They are slender and whiplike (I saw them myself in 1993).

For what it's worth, I'm certain the presence of gastralia is plesiomorphic
for Dinosauria; but I don't know how far back this feature goes in
Archosauria or Diapsida. Are the heavy plesiosaur gastralia homologous to
dinosaur gastralia, for example, or did they arise independently?

Also, watch out for the first abdominal rib in theropods: It may be a
furcula.