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Re: Metatarsal fusion/nonfusion: birds/theropods



At 04:12 PM 3/18/97 GMT+1000, Tim Williams wrote:
>
>>  3. All theropod dinosaurs have unfused metatarsals (except Elmisaurids
>> which do fuse their metatarsals on the proximal end only and CERATOSAURUS,
>> which does not count here as the type specimen is pathologic).
>
>What about the abelisaurids?  I could be way off track here, but 
>don't big'uns like _Carnotaurus_ and _Xenotarsosaurus_ show some 
>degree of fusion of their lower hindlimb elements into a 
>tibiotarsus and/or tarsometatarsus?  

They do have tibiotarsi (or at least some distal fusion of the tibia and
fibula).  The metatarsus is, alas, unknown for any abelisaurid so far
described.  Syntarsus, of course, does the same thing with its ankle (hence
the name...).

A side note: do any of the newer specimens of Ceratosaurus have metatarsi?
(A general call to those who have seen the specimens!). If so, do they show
fusion or not?  I do wonder if the type really is pathological, or if this
is another case of Pachyrhinosaurus-itis (a weird bony growth found in a
single specimen may be pathological; one found in ALL the specimens of that
taxon almost certainly isn't...).

Thomas R. Holtz, Jr.
Vertebrate Paleontologist     Webpage: http://www.geol.umd.edu
Dept. of Geology              Email:th81@umail.umd.edu
University of Maryland        Phone:301-405-4084
College Park, MD  20742       Fax:  301-314-9661