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Re: Nanotyrannus

>Having seen the Nannotyrannus skull at the Cleveland museum, it is apparent
>to me that it is not a juvenile. The skull is quite small but seems to have
>adult features: a long maxilla that seems to be proportional in size to that
>of an adult Tyrannosaur, instead of the foreshortened and flattened feature
>that one finds on many dinosaur juveniles. Its teeth are also proportional in
>size to an adult. All bone seems to be fully ossified, as well.

Unfortunately, most of the "juvenile" characters you've described here are
not juvenile for theropods.  Theropod maxillae, for example, become
proportionately shorter with age compared to the rest of the skull.  The
teeth of a probable juvenile Gorgosaurus libratus (the type specimen of
Gorgosaurus "sternbergi") are not only proportionately, but also
absolutely, larger than those of adult specimens.

Incidentally, I am not advocating that the type of Nanotyrannus is
definitely a juvenile T. rex.  In fact, I'm on paper as referring to it as
a probably valid taxon.  However, I was pointing out to the people on the
net that the case has not been definitely made as to the adult status of
this individual, despite the original descriptions as such in Bakker et al.

Thomas R. Holtz, Jr.                                   
Vertebrate Paleontologist in Exile                  Phone:      703-648-5280
U.S. Geological Survey                                FAX:      703-648-5420
Branch of Paleontology & Stratigraphy
MS 970 National Center
Reston, VA  22092