RE: ornithomimosaur

["Nicholas R Longrich" <longrich@alumni.princeton.edu>]

"Tracy L. Ford" wrote
> -----Original Message-----
> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> Allan Turner
> Sent: Monday, July 01, 2002 7:44 PM
> To: aspidel@wanadoo.be; dinosaur@usc.edu
> Subject: Re: ornithomimosaur
> 
> It's Ornithomimus edmontonensis from the Dinosaur Park Formation. It was
> collected by Philip Currie, Clive Coy, Evan Fritz, Don Henderson, Ken
> Kucher, and Stewart Wright after being discovered by Jean Thompson and Kevin
> Aulenback on the morning of July 12, 1995.

        The label in the museum has it as "Ornithomimus sp." if I recall. The 
first
metacarpal is pretty long, as long or longer than MC II, which is an apomorphy
of this thing and _edmontonicus_ and a few other NA ostrich dinos; it isn't seen
in Asian ostrich dinosaurs or _Struthiomimus_. So its pretty safe to assume its
related to _edmontonicus_.

        However, _edmontonicus_ is from a more recent formation, so does it 
really
represent the same species as the DPP animal? I've been told that the Canadian
ceratopsians (for which we have a lot of material to compare, and flamboyant
interspecific variation to identify species by) are restricted to a formation-
change formation, change ceratopsian, e.g. Styracosaurus isn't found outside of
Dinosaur Park Formation. At least for some groups, turnover is very high in the
Late K of NA, it may be that ostrich dinosaurs were the same.
 
        Looking at modern biodiversity, it just seems logical that in the 
Cretaceous of
North America there might have been multiple species of ostrich dinosaur at any
given time, with species turning over every few million years. A hundred species
of ostrich dinosaur over the span of the Late Cretaceous of NA makes more sense
to me, given modern biodiversity patterns, than two or three... if you assume
that the group spanned the ~60 million years of the Cretaceous, with turnover
every 3 million years, and 50 species present worldwide at any given time then
the whole group might have had 1000 species (give or take a power of ten). 1000
species isn't a ridiculous number if you consider that there are something like
48 extant species of deer, 137 bovids, 54 of 'roos (I'm citing the U Mich
website here). Who knows tho.