RE: Speculative dino species

["Thomas R. Holtz, Jr." <tholtz@geol.umd.edu>]

> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> Srnka, Christopher P.
>
> A list-wide project would be nice...any other takers? Perhaps we
> could play
> out a few "what if" scenarios on a message board somewhere, so
> artwork could
> be displayed....I got on this kick after doing some sketches of what I
> thought might have been another evolutionary path for dromaeosaurids....
>
> http://www.comixmatrix.com/artists/image.asp?id=266385

A couple things to keep in mind (which Greg Paul did in his
reconstructions):

I) Consider how much change (or rather, as is often the case, how little
change) occurred within the various lineages throughout the Cretaceous.
That is, how much morphological difference is there between the ?Barremian
_Sinornithosaurus_, the Aptian-Albian _Deinonychus_, and the Campanian
_Velociraptor_ and _Bambiraptor_ (a space of 45 million years or more).

II) If the conciet is simply "the K/T mass extinction did not occur", no
cheating by having the survival of taxa we are reasonably certain WERE
extinct before the end of the Maastrichtian.  For example, no Cenozoic
centrosaurines or stegosaurians or coelophysoids.

III) Keep in mind the other secular changes in Earth's environment during
the Cretaceous: the continued plate tectonic development of the Earth; the
late Eocene extinctions and the development of the psychrosphere (and the
resetting of Earth's thermostat, phase 1); the spread of the grasslands in
South America, and later in Africa, Eurasia, and North America; the
Himalayan orogeny and resetting of Earth's thermostat, phase 2; the
developement of the Isthmus of Panama and the resetting of Earth's
thermostat, phase 3 (aka the late Cenozoic ice ages).

                Thomas R. Holtz, Jr.
                Vertebrate Paleontologist
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
                College Park, MD  20742
http://www.geol.umd.edu/~tholtz/tholtz.htm
http://www.geol.umd.edu/~jmerck/eltsite
Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661       Fax (CPS-ELT): 301-405-0796