RE: Speculative dino species

["Srnka, Christopher P." <Srnka.Christopher@mayo.edu>]

Excellent points to keep in mind. But regarding the amount of change over 65
million years, in particular after the K/T event (which in the speculative
scenario did not result in dinosaur extinction but still was a major event
regardless) and through the ice age; wouldn't we expect evolution to have
punctuated the equilibrium, not to be too punny...?

> ----------
> From:         Thomas R. Holtz, Jr.
> Sent:         Friday, July 27, 2001 3:12 PM
> To:   Srnka, Christopher P.; 'Daniel Bensen'
> Cc:   dinosaur@usc.edu
> Subject:      RE: Speculative dino species
> 
> > 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
> 
>