RE: Hell Creek and stegosaurs

["Williams, Tim" <TiJaWi@agron.iastate.edu>]

Rob Gay wrote:

> I'd consider this unlikely at best. There were probably maniraptorans
> running around in the Morison (_Koparion_ and its ilk)\, if not earlier,
> and they seemed to do alright then...

True - and Mickey Mortimer pointed out several sites where dromies (or
dromie-like) theropods co-existed with stegosaurs.  But I was specifically
referring to medium- to large-sized dromies (_Deinonychus_-sized or larger),
which would be able to handle a 4m+ stegosaur with ease - especially if pack
hunting.  

_Phaedrolosaurus_ may be double _Deinonychus_ in size, but its overall
morphology is poorly known (only a tooth & scrappy hindlimb bones have been
assigned to the genus).  It's not even clear if (a) the type material comes
from the same beastie (the material was found unassociated) and (b) if any
of the material is dromaeosaurid (though the tooth likely is).  The Morrison
teeth described by Britt (1991) also come unattached to a body AFAIK.

I know the above dromies-drove-steggies-to-extinction scenario is overly
simplistic, and is certainly based primarily on speculation (e.g. dromie
hunting techniques, including pack-hunting, were especially potent against
stegosaurs).  However, I've heard this idea elsewhere (though I can't
pinpoint who or when) and I thought it worth raising.

P.S. My email account got fried this morning, and most of my messages from
yesterday were lost - so apologies if I'm repeating something somebody else
has said.



Tim


-----------------------------------------------------------

Timothy J. Williams, Ph.D.

USDA-ARS Researcher
Agronomy Hall
Iowa State University
Ames IA 50014

Phone: 515 294 9233
Fax:   515 294 9359