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Re: Albertosaurine Survival and the End of the Cretaceous



I have very little understanding of what you guys are talking about but I am so 
facinated by the last couple million years of the Mesozoic in North America I 
would be interested in knowing anything and everything on this era. What 
animals have we found from this time? Where were they located? 
 

Andrew Simpson

--- On Tue, 6/24/08, Raptorial Talon <raptorialtalon@gmail.com> wrote:

> From: Raptorial Talon <raptorialtalon@gmail.com>
> Subject: Re: Albertosaurine Survival and the End of the Cretaceous
> To: DINOSAUR@usc.edu
> Date: Tuesday, June 24, 2008, 7:25 PM
> On Mon, Jun 23, 2008 at 6:31 PM, John Scanlon
> <riversleigh@outbackatisa.com.au> wrote:
> 
> "Hi Raptorial (if I may use first names),"
> 
> Heh heh, just a run-of-the-mill internet moniker. Use
> whatever variant
> you like - all I know is that "Raptorial" has
> four more letters than
> "Talon." But it's your fingers. ; )
> 
> "I hope you get some informed responses as well as
> encouraging ones; I'm no
> dinosaur expert but I already find this a more interesting
> discussion than
> the long-running origin-of-flight sideshow. (Cretaceous
> North-American
> biogeography has got somewhat interesting since fossil
> snakes started
> turning up in the Cenomanian, but I still know little about
> it).
> Cheers,
> John"
> 
> Thank you for that, and now I'm going to go brush up on
> fossil snakes.
> 
> On Tue, Jun 24, 2008 at 6:52 AM, Tim Donovan
> <uwrk2@yahoo.com> wrote:
> 
> " A few comments: Tyrannosaurus rex lived in swampy
> habitat toward the
> end, as there was a local transgression."
> 
> Interesting, interesting . . . sort of what I recalled
> hearing
> regarding *Edmontosaurus*. Good to know.
> 
> "But there is no evidence of an
> albertosaur/lambeosaur/centrosaurine/nodosaur
> comeback."
> 
> Well, of course, aside from my whole notion ultimately
> being
> conjecture, I didn't actually say anything about a
> "comeback." What I
> was really getting at was more along the lines of *refugia*
> - that the
> albertosaurine complex became *restricted* to coastal
> and/or cooler,
> higher-latitude regions while the tyrannosaurine complex
> expanded and
> became fully dominant in former albertosaurine territory.
> That is to
> say, my concept here is that inadequate sampling in the
> east, or in
> northern Canada/Alaska, may be the reason we have not yet
> found
> late-Maastrichtian albertosaurines - rather than a true,
> flat-out
> absence over all of North America. So that's what
> I'm trying to get
> clarified/confirmed/denied.
> 
> Although, as you stated, tyrannosaurines lived in swampy
> areas to the
> exlcusion of albertosaurines in the latest Cretaceous
> American
> northwest, so now any discussion would be about more
> northerly
> latitudes as the conjectural refugium. Has any
> tyrannosaurine material
> ever been reported from Alaska, and how certain are we that
> the
> Alaskan albertosaurine material really is exactly that?
> 
> "As for Asia, the late Maastrichtian age of the
> lambeosaur dominated
> Udurchukan, proposed by Goedefroit et al on the basis of
> palynomorphs,
> is not certain."
> 
> Hm, interesting once again; any papers out there that
> explain why such
> a date is uncertain? I'm assuming that some sort of
> plant-migration
> thing (the plant groups of late Maastrichtian America being
> present at
> an earlier time in Asia) is involved . . . or not. *shrugs*
> 
> "IMO the transition from Albertosaurus to T. rex
> reflected
> continent-wide, predator-prey escalation not changing
> topography."
> 
> Well, I can say that this would make sense in and of itself
> (certainly
> can't ignore that kind of competitor), but the
> simultaneous loss of
> the centrosaurines, nodosaurs, and most/all lambeosaurs
> suggests that
> some wider ecological effect was in play - some effect to
> which *T.
> rex* was probably responding via increased body size, just
> like what
> seems to have happened with *Edmontosaurus* and
> *Triceratops*, as
> additional examples. I had been under the impression that
> the
> regression of the Western Interior Seaway and the resulting
> drier/less-stable continental interior was to blame, but I
> guess it
> must have been more complex than just that.
> 
> "best,
> 
> Tim"
> 
> Thanks for the response - some good food for thought there.