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Re: Bitten Ornithopod on This Side Of Hell?

Dino Rampage wrote:

What interests me is how as compared to the fauna of the Judith River & Horseshoe Canyon Formations, few of the Hell Creek/Lance fauna seem to show any tendency to collect in bonebeds. It seems to me that most specimens are discovered individually rather than in huge herds (like in Pachyrhinosaurus, Maiasaura, Centrosaurus & many others I can't recall). Would this somehow reflect a different social structure or perhaps a preservational bias. Or perhaps the environment was different, so it was more useful to live a solitary life or in smaller herds.

No, I suspect the greater number of Campanian bonebeds may have been due to a generally drier climate, which may have meant more severe droughts and fewer places where dinos could congregate for their last drink before death. That may have resulted in more and larger mass accumulations of taxa than in the late Maastrichtian, when the climate was wetter.

Any comments and are there any bonebeds of
Hell Creek ceratopsians/ hadrosaurs?

I do remember there is a Torosaurus bonebed while the much more common Triceratops does not. Could it be that Triceratops were more common but lived in smaller herds. (Although it does not make sense. It seems to me that the most common grazing animals today live in large herds)

And as to anecdotal evidence that Triceratops was more common in Hell Creek than Edmontosaurus, could it be because Triceratops preferred the habitat of Hell Creek rather than the Lance Formation?

Possible, but IIRC the CO track record suggests Triceratops was common farther south.

What habitats are preserved in these two formations and did they differ in climate or precipitation?

There seems to be a taphonomic bias against complete T. rex skeletons in the Lance while Edmontosaurus is known from better material.

----Original Message Follows---- From: "Tim Donovan" <msdonovan66@hotmail.com> Reply-To: msdonovan66@hotmail.com To: Danvarner@aol.com, dinosaur@usc.edu Subject: Re: Bitten Ornithopod on This Side Of Hell? Date: Sun, 30 Mar 2003 07:14:28 -0500

Danvarner wrote:

       I would really hesitate to say that. To my knowledge, there are no
accurate databases to support that statement. Or are there?

Apparently for a long time. See Lehman's Late Maastrichtian Paleoenvironments and Dinosaur Biogeography in the Western Interior of North America. Fig 8 indicates a drop in the relative abundance of Triceratops and an increase in Edmontosaurus from Hell Creek to Lance. Admittedly that's an old ref but I note Horner's recent work in the Hell Creek yielded considerably more Triceratops specimens than edmontosaurs.

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