RE: Claws on deinonychosaurs

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

> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> Tim Williams
>
> Ken Carpenter wrote:
>
> >Argh! Somebody please explain to me (not done in the original
> >description by Maxwell and Ostrom) how multiple predators/scavengers on
> >a carcass suddenly fall over dead!
>
> They ate too much?
>
> Seriously... it does beg the question: if the _Deinonychus_ specimens were
> casualties of a desperate _Tenontosaurus_ fighting for its life, isn't this
> is a fairly high mortality rate for a _Deinonychus_ pack?  The species could
> not afford such losses every time a pack went after large prey.
>
> Just playing Devil's advocate.

And playing Devil's advocate to your Devil's advocate...

Dinosaurs are not placentals, and Deinonychus packs (if such existed) are not 
wolf packs. Dinosaurs would necessarily have higher
mortality rates than mammals, as they had much greater potential fecundity 
rates. That is to say, clutch size for dinosaurs are much
greater than typical litter size for mammals. (This disparity is far greater at 
larger sizes, though).

So, all things being equal, the expectation is that far more Deinonychus would 
die per clutch than would Canis or Panthera per
litter. Similarly, though, it would be easier to help maintain pack size 
(again, if such existed) even with high mortality.

All this is part of Holtz's Law of Mesozoic Terrestrial Paleoecology: In the 
Mesozoic, Life was Cheap!

                Thomas R. Holtz, Jr.
        Senior Lecturer, Vertebrate Paleontology
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
        Mailing Address:
                Building 237, Room 1117
                College Park, MD  20742

http://www.geol.umd.edu/~tholtz/
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