RE: late night thoughts: not all T. rexes were adults

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

> From: owner-DINOSAUR@usc.edu [mailto:owner-DINOSAUR@usc.edu]On Behalf Of
> Paul P

[snip]

> What no one
> ever seems to mention (correct me if i'm wrong) is that
> *juvenile* T. rexes must have been fearsome predators.

Oh, it's been mentioned...

> One weighing in at about a ton, perhaps. Does anyone
> know what's been published on this (non-hypothetical)?
> What's the allometry of the hindlimbs?

Ummm... I hate when my work is invisible... :-S  Many references have looked at 
hindlimb proportions in tyrannosaurids (work by me
and by Currie and by Carr and by...). And yes, juvenile tyrannosaurids have 
very, very slender elongate distal limb elements.
Indeed, there is a nice overlap between the largest known ornithomimid 
hindlimbs and the juvenile tyrannosaurid limbs.

> Has anyone estim-
> ated the speed/agility of a juvenile or subadult T. rex?
>
Actually, Hutchinson (2004. J Morphology 262:441-461) addressed a small 
tyrannosaur (FMNH PR 2211) and found that it might
reasonably reach a Froude number of 17, which would come out as 11-14 m/s.

                Thomas R. Holtz, Jr.
        Senior Lecturer, Vertebrate Paleontology
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
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