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Re: More about Erickson et al. 2004



Thomas Holtz wrote-

> > I thought AMNH 5428, AMNH 5432 and USNM 12814 were Gorgosaurus, not
> > Albertosaurus.
>
> Good catch (although AMNH 5428 and USNM 12814 are the same specimen:
> transferred from the AMNH to the USNM in (I believe) the Barosaurus deal).
> The AMNH retains some of the gastralia, and maybe some other elements;
most
> of the body is on display on the wall at the USNM.
>
> The net result is the transfer of two points to the Gorgo curve from the
> nearly identical Alberto curve, making the former more secure but the
latter
> less so.
>
> As for why neither the authors nor any of the reviewers didn't catch this,
> the simple explanation is... um... hey, look at that over there!!!  What's
> that behind you? [hoping to distract people]

Haha.  Thanks for the info on the specimens' identical nature.  The
photographed material left over of AMNH 5428 seems to be mostly dorsal rib
fragments from what I can tell.
http://paleo.amnh.org/fossil/img_show.html?file=http://paleo.amnh.org/i/5428
-01.jpg

And might I note that my services are always available to get unpublished
information ahead of ti... er... review theropod papers to ensure errors
like this don't make it into press.

> If the selection of specimens used here actually represented a variety of
> adults and subadults of tyrannosaurines of different sizes, it is
remarkable
> that they fall on a single nice logistic curve rather than (as would be
> predicted) a series of curves of different slopes during the exponential
> growth phase.

Well, I was picturing the three pairs of close-sized specimens as three
potential taxa (rex - FMNH PR2081 + RTMP 81.12.1; RTMP 81.6.1 + ICM
2001.90.1; megagracilis - LACM 23845 + AMNH 30564), with LACM 28471 being a
juvenile of any of them.  Then one could hypothesize a more gradual growth
rate for all three, which would match the more basal tyrannosaurids and fit
each pair of points a bit better.
Not that I'm advocating this at all, I just thought the growth data
entertained this possibility.

> -Also, these help reinforce the idea of determinate growth in at least
many
> dinosaur clades.

Which I didn't think existed prior to this paper (shows how closely I follow
the histological literature).

Mickey Mortimer
Undergraduate, Earth and Space Sciences
University of Washington
The Theropod Database - http://students.washington.edu/eoraptor/Home.html