Re: Tyrannosaur allometry paper in CJES

[Dann Pigdon <dannj@alphalink.com.au>]

"Thomas R. Holtz, Jr." wrote:
> >
> > Also, Currie has redone Russell's (1970) attempt to determine the
> > proportions of a 1.5 m long hatchling tyrannosaur, using the new allometric
> > curves.  Some of the proportions are similar to those proposed by Russell,
> > but others are considerably different.  I would be interested in seeing an
> > artist using these data to reconstruct a baby tyrannosaur.
>

I've roughed up a quick image according to Currie's extrapolations,
which can be seen at:
http://www.alphalink.com.au/~dannj/temp/rexhatchling.gif

It differs quite a bit from my original guesstimate, except that the
forelimb proportions are pretty much exactly as I predicted (I know, I'm
scared too). I chose not to make the lower limbs twice as long as the
femur, since it was clear (as Currie points out) that something was
amiss with the figures calculated for the tibia and metatarsals.

Could this indicate that tyrannosaur hind limb proportions changed
little for many years, only robusting-up when the tyrannosaurs reached
mammoth proportions? This might indicate that fully mature adults were
not as speedy as their younger counterparts (or perhaps that, once a
certain size is reached, there is a sort of biometric paradigm shift
where running ability and limb proportions are concerned).

Russell's original estimates had a hatchling of 1.5m in length with a
femur of 10cm. My reconstuction turns out at about 0.85m (just shy of
three feet) in length for the same femoral length. Still pretty big for
a newly hatched animal though. Could the tail have been even longer than
I suspect (or the neck for that matter)? Exactly how would a 1.5m baby
fit in a 50cm long egg anyway?

-- 
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Dann Pigdon                   Australian Dinosaurs:
GIS / Archaeologist         http://www.geocities.com/dannsdinosaurs
Melbourne, Australia        http://www.alphalink.com.au/~dannj/
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