Re: Lack of Running Giant Theropod Tracks

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

On Mon, Nov 29th, 2010 at 8:50 PM, Mike Taylor <mike@indexdata.com> wrote:

> Do we know of any extant animals in which the juveniles can run faster
> than the adults?  While no doubt there must be a way exceptions (sea
> squirts? :-)), I think they ARE exceptions.  I'm not convinced by the
> widespread a priori assumption that adult ceratopsians and
> tyrannosaurs were slower than the juveniles.

I don't know about 'faster', but baby rhinos certainly run 'more often' than 
their parents. In fact it 
seems that young rhinos only have two speeds - a flat-out run, and asleep. :-)

Perhaps the issue isn't about speed, but rather endurance?

Also; the bigger you get, the more you become inertia's and momentum's biatch. 
A large adult 
tyrannosaur would need to overcome a lot more inertia to get to a fast run, and 
then have to 
counteract a lot more momentum to come to a safe stop again. Juveniles could 
likely accelerate 
and decelerate more quickly.

If tyrannosaurs didn't hunt in groups, then perhaps there was a major change in 
hunting strategy 
as they got older - from prolonged agile chases as juveniles to primarily 
ambush predator at larger 
sizes (or scavenger, or kill-stealer).

If they did hunt in groups, then having younger and more agile members do the 
chasing, and 
larger members waiting in ambush, might have been a better strategy that played 
to everyone's 
strengths.

> I'm not getting into the bit of the argument; I'll just state for the
> record that I think Don in GROSSLY overstating the vulnerability of
> sauropods, and move on.

I can envisage how a boy scout could kill a sauropod. It involves the sauropod 
swallowing said boy 
scout whole, and subsequently choking to death.

-- 
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Dann Pigdon
Spatial Data Analyst               Australian Dinosaurs
Melbourne, Australia               http://home.alphalink.com.au/~dannj
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