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Re: Lack of Running Giant Theropod Tracks



On 30 November 2010 16:58, Erik Boehm <erikboehm07@yahoo.com> wrote:
>  It certainly is plausible that adult forms were considerably more bulky than 
> the juveniles, and thus slower, and this would be more likely if they relied 
> on size and not speed to survive as adults.

Plausible, yes.  But I'm still interested in the question I asked a
day or two ago: does anyone know ANY extant tetrapod in which the
juveniles can run faster than the adults?  I can't think of any --
which of course doesn't mean there aren't any, hence the question.

If we can't, between us, come up with counter-examples, then I think
we'd need to say the most likely explanation is that evolution
optimises for adult speed rather than juvenile speed, and that in the
absence of actual evidence to the contrary, the same was likely true
of those other tetrapods, tje dinosaurs -- tyrannosaurs and sauropods
included.

(One of the recurring lessons for me over that past few years has been
that "what makes sense" doesn't always correspond well with "what
animals actually do" -- as in, for example, the matter of habitual
neck posture.)