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RE: juveniles faster than adults.



 These analogies are fine and all as a starting point, but it starts to fall 
into fallacy territory when they are being applied to something quite different 
in size and morphology. Just because a species of lizard produces young that 
are faster than the adults, doesn't mean the same would apply to any dinosaur. 
There may be scaling issues that may render all these comparisons mostly 
useless. It may be similar to making the argument that a series of square rocks 
must have been created by an ancient civilization rather than natural forces 
simply because we see geometric shapes in stone buildings; such an argument 
ignores the fact that natural causes have not been ruled out. There could be 
some species that have young that are faster, some that do not, it's not that 
relevant to dinosaurs unless they have similar morphologies and size ranges. It 
would be much more productive to look at what effect the laws of physics have 
on individual morphologies of various animals. I'm sure many animals have 
several ways of compensating for the effects of the square/cube law in various 
degrees, but I think it should also be remembered that this has its limit and 
that giant dinosaurs (such as T. rex) may have been pushing it; the same goes 
for sauropods. 
 
Sim     

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> Date: Tue, 30 Nov 2010 16:23:01 -0800
> From: pristichampsus@yahoo.com
> To: dinosaur@usc.edu
> Subject: Re: Fwd: juveniles faster than adults.
>
> I fail to see why a sprawling gait should invalidate komodo monitors, or any 
> other lizards from a question about the speed of juveniles vs adults in the 
> tetrapod world.
>
> We just had an example of this occurrence in wolves, which are quadrupedal 
> mammals that get most of their hind limb thrust from the pulley-like gluteal 
> muscles (esp gluteus medius). This is very very different from how theropods 
> (or any dinosaur) moved.
>
> We should not be so quick to dismiss comparing dinosaurs to other reptiles, 
> especially when the alternative is to compare them to a group of animals they 
> haven't shared a common ancestor with in over 235 million years.
>
> And since we are on the subject I would also like to submit gharials to the 
> list of animals with faster young. Not only are juveniles faster (on land at 
> least, making the relevance questionable) but they can also lift their bodies 
> off the ground; something adult gharials are incapable of doing.
>
> Jason
>
> --- On Tue, 11/30/10, Dann Pigdon wrote:
>
> > From: Dann Pigdon 
> > Subject: Re: Fwd: juveniles faster than adults.
> > To: dinosaur@usc.edu
> > Date: Tuesday, November 30, 2010, 6:54 PM
> > I would also add Komodo monitors to
> > the list. Juveniles need to be faster in order to avoid
> > becoming a meal for an adult. However their sprawling gait
> > probably doesn't make them very good
> > analogues for theropods.
> >
> > --
> > _____________________________________________________________
> >
> > Dann Pigdon
> > Spatial Data Analyst
> > Australian Dinosaurs
> > Melbourne, Australia
> > http://home.alphalink.com.au/~dannj
> > _____________________________________________________________
> >
> >
>
>
>