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RE: [long]Re: How Did Hadrosaurs (and this thread) Survive?




From: "Chew Sze Lun, Kevin" <kevin@pathology.hku.hk>
Reply-To: kevin@pathology.hku.hk
To: "'rob@dinodomain.com'" <rob@dinodomain.com>, Dinosaur.Mailing.List@listproc.usc.edu
Subject: RE: [long]Re: How Did Hadrosaurs (and this thread) Survive?
Date: Wed, 30 Oct 2002 16:14:22 +0800




> -----Original Message-----
> From: Rob Gay [mailto:rob@dinodomain.com]
> Sent: Wednesday, October 30, 2002 1:37 PM
> To: Dinosaur Mailing List
> Subject: [long]Re: How Did Hadrosaurs (and this thread) Survive?
[deleted]
> Albertosaurus:   1.08    .65
> Tarbosaurus:     1.16    .71
> T. rex:               1.27    .756
> There appears to be a general trend here towards the shortening of the
> lower
> leg, but the ratio still appears to be pretty healthy. But what else
> appears
> in the data? Well, when we look at the ratio of T. rex, and then look at
> the
> ratios of our "speediest" hadrosaurs, we see that Corythosaurus has a
> _better_ ratio than Tyrannosaurus, and one equal to that of Tarbosaurus,
> and
> Parasaurolophus is almost equal (within .03) to Tyrannosaurus. So how
> could
> T. rex bring about the extinction of animals that would have been
> (theoretically) faster it!? These animals, along with the #3 speedster,

An adult kangaroo runs faster than a kangaroo rat. An adult ostrich runs
faster than a baby ostrich or a chicken. You cannot merely look at the
ratios which measure things in a relative scale and come up with some
serious conclusions concerning the speeds of different animals. An ant
can pick up an object about 50 times of its own weight, while an average
human can lift up an object no more than 3 times of his own weight. Yet,
it doesn't mean that the ant can lift up objects heavier than we can. You
can't see an ant picking up a computer can u?

At the absolute scale, T. rex has the longest limbs among all
tyrannosaurs and this is something u need to take into consideration.
Longer limbs mean a stride length, and I dun think T. rex was slower
than any hadrosaur listed in ur original message.

The same applies to Edmontosaurus. In addition to its more gracile build, its limbs were 10% longer than those of other hadrosaurs which it outlasted alongside T. rex. Again, if larger size and longer limbs conferred no advantage such as faster speed, why were these taxa selected for at the expense of others? Especially unarmed Edmontosaurus, which almost certainly fled and therefore, unlike ceratopsids, generally derived no fighting advantage from greater size.





> Maiasaura, were surviving alongside the putative Flash Gordon of the
> tyrannosaurid world, Albertosaurus, which was no doubt much faster than
> any
> of the top 3. But then we have things like Edmontosaurus, with a ponderous
> .92 ratio...and yet we're supposed to buy that it outran the lambeosaurs
> that would have been quicker than T. rex, and thus drove them to
> extinction?


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