Re: Hadrosaur defense.

[Jonathon Woolf <jwoolf@erinet.com>]

Michael wrote:
 
> Do we know the top speed of hadrosaurs.  Whatever it was it was
> likely to be a little less than their main predator.  

If they used speed as a defense, this is true.  If they didn't use speed
as a defense -- that is, if there was no selective pressure for speed --
they probably weren't very fast at all.  I have trouble picturing a
hadrosaur moving faster than maybe 30kph, but then I have trouble
picturing a rhino with its heavy body and short legs at 40kph, and
rhinos have been clocked at around 40kph.  So who knows?

> Herding is an effecient mechanism.  It's more difficult to sneak up
> on a herd.  It's easier to not select one individual to kill in a
> running herd.  Buffalo run lions off at times.  Zebra and topi run
> hyena off.

All true, but OTOH most mammal predators are smaller than their prey. 
T-rex was rather larger than any hapless hadrosaur it might have run
across. <g>

> Your imagination is as good and important as mine.  But they had to
> have at least some defense mechanisms or they would have quickly gone
> the way of the dinosaur.  Oops!<g>

;-)  Indeed.

Here's another thought for you: maybe those vertical processes on some
hadrosaurs' vertebrae served to make a "phony backbone."  T-rex being
bigger than its prey, it was well-positioned to bite down onto the
spinal column, crushing it and crippling the prey.  There's at least one
edmontosaur somewhere that has a huge rex-size bite taken out of its
dorsal spines.  Maybe the vertical spines were there so that T-rex could
be fooled into not biting deep enough, giving the hadrosaur a chance to
escape.

-- JSW