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RE: Brooding rex? (was Feathers for T. rex)




-----Original Message-----
From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of R.
Irmis
Sent: Tuesday, February 26, 2002 4:56 PM
To: TiJaWi@agron.iastate.edu
Cc: Dinosaur Mailing List
Subject: RE: Brooding rex? (was Feathers for T. rex)

<<Cattle, sheep and horses usually have less offspring than dogs, cats and
rats.>>

This is most likely due to the fact that cattle, sheep, and horses are
larger than dogs, cats and rats, not whether they are herbivorous or not.
See:

Janis, Christine M. and Matthew Carrano. 1992. Scaling of reproductive
turnover in archosaurs and mammals: why are large terrestrial mammals so
rare?. Annales Zoologici Fennici 28(3-4): 201-216.

I disagree with this. We're talking about two different kinds of animals and
how they reproduce. Mammals are not dinosaurs and vice a versa. Animals that
have large 'broods' have high mortality rates, if they didn't we'd be
overrun with pigeons (more than we already are). Mammals and birds care and
protect their young and need only one or a few more offspring. Dinosaurs
have nests with a larger amount of eggs and only a few would survive; from
the nest to adult stage. Any maternal behavior of dinosaurs is speculative
and needs to be remembered that even though some hadrosaurs are thought to
have had parental care because of the non-fusion of limbs etc., doesn't mean
parental care like a bird or mammals, because of the large number of eggs in
each nest. Large number of eggs means high mortality rates. A nest of 12 or
more eggs would mean only 2-4 would be needed to reach adult hood to keep
the species going.
The argument about going to a chicken farm; been there done that and sneezed
my head off when I was young :( My parents would have to park the car
downwind and walk in and out with eggs. Also a chicken farm isn't a natural
occurrence, but a human one. Perhaps the better analogy would be a rookery?
But that is still only one or two eggs and not the number that dinosaur
nests have.

Regards,
Randall Irmis


Tracy L. Ford
P. O. Box 1171
Poway Ca  92074