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Re: attack on dinosaur--horrific video




----- Original Message ----- From: "David Marjanovic" <david.marjanovic@gmx.at>
To: "DML" <dinosaur@usc.edu>
Sent: Saturday, November 24, 2007 5:30 PM
Subject: Re: attack on dinosaur--horrific video




Then we should see a driven trend to larger size throughout the Mesozoic, shouldn't we?

No..there are trade offs. Many dinosaurs were pretty big, though.

Because... it's somewhat disingenuous to refer to my still unpublished M.Sc. thesis, the dataset of which needs to be expanded and the methods of which need to be drastically improved... but I don't see such a trend so far.

I remember it was thought not too long ago that end K dinosaurs were the largest of their particular clades (e.g., _T. rex_). Your data doesn't show this?


Is vivipary any good for protection from predators? The marsupial method seems to be better for than than the placental one. If a gravid wildebeest is chased by a lion, mother and fetus die.

To quote good old documentaries: predation is mainly on the young, sick and old. Due to an amazing system of connective tissue supports, a fetus has virtually no impact on a mother's ability to run away--except at the very end, of course. I used to have a reference stating that predation was very rare on pregnant animals. Do you have one to the contrary?


If a kangaroo with a pouch young is chased by a dingo, the joey dies alone, because of that special muscle in the pouch...

Amazing...the mother coughs up the joey? What is that muscle?

while the waiting embryo resumes development, resulting in a net loss of nothing but a few weeks or months. As an r-strategy, placental reproduction sucks bigtime.

Truly an amazing aspect of marsupial reproduction. But the whole point--teleologically-speaking--of placental reproduction is investment--that a few gifted offspring are better able to move more genes into more future offspring than r strategist, albeit r strategists flood the reproductive scene with many disposable units.