Re: attack on dinosaur--horrific video

[john bois <jbois@verizon.net>]

----- 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 it's somewhat disingenuous to refer to my still unpublished 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.