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Re: Novel invasion of dino-haven by K/T mammals.



On Sun, 21 Apr 1996, Rob Meyerson wrote:
> Oy vey!!!!
>
> Okay, where do I begin.  First of all, in comparing brainsize and body
> weight between Late Cretaceous Mammals and Dinosaurs, while there may be an
> *overall* tendancy for the mammals to score higher, that is not the case
> when individual genera are compaired.  In the case of Troodon, it had more
> brainpower than any other terrestrial animal at the time (for both dinos
> and mammals).  If anything, the increase in mammal brain size at the end of
> the Cretaceous is more likely due to activity of animals like Troodon.

Thank you, Troodon.  Perhaps the quality is more important than the
quantity of neurons.
Denied light, the mammals diencephalon ballooned around the olfactory
area of the brain.  What part of Troodon's brain ballooned?  Also, a
possibility is that social behavior was adaptive--animals who are
subjected to long harsh periods of predation tend to develop social
adaptations.  Look at ants, bees.  Naked mole rats even have a kind of
queen bee, a female who is the only breeder in the colony.  Sociality,
particularly kin-selection leads to altruistic behaviors such as warning,
food sharing and communal defence.>
> Also, mammal vision is notoriously poor; only the primates have full color
> vision, where the majority of predators have limited color vision.

Whoops!

> Finally, unless you are going to suggest army ant-style swarming for the
> Cretaceous mammals, the idea of mammals being of any kind of threat to a
> several ton dinosaur is difficult to grasp.  Even if the threat was aimed
> at the eggs, there wouldn't be enough mammals around to disrupt
> survival-to-hatching rates enough to be of any threat.

Mammals, and perhaps birds too, caused a summation of egg _and_ juvenile
predation to the point whre there were more dying than being born.  And
so say all of us!