Re: Mesozoic - the heyday of life?

[NJPharris@aol.com]

In a message dated 97-06-10 14:44:47 EDT, DSFPortree@aol.com writes:

>  ...seems to
>  me that, in many ways, life on Earth took a downturn after the Mesozoic.
>  Animals now are generally smaller. 

This is probably due more to the fact that the fossil record is biased
against smaller beasties than any general decrease in size.

> They
>  don't have as big and varied an arsenal of weaponry, offensive and
defensive
>  as did the dinosaurs.

This is probably related to two factors:  1)Many dinosaurs were (and all
surviving are) bipedal, which freed up the hands for use as weapons; and
2)Dinosaurs primitively had bony ossicles set into the skin, which could be
developed into body armor, spikes, plates, etc.


>  Mammalia
>  has never produced anything on the scale of a Brachiasaurus or
Tyrannosaurus
>  rex. 

I once submitted a very long post suggesting a number of reasons why land
mammals will probably never be as large as sauropods (mostly relating to
feeding and biomechanical considerations).  Bear in mind, too, that it took
the dinosaurs 70 million years to produce _Brachiosaurus_ and over 150
million to produce _Tyrannosaurus_, and that was without humans butting in
and screwing up the process!

BTW, what about _Balaenoptera musculus_, our old friend the blue whale, one
of the very largest vertebrates ever?

Food for thought.

Nick Pharris