Re: Extinction and other...

[Matt Wedel <sauropod@ou.edu>]

> ah but don't look at humans, WE didn't survive the KT....our ancestor
65
> million years ago did.  WE are derived.

Ah, but I didn't.  I was using 'we' in the very inclusive, "all hairy
things"
sense.  There was no way for you to know that, unless you had picked up
a book to
see if Cretaceous mammals had pineal foramina in their skulls.  They
didn't.
Mammals proper, including those that survived the KT boundary, all have
their
pineal glands roofed over by skull and brains.  The last thing in our
line that
had a pineal foramen was a Permian or Triassic synapsid.  And neither
birds nor
crocs have pineal foramina, so the pineal gland as an evolutionarily
retained
structure seems to be doing fine without a window of its own.

> Unless the earth's been knocked off it's orbit to screw up the
seasons,
> and out of normal rotation to screw up day/night, these periods would
> not have changed.

An "asteroid winter" would, by definition, screw up the seasons.  And my
point was
that if the light only varied from near dusk to pitch black, that might
not be
enough light to keep circadian rhythms from running smoothly.  This is
my
speculation, and I freely admit that I may be mistaken.  But in terms of
pineal
foramina, dinos, mammals, birds, and crocs are all lacking (the foramen,
not the
gland), so I see no correlation between the gland and KT extinctions.

Matt Wedel