Re: Triassic protofeathers and fake-heads

["David Marjanovic" <david.marjanovic@gmx.at>]

----- Original Message -----
From: "Ken Kinman" <kinman@hotmail.com>
Sent: Thursday, February 21, 2002 3:36 AM

> We see a similar sort of arms race with
> trilobites in the Paleozoic.  You don't find the most spiny trilobites in
> the Cambrian----they came later as the Paleozoic arms race escalated.

How come then that we find one of the most fearsome trilobite predators in
the Middle Cambrian -- *Anomalocaris*?

>      David's objections didn't make sense to me either.  It's the
predators
> that are doing most of the brain development.  Gazelles concentrate on
speed
> to escape, and their predators must compensate by a combination of some
> speed increase, but mostly on agility and the brainpower to harness that
> agility as the prey got faster and more agile.

Sometimes predators are dumber than all their prey, I mentioned the Komodo
monitor. Probably various fossil terrestrial crocs would also count. Not
sure about sharks.
        Jellyfish!!! Were top predators in the Cambrian and still only have
a nerve net! Comb jellies! Same! That's what winners look like!

>      There was a Mesozoic arms race just as surely as their was a Cenozoic
> arms race.

Which happens to be pretty exactly what I say :-P

> And more and more tetrapods had bigger and more complicated
> brains than their Paleozoic ancestors.  Sure brains are metabolically
> expensive, but the advantages must outweigh the costs, or we would all
still
> have simple amphibian brains.  Even if the mean hadn't gone up (and that
is
> arguable), the upper end brains have clearly been increasing in size and
> mental ability.

But hey, this is no trend. The upper end _was able to_ increase, the lower
end was _not_. Expand diversity, as will pretty inevitably happen over time,
and you get an increase of the upper end _by itself_. It just happens.
        Often no advantages outweigh the metabolic costs of a brain. That of
*Branchiostoma* is often considered reduced (though it has a limbic system
plus hypothalamus), and you know well about heaps of parasites.

>       The biggest doesn't necessarily have to be the smartest brain, but I
> certainly couldn't be communicating with you all if I had the brain of a
> therapsid, much less the brain of a Devonian amphibian.

So what?

> There are clearly
> general trends from Paleozoic to Mesozoic to Cenozoic that are so obvious,
> it puzzles me why people would want to argue against it.

Because, when you take a closer look at them, it turns out they aren't
trends at all. You concentrate on the upper end instead of looking at the
whole range, the "full house", of diversity.

> Is the word
> "progress" so politically incorrect that we have to ignore the obvious
> trends.  This just seems like an overreaction to past mistakes, and the
> pendulum gets swung too far the other way.

Who cares about political correctness. Progress as a main component of
evolution is just a falsified hypothesis.

> A Komodo dragon may be dumb
> compared to its mammalian or avian prey.  But I bet it takes more brain
> power for them to ambush their prey than for a frog to stick out its
tongue
> and catch an insect.

So what? :-) It's still dumber than all of its prey -- among which are even
pigs!