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Re: Triassic protofeathers and fake-heads
----- Original Message -----
From: "Ken Kinman" <firstname.lastname@example.org>
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
> that are doing most of the brain development. Gazelles concentrate on
> 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
> have simple amphibian brains. Even if the mean hadn't gone up (and that
> 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.
> 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
> and catch an insect.
So what? :-) It's still dumber than all of its prey -- among which are even