Re: Armadillos at the K/T!

[John Bois <jbois@umd5.umd.edu>]

On Mon, 1 Oct 2001, David Marjanovic wrote:

Bois said:
> > > > Species that couldn't cope are gone!
> > >
> > > So why don't we see progress in evolution?
> >
> > Greater computational power in most vertebrates relative to Triassic
> > species.
> 
> Most vertebrates, you say? What about the 23,000 known recent species of
> "fish" (or are these just "bony fish"?), the (some thousands... 4000?)
> species of amphibians and the 6500 (IIRC) species of "reptiles"? Sure, there
> are almost 10,000 species of birds left, but that doesn't topple the
> average.

Yes, of course.  How about species with much greater computational power
exist today--in terms of computational power, this is progress.

> > Reproductive security and specialized nutritional
> > structures in mammals vs. "stem reptiles".
> 
> Nothing of that sort in most other amniotes. BTW, we don't know when mammals
> gave up laying and shelling eggs.

There is a greater diversity of reproductive techniques today than in the
Triassic--including marsupial, and placental strategies.

> > Ability to engage specialized
> > vectors to carry your sperm in flowering plants.
> 
> Even among flowering plants large groups (e. g. grasses, lots of trees) have
> reversed to engaging wind. I am allergic against several sorts of angiosperm
> pollen.

Among flowering plants, options are greater for pollination--they can use
vectors or wind, they can and have established intimate and complex
symbioses with an enormous range of assistants.  This is an increase in
complexity and diversity of reproductive techniques, which, in the
official court of progress, counts.

> > Independence from water in plants and animals.
> 
> To varying degrees in whatever-you-mean-by-plants, not counting several
> reversals, and not at all in lots of animals (even there with reversals).

No.  Animals and plants today enjoy a greater range of habitats relative
to Cambrian times.  The ability to colonize land is, I'm told, seen as
_very_ progressive in the court of progress.


> 
> > I mean, I could go on forever.  From which planet
> > must a visitor come that doesn't see these as progressions of a
> > kind?  The eye.  Birds' wings. etc., etc.
> 
> Yes, the range of complexity or whatever covered by
> organisms has increased, but there is no progress when you closely look at
> it.

Of course "progress" only has meaning to humans.  I am happy to accept
your words: the range of complexity covered by organisms has increased...
And now, paraphrasing our original argument: species that can't cope with
the range of complexity are gone.  

>         You have limited yourself to vertebrates. So you can unconciously
> overlook most life -- most of which is microscopic, and on the whole devoid
> of progress.

Whatever you want to call it, when organisms started to live symbiotically
and create the first eukaryotic cells, this was a great leap forward in
increasing complexity.