Re: Fossilization

Harry Erwin (herwin@gmu.edu)
Sun, 30 Jul 1995 17:22:05 -0400

In article <60.2368.7295.0N1ED6F0@canrem.com>, j#d#.moore@canrem.com (J.
Moore) wrote:

> NE>Do you think gorillas and chimps haven't evolved in 5 - 10 Myr? Your
> NE>question makes it apparent that you think we evolved from creatures
> NE>identical to modern gorillas or chimps. We do not have a fossil record
> NE>for gorillas and chimps, and thus are denied much information from those
> NE>branches of the hominoid evolutionary tree.
>
> An> Why not? Why don't we have a fossil record for gorillas or chimps?
> An> Ann
>
> The answer is almost certainly habitat. If, as seems likely, they
> lived in forests like they do now, well, that's a horrible place to
> be if you want to end up fossilized. ;-) Problem is you rot, and
> little bugs and whatnot eat you, and you don't get covered up by
> sediment or volcanic ash, which are topnotch ways to get
> fossilized. Animals which spend a great deal of time in, for instance,
> mud flats or shallow water get fossilized at one hell of a rate.
> That's why there's so many fossil pigs in Africa that they can be
> used to check dating processes, as I mentioned in a post on the
> Dating of 1470.

Since the posited 'aquatic ape' was no more than a 'wading ape' (otherwise
it would have had markedly shortened, robust legs, shortened, robust arms,
streamlining, dorsalized eyes and nose, and a good deal less joint laxness
than we see in Australopithecus/Homo), this implies that it should have
been fossilized at a high rate in sediments of the appropriate date and
location. In other words, the aquatic ape is a lot more testable than the
jungle or savannah ape. The only ape we do see from those environments so
far seems to be Oreopithecus, though, which was highly arboreal and not
very close to hominid ancestry. Of course, it was likely to have been
bipedal on the ground, like Hylobates or Ateles.

>
> This effect of environment of the likelihood of fossilization
> would seem to be why we find more hominid fossils than fossils of
> proto-chimps and proto-gorillas. It also would seem to be why
> you don't find as many hominid fossils as you do pigs.
>
> Jim Moore (j#d#.moore@canrem.com)
>
> * Q-Blue 2.0 *

-- 

Harry Erwin

Internet: herwin@gmu.edu

Home Page: http://osf1.gmu.edu/~herwin (try again if necessary)

PhD student in comp neurosci: "Glitches happen" & "Meaning is emotional"