Re: Dissecting the Aquatic Ape: Bipedalism
HARRY R. ERWIN (herwin@osf1.gmu.edu)
4 Aug 1996 13:44:53 GMT
Paul Crowley (Paul@crowleyp.demon.co.uk) wrote:
: In article <4tsul4$t0f@portal.gmu.edu>
: herwin@mason2.gmu.edu "HARRY R. ERWIN" writes:
: > : I suggest that a serious re-examination of this "niche" would reduce
: > : or eliminate its plausibility. There would definitely have been
: > : niches for a larger bodied terrestrial apes or cercopithecoids (the
: > : current chimp/baboon) able to climb, feed, hunt and sleep in the
: > : trees; there would have been niches for smaller almost entirely
: > : arboreal primates. But one in between . . . ?
: >
: > Dryopithecus laietanus, Sivapithecus indicus,
: Niche unknown - in both cases.
For D. laiet., rhino and turtle, but no other vertebrates at that level.
I will have some time this afternoon (as I chase readings on bat biosonar)
to see if the recent journals have anything.
: > Pongo (and ancestors, which were widely distributed in eastern Asia).
: Pongo's niche is high up in the closed canopy.
Pongids are widely distributed in the SE Asia fossil record from the
Pliocene on. High up in the closed canopy doesn't survive fossilization.
: As I see it: either you have smaller easily climable trees (an
: open canopy?) which can provide food and shelter to a primarily
: territorial animal OR you have large trees not readily climable
: from the ground (closed canopy) where you get pongo, the gibbons,
: and many species of monkey. I don't see a niche in between.
I'll check.
: The ground-based animals (e.g. proto-baboons or quasi-chimps)
: will occupy virtually all the space right up to the closed canopy.
: In fact, they may well penetrate it to get to islands of climbable
: fruiting trees.
: Your purported ape is primarily arboreal but regularly climbs down
: one tree and crosses ground to climb up another one. But if there
: are ground-based animals in the area they will also be able to
: climb up and down such trees. Attempts by the arboreal ape to use
: those trees will be defeated, except in temporary "islands" in the
: heart of the closed canopy. Attempts by the arboreal ape to become
: adjusted to the ground will be defeated by the species that are
: already there. It will constantly be driven back into its own niche
: in the high canopy. It has no advantages over them, and there are
: enormous impediments in the way of any progress towards speciation
: into a new ground-based niche.
: > This is particularly the case if a significant proportion
: > of your preferred food resources are close to the ground, as the thick
: > enamel of early hominids suggests.
: >
: > The dentition of early hominids is consistent with a more ground-based
: > diet than that of modern African apes, including a significant proportion
: > of rougher food items and less leaves.
: This might be a slight change of topic and could be in another
: thread, but what you say indicates that early hominids were more
: ground-based than chimps, which spend 90% or their time on the
: ground. How about 98% for early hominids?
: What sort of food do you think it might have been? It has to be
: something more attractive than, and superior to, the fruit+nuts+
: buds+leaves+honey diet of standard mosaic forest dweller -- or else
: the speciation would not have happened. Grubbing for small seeds
: is hardly an attractive option.
: You can guess my inclinations. Someone should introduce chimps to
: shellfish and see how they cope. In addition to using stones they
: might also have to use their teeth to open or crush shells, or they
: might have to consume many fragmented pieces of shell which could
: damage their thin enamel. How do you eat a cockle if you don't
: have a pin? The maintenance of thick enamel throughout hominid
: evolution indicates the persistence of much the same diet.
: Paul.
--
Harry Erwin, Internet: herwin@gmu.edu, Web Page: http://osf1.gmu.edu/~herwin
49 year old PhD student in computational neuroscience ("how bats do it" 8)
and lecturer for CS 211 (data structures and advanced C++)
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