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Re: Triceratops sprawl
On Fri, 2 Feb 1996, Rob Meyerson wrote:
> These are reasonable objections. However, I point out that the big=
> ceratopians first appear in North America. According to my theory,=
> protoceratopids evolve in the sands of the Gobi with the features I have=
> mentioned that make them a very successful animal. When they migrate to=
> North America, the "dune buggy" design, which gives them an immense=
> stability (definately an advantage) on the "stable" land surface, which=
> helps them to be an extremely successful group. This success is marked by=
> an increase in size.
There's no proof that protoceratopsids as a group evolved in
the deserts of Mongolia. All we know is that a couple branches of the
marginocephalian family tree- Protoceratops and Psittacosaurus- show up
there, which proves only that Protoceratops and Psittacosaurus lived in
Mongolia. Their ancestors could have lived anywhere in asia, and probably
did live all across asia, the only thing special about Mongolia is that it
has the right conditions for these animals to show up. Their ancestors
could have evolved in any number of places besides dunes.
If a future
paleontologist found skeletons of a jackrabbit, a spadefoot toad, a
tortoise and a coyote in desert sediments, could they then conclude that
lagomorphs, anapsids, anurans and canids all evolved in desert
conditions? Or if this future paleontologist found fossils of ground
sloths in florida, and mammoths in south america, could they justifiably
conclude that these were the ancestral homelands of the group?
Not to mention the fact that Cretaceous North America is not
noted for sand dunes (I suppose Pachyrhinosaurus went dune-busting up on
the North Slope?), the fact that putting the limbs out to the side is
competely contradictory to the trackway evidence, and that animals like
camels get along just fine with long, erect limbs.