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Re: Triceratops sprawl



>There is a rather sizable hole in your argument:  big neoceratopians (the=
=20
>ones that are supposed to sprawl) don't show up in dune sediments!
>
>The numerous land connections between Asia and western North America that=
=20
>occurred near the end of the Cretaceous (Dinogeorge notwithstanding) mean=
=20
>that they certainly *could* have spread back into Asia.  After all,=20
>protoceratopids of Asian mold show up in latest Cretaceous North=20
>America.  Apparently the big ceratopids *disliked* the dry dune=20
>conditions prevalent in east Asia.

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.

Their evolution continued here in North America.  To illustrate this, If one=
 takes a skeleton of _Protoceratops_, and compares it to _Triceratops_ (both=
 drawn to appear that they were the same size), one sees that P-tops is=
 built to be more sturdy, while T-tops is built more lightly.  I suggest=
 that the neoceratopians sacrificed some of their dune busting design, while=
 keeping the advantageous portions (the basic forelimb design, for example).=
  This simply meant that they "couldn't go home again."

>I also have trouble seeing how sprawling forelimbs make for a very=20
>effective "dune busting" mode of locomotion.

Take a look at a dune buggy sometime.  The similarity in forms between the=
 ceratopian forlimb system and a dune buggy front axle assembly are=
 remarkably the same.

Rob

***
Q.  What fossil fish is a blood relative?

A.  The antiarch.