Sauropods (was: Iguanodontidae and Theropod Boredom)

[Darryl Jones <dinoguy@sympatico.ca>]

At 12:03 AM 7/2/2001, qilongia@yahoo.com wrote:
>   And is there anyway we can have a thread on sauropods that
> doesn't involve some historical they were landwalkers-not-swimmers idea or
> anything about their necks... :)

I know that this doesn't seem very scientific, but I am bothered by the
amount of diversity of such large creatures.  For example, the Morrison
Formation (which I realize covers about 10 million years, but still) has
Apatosaurus, Barosaurus, Diplodocus, Brachiosaurus, Haplocanthosaurus,
Supersaurus, Camarasaurus, and Seismosaurus at very minimum.  There are
others named (Amphicoelias for example, which is probably not
distinguishable from Diplodocus) and others that are not yet described (a
primitive diplodocid described as Amphicoelias sp. at the SVP meeting in
New York?).  These are just the genera.  When you start adding in species,
the number of sauropods in the Morrison Formation starts topping 18 or
so.  How is this possible?  These were massive creatures that must have
required an enormous amount of sustenance.  Either they were extremely
successful as organisms (sauropods that is) or we have far too many named.

I do think that there was a good diversity of these Morrison
sauropods.  There are often a minimum of 4 genera in given quarries.  Were
sauropods more prone to specific variation?  Was the Morrison Formation a
perfect place and time for sauropods (although sauropod finds in China lead
me to believe that this was not the case)?  Is there more of a progression
along the Morrison that I am not seeing that has no more than 3 or 4 genera
present at any given point in time?

This actually applies to more than just sauropods in the Morrison.  There
is the same incredible diversity in stegosaurs (with at least four species
present) and (sorry) theropods (with at least 8 genera).  With this in
mind, I wondered if there were not a land bridge formed at some point
during this period that allowed a MAJOR migration of animals from, say,
Africa that would have placed many more genera and species into one place
than would normally develop on their own.



Darryl Jones  <dinoguy@sympatico.ca>

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