Re: Mesozoic mountains?

[Amtoine Grant <ajgrant@eastlink.ca>]

On Wednesday, March 2, 2005, at 11:41  AM, David Marjanovic wrote:

> > > http://jan.ucc.nau.edu/~rcb7/paleogeographic.html
> >
> > Nice link. Looking at the map of the early Cretaceous Earth, it looks
> > to me like Greenland would be a fantastic place to unearth clues on
> > spinosaur ancestry and evolution.
>
> Why?

My take on the theory that spinosaurs are derived coelophysids. I 
imagine that as the continents spread apart, namely NA & what is now 
Europe, chains of island would have periodically ascended & descended 
from the tectonic movements. My support for this comes from the fact 
that Coelophysids are found in North America[albeit dang-near 
everywhere], including here in Nova Scotia, the furthest eastward 
extension of North America. Also, the gracile build, relatively 
similiar body proportions, and kinked snouts - unless the latter trait 
evolved again in these theropods, wouldn't be the first time. If there 
indeed was a chain of periodic landmasses in the Atlantic Ocean, this 
affinity with water lends reason to the piscivorous adaptations. It 
would also explain the recently discussed purpose of the spinosaurs 
jaws being suited for small(er) prey than more robust-jawed theropods 
such as allosaurs, megalosaurs & tyrannosaurs. We all [should] know 
that when animals take up residence on islands, they tend to experience 
a reduction in body size, so to me this would make perfect sense of the 
physiology of spinosaurs, except the sail.
And no, I haven't taken into account Irritator from South America, but 
then again none of know ALL the answers. Also, if I recall, spinosaurid 
sizes go from smaller to larger starting in Europe with Baryonx, 
reaching their peak with Spinosaurus in North Africa. Almost as if the 
size restraint imposed by island-dwelling was lifted as they moved from 
my preposed North Atlantic islands to mainland. . .