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Re: Mesozoic mountains?
On Wednesday, March 2, 2005, at 11:41 AM, David Marjanovic wrote:
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.
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. . .