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Re: Quo vadis, T. rex? [long]
In a message dated 96-02-07 18:12:37 EST, you write:
> I wasn't referring to endothermy, I was refering to the argument that
>insulation wasn't needed because the Mesozoic was so much warmer. It that
>was the case, wouldn't a legitimate question then be "why didn't the mammals
>lose their hair?"
Oops! Sorry about that! But the answer to your next question would be yes; if
you were comparing apples and oranges. They are as different as reptiles and
mammals and having fur is a strict mammalian tratit
> BUT.... absence of evidence IS circumstantial evidence. Regardless,
>absence of evidence is only compelling, as far as I'm concerned, if there
>can be a strong case made that skin/feather/hair impressions should be as
>common as the growing grass.
I see where you are oming from but your premise is virtually impossible to
prove and more likely never be proven based on the viscissitudes of
preservation. But despite my skepticism I am keeping an open mind.
> There is very little evidence for arboreal and upland dinosaurs. Should
>we therefore conclude that there were no arboreal dinosaurs and no upland
>dinosaurs, rather than take into account the odds of their fossilization and
>come to a different conclusion?
True. But this is a result of the _lack_of_ preserved upland sediments. In
fact, by their very definition, uplands deposit very little sediment (not
counting lakes or streams within them). I am facing this problem right now
in the Arundel Formation. It seems that there is a nodosaur called Priconodon
crassus that is known in this unit ONLY by teeth. (Some) Nodosaurs are
believed to be upland dwellers yet the Arundel is a _lowland_ fluvial
sedimentary complex. The logical conclusion is that these teeth were washed
downdtream along with the detritus from the Appalachian and Piedmont
provinces. But why only teeth? An alternative explanation is that these are
local fossils of some other critter which may be in our posession but is so
fragmented that no one has pieced together yet.
The good thing about paleontology is that yes we can draw parallels to modern
environments and ecosystems but in most cases there will never be a
conclusive answer. The only thing left then is to keep looking and attemting
to explain what we find.