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(fwd) Mammals as a cause of Dinosaur extinction



On 16 Dec 1997 05:49:02 -0500, "Stan Engel"
<thorisporn@worldnet.att.net> wrote:

((I posted this previously in another news group))

Why does Stephen Jay Gould completely ignore the possibility that
mammals
may have been a factor in the extinction of the dinosaurs some 65 mya.
Instead, he says that mammals and dinosaurs co-existed throughout the
Jurassic and Cretaceous and that this demonstrates that mammals did
not
consume the Dinosaur young leading to the demise of that group. I
remember
this theory from a 1950's textbook.

Giant reptiles (turtles) have "ruled" the Galapagos islands for a long
time. It is my understanding that recently imported dogs and cats have
caused a decline in the turtle population due to their predation of
turtle
hatchlings. The same predation has also reduced the population of the
other
Galapagos "rulers", the Iguanas. Why is it not a feasible possibility
that
newly evolved (Late Cretaceous that is) placental mammals damaged the
dinosaur population by eating their young. The adult Dinosaurs (just
like
adult Galapagos turtles) would be invulnerable to mammal attack but
their
young would not be so lucky. Question--- When did definable placental
mammals evolve? Was it not in the Late Cretaceous, at about the same
time
that the number of Dinosaur species declined?

Newly imported mammal species also exterminated the "rulers" of
Mauritius,
the Dodos, some 3 centuries ago and seem to be doing the same today to
the
ruling Tuataras, Kiwis and Parrots of New Zealand. In addition, it is
my
understanding that the largest predator of the Paleocene (post
Dinosaur)
was the 2 metre tall Diatryma which was eventually superseded by
mammalian
Creodonts and true carnivores. Is my understanding correct? If
Diatryma was
destroyed by placental mammal competition why not Troodonts or
Velociraptors.

I do not claim that mammals were the sole or even a major cause of
Dinosaur
extinction. I believe that it was a factor and should not be summarily
dismissed.