[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: mammal mystery



> If you
> ask me, a group of species which keeps no really small things (moussize)
> among their members is doomed.

I think a few of us are forgeting that in the Hell Creek Formation the
really small mammals actually lost more species than the big dinosaurs (note
that the ectotherms took a fairly minor hit):

The Death Count
Dinosaurs: 19 out of 19 species
Mammals: 27 out of 28 species
Crocodiles: 3 out of 5 species
Amphibians: 6 out of 8 species

        Thus, more really small warm-blooded species went extinct than the
really huge ones (this is from the work of Archibald and Bryant, I have the
ref.). And ectotherms, regardless of size, rode it out comparitively nicely
(example: Champsosaurus was Upper Cretaceous (?Campanian) till into the
Eocene, I think)
 
>> Dinosaurs were bipedal.  This hampered them in close cover where things
>> suc as mammals, snakes and lizards had an advantage of close-to-the-ground
>> stealth.

        Stealth was not needed by ceratopsians and hadrosaurs, for instance,
because they roamed and nested (at least the hadrosaurs) in great herds,
thus providing strength by numbers. I have spent a lot of time trudging
through jungles in central America, and believe me even big animals can be
really hard to spot in even sparse jungle. Also- theropods appear to have
been crouching low to the ground to stalk prey as shown by the elongated
"human tracks" that we hear so much about from our creationist friends.

Sam Girouard
sampaula@pacificrim.net