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Re: polar sauropods
On Sun, 6 Dec 1998, Gautam Majumdar wrote:
> John Bois <firstname.lastname@example.org> wrote
> >Dwarfism is not the only response to insular environments. Several
> >species tend to grow bigger, eg., birds, rodents, shrews. I suppose one
> >should ask: are dinos more analagous to birds or elephants (which do
> >become reduced in size) in this
> I thought that availability of food would be the primary determinant between
> gigantism and dwarfism in island environments free from predators. NZ and
> Madagascar are islands but pretty big with lots of resources giving rise to
> gigantism in birds. Dwarfism in elephants occurred only on small islands with
> limited resources. Sri Lankan elephants are not dwarf.
Presumably dinosaurs on NZ would have predators--their dinosaur brethren.
This might have provided an active selective force for large size.
Also, species which are selected for small size by mainland predators may
experience a "release" from this pressure and grow bigger on
Elephants, on the other hand, for all we know, may be selected for big
size for predator immunity. Landing on some predator-less island they may
then approach a new, small, optimal size.
Then again, forage might be all important.
This is still a very wide-open question.