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Re: Terrestriality is a bias



> Tracy Ford wrote:
> 
>             What about burrowing animals? We know _Thrinaxodon_ and
> _Cistecephalus_ were burrowers because they were found in burrows.
> Bakker says Drinker was found in a burrow, but does anyone believe
> him? Not many, because he?s Bakker. There are some things that Bakker
> says that I disagree with, but this I think he may be right. Also
> _Protoceratops_ is now considered by a few to have been a burrower.

Perhaps we should change the term "Cretaceous sheep" into "Cretaceous
warthog"?

As far as burrowing goes, I'm sure there were at least a few species of
dinosaur that managed it. There are burrowing members of many modern
groups of animals (mammals, reptiles and birds) that aren't all that
different from their close relatives.

Personally I don't think there were any ARBOREAL theropod species.
SCANSORIAL perhaps, but all non-flying theropods seem to have had legs
that were well adapting to walking or running around. Even the flyers
never included the hind limbs into the aerofoil surface, unlike
pterosaurs and bats (and most mammalian gliders). I think there was a
good reason for this: even the best tree climbing theropods still spent
a considerable amount of time on the ground, as do/did their flying
descendants. Hence SCANSORIAL rather than ARBOREAL. I suspect fully
arboreal creatures that evolve flying or gliding surfaces end up
incorporating the hind limbs into them, since many of the most arboreal
creatures seem to be sprawlers rather than upright walkers (with perhaps
primates being the exception - and hence the only mammals ever to evolve
into fully bipedal forms?).

-- 
____________________________________________

        Dann Pigdon
        GIS Archaeologist
        Melbourne, Australia

        Australian Dinosaurs:
        http://home.alphalink.com.au/~dannj
        http://www.geocities.com/dannj.geo
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