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Re: No dinosaurs in Quebec, Canada?



On Mon, 18 Nov 1996, Gautam Majumdar wrote:

> In article <199611141919.OAA11241@juliet.ucs.indiana.edu>, Stan
> Friesen <swf@ElSegundoCA.NCR.COM> wrote
>
> >No known dinosaurs lived in the sea. All were land animals.
> >
> Is there any generally agreed explanation why over their 160 MY reign
> dinosaurs did not venture to exploit the aquatic niches ?

        That's a baffling one. Perhaps the competition from sea-crocs,
mosasaurs, ichthyosaurs and plesiosaurs was just too much (mammals didn't
go to sea until after all these had disappeared, it seems).
Perhaps only one group (theropods or a subset thereof) had the insulation
necessary for it. It doesn't seem like too many mammal groups have gone to
sea recently, at any rate (whales and pinnipeds were around in the Eocene,
am I right in thinking that desmostylians and manatees were as well?)
        Perhaps they did and we just don't know about it because of holes
in the fossil record, perhaps they did and we don't know about it because
we can't tell from the skeleton alone (an otter skeleton is not vastly
different from a weasel skeleton, a polar bear skeleton is not
substantially different from a brown bear skleton in regards to aquatic
adaptation) so perhaps there were small, web-footed dinos with
dense,oil-coated feathers chasing after fish, crustaceans and molluscs.
Perhaps we will find a theropod with web impressions between the feet
someday.
        Currie and Bakker were supposed to have suggested in a paper that
spinosaurus was in fact aquatic, which might explain the flexibility of
the spine, and perhaps the spines themselves, and while it's perhaps not
impossible that it did spend a lot of time in water (like a polarbear or
otter) there isn't any incredibly good evidence that it did so (although
again, it could be very hard to tell). I am of the opinion that new
fossils will, sooner or later, give us more answers and that eventually
we could find the theropod equivalent of an otter, and if we're clever,
we'll recognize it for what it is.

        Nick L.