Re: [BARYONYX]

[pwillis@ozemail.com.au (Paul Willis)]

I see this word and I just can't help myself!

>> b: CROCODILES
>> Here you have elongate jaws, mostly carinate and occasionally serrated
>> conical teeth, but crocodile teeth variate along the jaws, and can be
>> large toward the back of the jaws, almost as large as the anterior
>> teeth---this is especially evident in the gharial, whose teeth are
>> nearly all the same size. Of fisher crocs, the forelimbs are used either
>> to walk with, or swim. Now, Baryonyx, hypothetically, could swim, and
>> definately could have walked, but the forelimbs were, most likely, not
>> used. As above, they were quite small.

>Now we've run into a slight snag. Again when Baronyx was first found the first
>thing that popped into everyones head when they saw the jaw was that it looked
>very suchian. So of course everyone automatically (for some strange reason)
>assumed that it as a fish eater (of course the *lepidotes* remains in the
>stomach wer also a clue) Point is that most crocs are not fish eaters. Sure
>they live in a habitat frequented by fish, but for most fish makes up a small
>part of the diet. The obvious exception to this is of course the gharials and
>the false gharials. They are specifically designed to eat fish and only fish
>(and as far as I know, that's all they do eat.) Other crocs like niles' and
>indopacific crocodiles have a diet consisting of any animal that comes to
>drink. They prefer terrestrial animals. So why does everyone assume that since
>Baronyx was crocodile like, that it was a pure fish eater. If it was anything
>like modern crocs then it would most assuredly prefer land animals.

I concur with the second opinion. The crocodile-like features associated
with Baryonyx (festooned mouth margins, differential tooth size and
elongation of the snout) are features seen in crocs that are not fish
specialists but generalists. Comparisons with gavials and Baryonyx are
extremely misleading. Infact Baryonyx looks most like Baru, one of our
extinct crocodiles from Riversleigh, Bullock Creek and Alcoota.

This snout morphology is more a consequence of housing teeth that vary
greatly in size (increased pseudoheterodonty equates to increased
festooning), so the crocodile-like features of Baryonyx are more likely to
be an adaptional complex associated with housing large pseudocaninies. Now
the question becomes what Baryonyx was doing with pseudocanines? Could we
be looking at a proto-saber-toothed dinosaur? (Whimper... I think I''ve
just started a therad I don't want to get into).

>> Crocodiles, unlike bears, are developed almost to the exclusion of all
>> other forms of habitat, to the water, while bears are very varied in
>> their place of residence (though all species are excellent swimmers).
>Modern crocs are, but lets not forget that the crocodylatarsia were quite
>divers in their day. Even today crocs are known to make long voyages to other
>water holes. I say that modern crocs are more developed to tackling prey from
>the water, than to just a simple watery existence.

Once again, I concur with the second author. When looking over the history
of crocodiles, their current exclusive restriction to water is misleading.
In the past crocs have had a ball of a time on the land, on more than one
occassion, and don't forget that one of my little buggers may even have
been climbing trees. Even among living crocodiles, Paleosuchus may be
spending as much or more time out of water than in.

>It sounds to me like Baronyx was designed to take animals down from a
>riverbank. Perhaps Baronyx was the dinosaur equivelant of a crocodile (even
>though deinosuchus should take that cake) or was in competition with crocs as
>shoreline hunters.

Considering Dienosuchus was on another continent 50 million years later, I
don't think they represented much of a threat to Baryonyx (are you scared
of Kambara*?). The croc competition for Baryonyx would have been
Goniopholis and probably Bernissartia, both of which probably did not
exceed 2 metres in length. Not much of a competition.


>> 3: THE NOSE
>>
>> The snout of *Baryonyx*, though often cited as similar to the crocodile
>> snout, is actually a near miss for such an analog, as based on several
>> features:
>> i)   external naris located back from tip, top, and back of snout

Same as many crocodiles.

>> ii)  orbits located laterally, with some binocular vision

Same as various extinct crocodiles (Quinkana, Pristichampsus, Mekosuchus
yadda, yadda, yadda) and some extant crocs (Paleosuchus and Osteolaemus).

>> iii) teeth reduced in size towards rear of jaw

Same as many crocs (depending on the degree)

>> iv)  anterior teeth forming "piercing" apparatus actually analagous to
>>      a bear-trap*

OK, you've got me there! (Although Baru and Pallimnarchus spring to mind).

>> The snout with the posteriorly-displaced nares could mean that Bary
>> could probe the waters without having to splash around a lot and lunging
>> after leaping dinner, like certain ursines. This snout, like the kiwi or
>> platypus (you heard me, _platypus_!) could function as a probe for muddy
>> water or even the muck itself, meaning the food was like the mudskipper,
>> oir catfish, who bury themselves, or other aquatic life. The only
>> problem with this is that kiwi's and platypi have nares at the tips of
>> the their snouts, platypi being able to seal these off.
>I'm suprised that you didn't site cranes and other wading bierds who quietly
>probe the bottom of river banks and mudwallows for fish.

Perhaps it was psychic and just thought its' prey to death. Can we hold
fire on the speculation front? I have a weak stomach.

I guess what I'm trying to say is that there is more than one reason why
the snout of Baryonyx resembles that of some crocodiles, but before we
start guesing why, let's at least get our analogies correct. The crocodiles
that Baryonyx most resembles are ambush predators of terrestrial prey. I
would be happy to leave it at that.

*An Australian Eocene crocodile


Cheers,

Paul


Dr Paul M.A. Willis
Consulting Vertebrate Palaeontologist
Quinkana Pty Ltd
pwillis@ozemail.com.au

Interesting fact:
Lorne Greene had one of his nipples bitten off by an alligator while he was
host of "Lorne Greene's Wild Kingdom.