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Re: large theropod body config and predation



Larry Dunn wrote:
>Are the Car'ids believed to have preyed upon sauropods?
        I had rather imagined they ate anything they could get their teeth into.

>How does one explain the difference in teeth between the Car'idae and the 
>Tyr'idae?
        As far as general differences go, I realize this sounds like a
cop-out, but ou have to remember the differening ancestry of the two. One of
them is a coelurosaur, and one a carnosaur (?), and this brings a whole big
bucket of evolutionary baggage along with it. They each found solutions to
their particular macropredatory problems in their own way, exapting their
former structures to new funtions.
        As far as the teeth are concerned, I imagine the common assertion
that tyrannosaur teeth were for stabbing and crushing is probably a good
place to start. As for charcarodontosaurids, I guess they are part of the
general allosauroid predation mode, whatever that is: attack with arms,
Holtz; attack using teeth to stab like a sabertooth, Bakker; Slice with
teeth, Paul; etc. etc. I suppose their teeth could have been used (as
suggested here and elsewhere) to punch out wounds like a shark. I for one am
open to suggestions.

>Was it driven by selection or simply a development of what 
>earlier forms offered?
        I would almost guaruntee you that selection was involved, as teeth
are a major part of a Mesozoic theropod's interface with the rest of its
ecosystem.

>I am trying to understand the difference in 
>the "lifestyles" (if I can be so bold) between the Tyrannosauridae 
>and the Carcharodontosauridae -- does the answer lie in the 
>teeth?
        It is possible that the evidence lies in the teeth, but the answer
itself more likely lies in a combination of phylogeny, ecology, and perhaps
paleobiogeography.
        ON way to go about this persuit is to first demonstrate that there
was a difference in lifestyles, preferrably by describing the lifestyles
themselves (as you have attempted). Then you should consider why such a
difference may have come out in terms of phylogeny, ecology, and
paleobiogeography. Then you can look at the anatomy.
        OTOH, the commonly preferred method is to do this in the opposite
order. Look at the teeth and say "these are different from those", then look
at the the phylogeny, ecology, and biogeography (and anything else I
forgot), and then suggest lifestyles for the two.
        Either way you go about it, I think you personally are skipping the
middle step. :)

>Thus Kent, oh princes, bids you all adieu
>He'll shape his old course in a country new
        What manner of beast is your crocodile?
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      Jonathan R. Wagner, Dept. of Geosciences, TTU, Lubbock TX 79409
      "The cost of living hasn't affected its popularity." - Unknown