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Re: JFC-Bloodiest Battle ??

Mike;

I agree. I admit it is arm waving. My point is that the default should not be active predation -- other options are viable, even if it is difficult to distinguish between them morphologically. Varanoids have low wide skulls, crudely like that of crocodilians (for the sake of this argument). Allosaurus and a number of other large headed theropods have extremely narrow preorbital regions, quite in contrast to varanoids. Take a look at the dorsal view of the skull of Monolophosaurus or Sinraptor. While vertical loads might be accommodated, I am less certain about resistance to torque along the long axis of the preorbital region, especially given all the pneumatic penetration of the region.

Given the lack of similarity between theropods and living terrestrial vertebrates, it would not surprise me that they are making livings in ways unlike anything around now, including a life based primarily on scavenging. As Peter Dodson once wrote "let dinosaurs be dinosaurs."

Dan

Mike Habib wrote:
Allosaurus, like Sinraptor and Monolophosaurus, has an exceedingly narrow preorbital region. All three are like a pair of scissors and quite unlike Tyrannosaurus with arched and fused nasals. I doubt Allosaurus was capable of sustaining great stresses, especially given the extensive pneumatic system enclosed in the narrow skull. Given the abundance of Morrison sauropods, Allosaurus might have been primarily a scavenger, rather than a predator, although that is pretty much am waving. Jurassic Scavenger Club anyone?

An open skull construction need not mean that the maximum loads are low - depending on the particular strain distribution, a kinetic skull can often take fairly substantial loads without failure. A more heavily built skull may indeed be stronger still, but I would be hesitant to assume that a more open, mobile skull morphology entails carrion feeding. Varanids, for example, have a very open skull construction, with a high degree of cranial kinesis, and yet are active predators of a range of prey items.

Cheers,

--Mike H.


Michael Habib, M.S.
PhD. Candidate
Center for Functional Anatomy and Evolution
Johns Hopkins School of Medicine
1830 E. Monument Street
Baltimore, MD 21205
(443) 280-0181
habib@jhmi.edu



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