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Re: Dilophosaurus Forelimb Bone Maladies

There is rather good direct evidence of _Allosaurus_ predation on _Stegosaurus_, namely two documented cases of _Allosaurus_ pathology caused by stegosaur thagomizers. The first one is the rather well-known (by means of being featured in a certain BBC documentary) punctured _Allosaurus_ caudal described by Carpenter et al. 2005.

The second is this pathological allosaur pubis described in a conference abstract by Bakker:

Also a bite mark on a cervical plate is more consistent with predation than with feeding (Carpenter et al. 2005); this is a part with very low nutritional value, but placed in a way that would make it come in the way of any attempt to bite the stegosaur’s neck.

Besides that, with the challenges of an effective kleptoparasitic lifestyle in large carnivores, and the behaviour of extant predators, I think defaulting to writing off cases of theropod bite marks on large prey as mere scavenging traces is very risky.

All the modern predators that are most similar to large non-avialan theropods in terms of their functional anatomy and inferred ecology (komodo dragons, birds of prey, sharks, large mammalian apex predators) at least occasionally hunt and kill prey their own size or larger.

I don’t see what would stand in the way of a large theropod doing the same. Of course macropredation becomes more challenging with size, but in part that’s because large prey is simply rare. Of course a majority of known dinosaur specimens aren’t fully grown and could be classified as "juveniles" if one likes that term, but there was still a considerable biomass of large prey.

In terms of mere evidence of (at least) feeding, in think the best examples are the surprisingly common theropod bitemarks on sauropod bones from the Morrison Formation (Chure et al. 1998, Hunt et al. 1994, Jensen 1988, Matthew 1908). The prevalent stance is to consider them traces of scavenging, although this hasn’t been universal (Jensen 1988).

Carpenter, Kenneth; Sanders, Frank; McWhinney, Lorrie A.; Wood, Lowell (2005): Evidence for predator-prey relationships: Examples for Allosaurus and Stegosaurus. In: Carpenter, Kenneth: The Carnivorous Dinosaurs. Bloomington, pp. 325-350. Chure, Daniel J.; Fiorillo, Anthony R.; Jacobsen, Aase (1998): Prey Bone Utilization by predatory Dinosaurs in the Late Jurassic of North America, with Comments on Prey Bone Use by Dinosaurs throughout the Mesozoic. Gaia, Vol. 15 pp. 227-232. Hunt, Adrian P.; Meyer, Christian A.; Lockley, Martin G.; Lucas, Spencer G. (1994): Archaeology, Toothmarks and Sauropod Dinosaur Taphonomy. Gaia, Vol. 10 pp. 225-231. Jensen, James A. (1988): A fourth new Sauropod Dinosaur from the Upper Jurassic of the Colorado Plateau and Sauropod Bipedalism. The Great Basin Naturalist, Vol. 48 (2) pp. 121-145. Matthew, W. D. (1908): Allosaurus, a carnivorous Dinosaur, and its Prey. The American Museum Journal, Vol. 8 (1) pp. 3-5.

On 03.03.2016 08:00, Tim Williams wrote:
We have evidence of_T. rex_  predation against large prey, from the
Hell Creek Fm of SD, with a tooth embedded in the tailbone of a large
hadrosaur (_Edmontosaurus_?), which subsequently healed (DePalma et
al., 2013).  Even though the hadrosaur got away, it is evidence of
tyrannosaurs hunting large prey.  Hone & Rauhut (2009) list examples
of evidence of large theropods consuming large prey: e.g.,
_Allosaurus_  vs_Stegosaurus_  (cervical plate bitten through),
_Tyrannosaurus_  v Triceratops_ (pelvis with tooth punctures).
Admittedly, in these cases there is no direct evidence of hunting,
only consumption.

Yours sincerely,

Darius Nau