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Re: dino-lizers



On 4/19/2011 10:51 AM, Jason Brougham wrote:
If a theropod is a scavenger, what will its gut contents look like? Will they 
be more likely to contain bone, since the predator that kills the animal might 
preferentially take the viscera? And a gut full of soft tissues, of course, 
probably won't preserve. From what I know of small theropod gut contents we 
usually see small animals that were probably swallowed whole, or else whole 
limbs of small animals. I'll look if I can find any supporting references on 
what scavengers' gut contents look like. Is it mostly small fragments, or whole 
limbs, or whole bones, or what.

Trying to parse this --

1) Lammergeiers (G. barbutus) and crocs eat a lot of bone, and make a nice phylo-bracket -- the bird specializes in marrow-bones, while I presume the croc's bone intake could be characterized as incidental but significant. I speculate that unless one of these bone-eaters was preserved almost immediately after eating, there would be very little bone to be found in the gut, the stomach acids being so strong.

2) Small theropods are apparently found w/ bone preserved in the gut rather frequently.

3) Large theropods are apparently -- (again, I weasel w/ "apparently" -- my knowledge of the material is not what I would like it to be -- corrections and additions greatly appreciated) -- NOT found w/ large bones preserved in the gut, but some smaller bones are known (e.g., fishbones in Baryonyx).

4) Although I would imagine (scaling up from G. barbutus) that the swallowing capacity of the larger theropods might be very impressive, I would assume the marrow bones of the larger herbivorous dinosaurs could not be utilized by any vertebrate scavenger due to their size. I would also assume: a) such items as vertebrae or even small-brained sauropod heads are lacking in nutritional value b) the percentage of carcass that is muscle declines as carcasses get bigger, and the percentage that is either bone or viscera has positive allometry. It follows that any obligate scavenger relying on large herbivorous dinosaurs would need a steady supply of fortuitous corpses.

A relevant question is: have small bones been found in the gut regions of Cretaceouc crocodilians? If the answer "no", then I would think the presence of small bones in various theropod guts are a indication (albeit counter-intuitive) of a primarily predatory lifestyle/digestive system.

Still, the thought of a "terrestrial Lammergeier" is intriguing -- adopting "T.rex was a ground-bound Lammergeier" as a temporary working assumption, what would the most logical marrow-bone "donor" be?