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Re: dino-lizers



On 4/19/2011 12:59 PM, David Marjanovic wrote:

Four times is not "rather frequently", is it? Can we do meaningful
statistics with such small sample sizes?

Who is doing statistics? If small bones are preserved in a given animal, then does one need a large sample to rule out crocodilian strength acids in that animal? I will grant that the logical conclusions that can be drawn from the lack of strong acids are debatable, though.

Importantly, preserved gut contents other than bone are just about never
preserved. Likewise, coprolites don't seem to contain anything
identifiable other than bone, pollen/spores and/or phytoliths.

Are bones preserved in the scat of scavengers? In my personal observation, the answer is "no", but the question is still very much open in my mind.

 3) Large theropods are apparently [...] NOT found w/ large bones
 preserved in the gut, but some smaller bones are known (e.g.,
 fishbones in Baryonyx).

Correct. IIRC, there's also an iguanodontian vertebra in *Baryonyx*.

Again, were Baryonyx a scavenger, I would expect (speculatively, at least) those bones to be long gone, i.e., not preserved.

 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.

Why? Crocodiles have legendary stomach acids.

Exactly. As do Lammergeier. The argument is not that crocs are scavengers -- the argument is that a critter that eats a lot of bone evolves very strong acids -- hence, the presence of bone preserved in the gut indicates that bone was not very important as a dietary component, which seems unlikely in a scavenger.

The argument against terrestrial obligatory scavengers remains the one
from that lifestyle being a net loss of energy.

I do not disagree that the lifestyle seems highly impoverished. But to pursue the G. barbatus analogy, has the notion that a large theropod might be able to easily swallow and digest (as example) an entire 1 meter femur been considered in that calculation?