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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
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?