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Re: Velociraptor scavenged azhdarchid pterosaur

On Mar 4, 2012, at 2:39 AM, Dan Chure wrote:

> Things do not always go smoothly for predators, especially when feeding 
> on prey their size and larger. Injuries may not be uncommon.

Which is precisely why large terrestrial predators rarely attack prey near 
their own size, pack hunting obviously excepted.  This is the point, of course, 
where reams of angry list members chime in with their favorite "here's an 
example of predator X killing unusually large prey item Y" - but these are 
overwhelmingly strange, desperate cases - that's why they got filmed, noted, 
etc. in the first place. On the whole, predators kill things smaller than 
themselves (smaller, in the case, being relative to the total biomass of 
predator(s)), and they typically kill juveniles.  A severe injury that prevents 
further foraging is ultimately lethal.  If lethal wounds were common, then we 
wouldn't have many predators left.

> Seriously, I am interested in whatever evidence you might have in 
> interpreting  the Protoceratops-Velociraptor specimen as something other 
> than an attempted predation event (maybe going badly for the predator) 
> preserved in progress. If there are alternative explanations for that 
> specimen other than predation and the evidence is such that we cannot 
> choose between the alternatives, then the topic of predation in 
> dinosaurs should probably just be abandoned as a research effort. If we 
> cannot figure out what the hell is going on in such a spectacular 
> specimen as that of the V-P, then why spend any time with tooth marks, 
> bone fragments within rib cages, or any other such material.

It's the same evidence as everyone else has - two animals apparently locked in 
a death match and buried.  What we have is a Velociraptor specimen tangling 
(poorly) with an animal that we would expect to be way out of its league as a 
prey animal.  And, in fulfillment of those expectations, the Velociraptor died 
in the battle.  Granted, so did the Protoceratops, but mutually assured 
destruction is not exactly a sound foraging policy.  Could it be a desperate 
predation attempt by an unexperienced Velociraptor?  Absolutely.  However, it 
could just as easily be the result of a failed nest-raiding attempt, for 
example.  After all, the same general region that gives us the fighting 
dinosaurs also has yielded Protoceratops nests, and a large herbivore taking 
substantial risk to engage a nest predator is much more consistent with 
neontological patterns of behavioral ecology than an experienced predator being 
suicidal (again, that doesn't preclude an *inexperienced* predator doing 
something suicidal).  That's not to say that I am convinced the fighting 
dinosaurs are not the result of a failed predation attempt, merely that it is 
not the only possible explanation.  If memory serves, this issue regarding the 
V-P specimen has been discussed at length on the DML previously; I presume the 
archives still have a record.


--Mike Habib

> On 3/3/2012 11:32 PM, Habib, Michael wrote:
>> True, but that assumes that the "fighting dinosaurs" preserves a one-on-one 
>> predation attempt, which I personally doubt (actually, it may not be a 
>> predation attempt at all - consider that the Velociraptor appears to have 
>> been in the process of being mangled badly).  Incidentally, the 9kg mass for 
>> the azhdarchid in the new paper is probably too low by a fair margin (9kg is 
>> about the mass of a large albatross).  In any case, we cannot absolutely 
>> rule out predation, but it would still seem that scavenging would be the 
>> preferred hypothesis in this case.
>> This discussion/debate brings up an interesting question: what evidence 
>> should we, as paleontologists, require before tentatively accepting a 
>> scavenging hypothesis for a given preserved feeding event?  And conversely, 
>> what evidence should be required to tentatively accept a predation 
>> hypothesis?
>> --Mike Habib
>> On Mar 4, 2012, at 12:54 AM, Tim Williams wrote:
>>> Mickey Mortimer<mickey_mortimer111@msn.com>  wrote:
>>>> Scavenging's certainly possible, but since the closely related Deinonychus 
>>>> is generally accepted as predating Tenontosaurus (which is about as heavy
>>>> compared to Deinonychus as Quetzelcoatlus is compared to Velociraptor), I 
>>>> don't see how we can favor one hypothesis over another.  Sure I'm assuming
>>>> that the Velociraptor was found singly, but if Roach and Brinkman (2007) 
>>>> are correct that Deinonychus did not live in packs but merely aggregated 
>>>> to kill,
>>>> then a lone dromaeosaurid with parts of a large animal in its belly is 
>>>> just what we'd expect.
>>> There's also the famous "fighting dinosaurs": _Velociraptor_ preserved
>>> in combat with _Protoceratops_.  The _Velociraptor_ (an adult) is
>>> estimated to have have weighed around 24 kg, the _Protoceratops_ at
>>> least that much.
>>> For the Hone&c study, the _Velociraptor_ was a sub-adult estimated to
>>> have tipped the scales at 13 kg.  The pterosaur is estimated to have
>>> weighed at least 9 kg.  So IMHO the contest between _Velociraptor_ and
>>> pterosaur would be less daunting than _Velociraptor_ vs
>>> _Protoceratops_.  Also, pterosaurs (even azhdarchids) were less adept
>>> on the ground than velociraptorines.  Would it really have been
>>> prohibitively difficult for a  _Velociraptor_ to attack an azhdarchid
>>> of comparable (or even lesser) body mass?  Even if the pterosaur
>>> weighed substantially more than the _Velociraptor_, predation still
>>> seems to be well within the realm of possibility.
>>> Cheers
>>> Tim
>> Michael Habib
>> Assistant Professor of Biology
>> Chatham University
>> Woodland Road, Pittsburgh PA  15232
>> Buhl Hall, Room 226A
>> mhabib@chatham.edu
>> (443) 280-0181
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Michael Habib
Assistant Professor of Biology
Chatham University
Woodland Road, Pittsburgh PA  15232
Buhl Hall, Room 226A
(443) 280-0181