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Re: Velociraptor scavenged azhdarchid pterosaur



On Mar 4, 2012, at 2:36 PM, "Denver Fowler" <df9465@yahoo.co.uk> wrote:

> Generally speaking, the predator seems more at risk if prey capture is 
> successful than if it is not. Most prey do not seem to want to stand and 
> fight, preferring to run (or fly) away. If the prey is somehow unable to 
> escape then it may fight, and this is when effective immobilisation is 
> crucial. Falcons can stun prey somewhat, if they stoop it from the sky. In 
> hawks, flight does not afford any real advantage to the immobilisation 
> process, other than the element of surprise. Well, other than stability 
> flapping maybe. I don't think the predator needs to wo
> own escape rather than standing there looking a bit embarrassed after a 
> failed attack.

If escape were unimportant then we would expect to see more predators attacking 
large prey.  If attacking large prey is risky then I argue that the ability to 
disengage is at least worth considering.  I don't think we can dismiss it on an 
intuitive basis.  I would also argue that flight gives birds of prey a 
substantial advantage with regards to posture and positioning, the importance 
of which you noted in your post and substantiated in your PLoS ONE paper.  
Flight provides posture advantages through improved mobility, surprise, 
stability flapping, and elevated approach paths.  I assert that flight is 
critical to the prey riding behavior that many raptorial birds utilize.

That said, *near* flight might be sufficient for some of those attributes, too 
- and dromaeosaurids probably had that going for them.  So, I suppose my 
ultimate thought/hypothesis is this: if dromaeosaurids actually engaged large 
prey, then their possession of incipient (or functional - see microraptorines) 
flight anatomy might be inferred to be critical to large prey acquisition.  
Large in this case presumes subequal in mass, not multiple body weights in 
excess.

Cheers,

--Mike

> 
> Relative prey-predator posture is important. It's pretty cool how hawks have 
> learned to place a foot on a prey item's head, to stop that method of 
> retaliation; usually when dealing with "large" mammals. With large bird prey 
> (where pinning by bodyweight is a more 50:50 affair), the predators always 
> seem to get into the position where they are standing atop the victim (almost 
> a mating position), with the feet placed between the victims wings. this 
> limits the ability of the prey to attack, but I think it also minimizes the 
> prey's wings from getting in the way  as the predator is positioned between 
> the maximum extent of the upstroke (may also explain mantling; see our 2009 
> paper). This position is also the safest place to avoid attacks from the 
> prey's head while giving access to the prey's own neck and back. Contrast 
> this with the hyper-dangerous strategy of throat attacks by big cats (where 
> the predator is very close to being trampled), or potentially
> attacking organs through the belly: this would kill a prey item more quickly 
> but subject the predator to the full capability of the forelimbs, hindlimbs, 
> and head. Safer instead to bite down through the back, even if it is mostly 
> bone.
> 
> 
>> In any case, your point is well taken, but the RPR behavior is applicable 
>> (as you noted above) to any prey that cannot be easily contained within the 
>> foot.  So even in a case were the prey was, for example, 20-25% of the mass 
>> of the predator it would count as "large", and your model would be 
>> potentially applicable.  I am not necessarily arguing that dromaeosaurids 
>> did not eat larger prey than average, only that a specimen of a Velociraptor 
>> preserved in the midst of having the snot beaten out of it by a 
>> Protoceratops that probably greatly outweighed it in life should not be 
>> taken to mean that dromaeosaurids routinely attacked prey substantially 
>> larger than themselves.  Suggesting that a RPR strategy might have allowed 
>> predation on animals 50% of the predator's mass does not stretch incredulity 
>> in the same manner as the assertion that mid-sized theropods went around 
>> beating down sauropods or that dromaeosaurids went berserker-style after 
>> prey 400% of
> their own mass or more.
> 
> I agree completely, but it is worth bearing in mind that the "prey riding" 
> observed in various hawks is a viable (and real) behaviour by which a 
> dromaeosaur could subdue substantially larger prey.
> 
> ----------------------------------
> Denver Fowler
> df9465@yahoo.co.uk
> http://www.denverfowler.com
> -----------------------------------
>