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Re: Planet Dinosaur Ep 2



On Fri, Sep 30th, 2011 at 10:00 AM, Tim Williams <tijawi@gmail.com> wrote:

> Dann Pigdon <dannj@alphalink.com.au> wrote:
> 
> > This may suggest that velociraptorine unguals would have been better suited 
> > to the sort of
> hit-and-
> > run predatory tactics seem in poisonous snakes or great white sharks. A 
> > series of quick
> plunging
> > attacks with the foot claws followed by a rapid retreat to evaluate the 
> > situation. Eventually
> the prey
> > might have succombed to either shock or blood loss from the repreated 
> > strikes, with a 
minimum of
> > risk to the dromaeosaur in question. This is pretty much the tactic 
> > employed by secretary birds
> > against snakes.
> 
> All this suggests that the second pedal claw of dromaeosaurs was used
> to slash through flesh - which is what Manning et al. (2005) endeavor
> to refute.  But the hit-and-run tactics might have worked against
> smaller prey, for which a deep penetrating wound would be potential
> fatal.

I was envisaging more of a penetrating wound, rather than a slashing one, when 
it comes to getting 
through the flesh. I would expect a slashing claw to be more recurved and much 
thicker (more like 
the claws of felids). Velociraptorine 2nd unguals are much less curved than a 
cat's claw, and much 
narrower. It would seem that the shallow curve of a dromaeosaur foot claw would 
have 
compensated quite nicely for the arc of movement of the toe and foot during a 
forward kick, 
resulting in the tip penetrating straight into prey rather than raking across 
it.

Given the likely thickness of the dorsal hide (with or without scutes) you 
would expect for most 
reasonably large dinosaurs, such jabbing attacks might have been better aimed 
at the neck or belly 
(or cloaca - ouch!) of larger prey. That's assuming that the smaller-bodied 
velociraptorines 
targeted such large prey very often (or at all). A few Deinonychus teeth 
associated with a 
tenontosaur isn't exactly a smoking gun for active predation of large prey.

As for gripping onto large prey - the forelimbs would seem to be better 
designed for this, as they 
had three highly recurved claws each, and with the hands facing inwards they 
may have better 
resisted side-to-side thrashing of the prey item. The feet however not only had 
just one grippable 
claw each, but it was also far less curved than those of the manus, and its 
narrower profile would 
seem to make it less capable of withstanding such sheering or twisting forces. 
Plus there is the 
ankle joint with its restricted plane of movement. Side-to-side thrashing of a 
large prey item may 
have played merry hell with the ankle joint, if the predator had both its 2nd 
toe claws embedded to 
the base within the prey.

However I find it difficult to believe that a creature with a seemingly fragile 
fan of feathers on each 
forelimb would go around bear-hugging large thrashing prey items at all. That 
sounds like a likely 
recipe for a bad plumage day.

-- 
_____________________________________________________________

Dann Pigdon
Spatial Data Analyst               Australian Dinosaurs
Melbourne, Australia               http://home.alphalink.com.au/~dannj
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