Re: Planet Dinosaur Ep 2

[Tim Williams <tijawi@gmail.com>]

Dann Pigdon <dannj@alphalink.com.au> wrote:


> 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.


Yes - at the end of the day, the aim is to kill the prey.  There's
more than one way to skin a protoceratopsian, after all.


> 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.


Agreed.  The _Velociraptor_-_Protoceratops_ association is far more
indicative of dromaeosaurs targeting large herbivores - and by "large"
I mean at least as large as the predator.


> 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.


That's the way I picture it too.


Interestingly, the dromaeosaur _Balaur_ is reconstructed with *two*
enlarged, hyperextensive pedal unguals per foot.  Was this an
adaptation for extra grip?  Such as when straddling the back of an
iguanodontian or titanosaur?  Aside from the functionally tetradactyl
pes, _Balaur_ shows additional modifications of the pelvis and
hindlimb that have been tied to increasing hindlimb strength (and
reinforcement?).  The forelimb includes a fused carpometacarpus and
functionally didactyl manus with limited mobility - these characters
may have helped reinforce the forelimb during two-handed grasping of
large 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.


I know _Velociraptor_ had quill knobs along the ulna, but there's no
direct evidence that it had long forelimb feathers.  Personally, I
very much doubt that it did. If any remiges were present, they might
have been short and stunted, perhaps even bristle-like or spine-like.
In other words, more like the structures on the tail of
_Psittacosaurus_  (although shorter) than the elaborate plumage of
microraptorines and birds.  That would explain the quill knobs, and
allow the forelimbs of _Velociraptor_ to actively engage in prey
capture without soiling or damaging the forelimb plumage.







Cheers

Tim