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Re: Dilophosaurus Forelimb Bone Maladies



> On Feb 29, 2016, at 1:56 PM, Dann Pigdon <dannj@alphalink.com.au> wrote:
> 
> Why assume that the mouth was involved in predation at all? If I was a 
> dilophosaur, I'd probably 
> make a concerted effort to keep my fragile head crests well away from the 
> action. That kinked snout 
> tip doesn't strike me as having been a heavy-duty tool either. It looks more 
> like the sort of precision 
> instrument better suited to selectively nip at bite-sized chunks (or perhaps 
> soft viscera) than for the 
> rough and tumble of dispatching sizable prey.

Good observations - to me, the simply explanation is that it didn't dispatch 
sizable prey. Most living predators eat things that are effectively bit sized 
(maybe a couple of bites). That goes for everything from canids to varanids. 
Yes, a few clades have their one or two big game specialists, but those are 
rare. Only cats really have a bunch of big game hunters, but big felids are 
just weird.

Dilophosaurus may have just been a typical sort of terrestrial predator: eating 
bite sized stuff (which, given the size of Dilophosaurus, could include a lot 
of animals).


> 
> Perhaps dilophosaurs were more like giant secretary birds, using their feet 
> to immobilise prey much 
> smaller than themselves, then employing their forelimbs to dispatch (and 
> perhaps partially 
> dismember) them. The head might have only come into play once the prey was 
> safely dead.

I love the image! The issue, in my mind, is that the hands can't get anywhere 
useful unless the Dilo squats, and it can't see its hands or feet very well at 
all, either way. Secretary birds, by contrast, can watch where they're 
stomping. But maybe if the prey is slow that doesn't matter as much.


> 
> 
>> The clawed forelimbs might have been used for agonistic behavior,
>> similar to extant macropodines (who also use them for slow/pentapodal
>> locomotion).   Senter & Juengst actually mention intraspecific combat
>> as a possible cause of _Dilophosaurus_'s injuries.
> 
> I was thinking the same thing. Adult male red kangaroos have enormous 
> forelimb, shoulder and 
> pectoral muscles for intraspecific combat. Females of the species get by with 
> much less robust 
> forelimbs, demonstrating that the robust forelimbs of the males aren't 
> necessary for pentapodal 
> locomotion alone. 

Good point.

Cheers,

--MBH