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Re: Dilophosaurus Forelimb Bone Maladies



On Mon, Feb 29th, 2016 at 5:44 PM, Tim Williams <tijawi@gmail.com> wrote:

> I know it sounds counterintuitive, but theropods like _Dilophosaurus_
> might not have used their forelimbs much in predation.  In general,
> the forelimb had limited reach, highly proscribed mobility, and was
> incapable of one-handed (unimanual) prehension.  I'm not arguing that
> the forelimbs were doing nothing at all.  Small prey could be seized
> with the jaws, and dispatched with the hand claws - although this
> would be a bit difficult when the hands were so far from the mouth.

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.

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.


> 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. Check out Roger's enviable physique at the link below:

https://urldefense.proofpoint.com/v2/url?u=http-3A__www.dailymail.co.uk_news_article-2D3110240_Forget-2DDave-2Dmeet-2DRoger-2Dgiant-2Dgrey-2Dkangaroo-2D&d=CwIDAw&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=x82f3Wlkwtmbr1z8IAt9jA&m=NMa_uhOEC_4dXKYBFAa80QN7uDFjYf0q2mPwgxg5dPY&s=6Cc-3UXutWAqF7B5qnQboSr37nwpyZFIGhciIX1vsKc&e=
 
pictured-stalking-suburbia-2m-red-rival-emerges-crushes-buckets-fun-BIGGER.html
 
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Dann Pigdon
Spatial Data Analyst               Australian Dinosaurs
Melbourne, Australia               
https://urldefense.proofpoint.com/v2/url?u=http-3A__home.alphalink.com.au_-7Edannj&d=CwIDAw&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=x82f3Wlkwtmbr1z8IAt9jA&m=NMa_uhOEC_4dXKYBFAa80QN7uDFjYf0q2mPwgxg5dPY&s=s2R6GBVEAPSIX7ha_I1ravUBA1wqhGXxypzmYq_9QWg&e=
 
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