RE: WILL THE REAL DEINOCHEIRUS PLEASE STAND UP ?!?

[dale mcinnes <wdm1949@hotmail.com>]

Well .. there goes one hypothesis stomped into the ground. I'd be intriqued if 
*D*
turned up with a massive hooked beak though. We certainly need a skull.

To answer one of your questions on what ornithomimosaurs would be doing running 
around
a carcass [avoiding bigger predators/ threat display] they just might have .. 
in sufficient
numbers .. mobbed larger predators. I know .. it's stretching it a bit. 

For locating carcasses .. perhaps they followed big *D* around. *D* should have 
been tall 
enough.

I visualized ornithomimosaurs as using their forelimbs to nimbly process or 
separate flesh 
for the skull and jaws to ingest .. not to bring food to the mouth.

If *D* was big enough and had massively feathered forelimbs .. it may have 
backed off even
large predators at a site particularily if there were more than one big *D* 
approaching a kill.
I doubt that they would have been the 1st one's there but .. maybe .. were big 
enough .. tall
enough .. scary enough to take a kill from other predators.

Just offering an hypothesis .. which if totally killed .. simply gets one more 
out of the way.

Always fascinating.

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> Date: Fri, 8 Nov 2013 16:15:18 +0100
> From: zthemanvirus@hotmail.com
> To: dinosaur@usc.edu
> Subject: RE: WILL THE REAL DEINOCHEIRUS PLEASE STAND UP ?!?
>
>
>
>
> First of all, thank you for opening up a different sort of discussion than 
> ones about nomenclature or linguistics and for thinking outside the box. That 
> being said, I can't say that I find your hypothesis to be that convincing. 
> I'm not too well-informed regarding the specifics of ornithomimosaur anatomy, 
> but I do think I can react to your statements from the perspective of ecology.
>
>>
>> I see them as Nature's answer to ground hugging Mesozoic terrestrial 
>> vultures.
>> These are animals 10 times the size of modern vultures consuming terrestrial
>> prey .. on average .. 10 times the size of today's African meso-fauna.
>>
>> I see these animals .. not as prey .. but as viscious scavenger/ hunters.
>> Their cursorial adaptations were not designed for them to "run away" .. but
>> rather to "stand their ground" as they competed with other medium and large
>> theropods gathered around a kill.
>
> How do you imagine that happening? Do you picture ornithomimosaurs constantly 
> running around carcasses to avoid other theropods or do you mean to say you 
> see them posturing or threatening other theropods from a safe distance, 
> perhaps constantly changing location and distance vis a vis the competitors? 
> If ornithomimosaurs used speed to scavenge, I would first imagine them 
> quickly running to the scene before other theropods could get there, in the 
> fashion of vultures. However, vultures soar high and have the advantage of 
> 'as the crow flies'. They can easily spot carcasses from far away and get to 
> them quickly. Ornithomimosaurus could not and their competitors, as you see 
> them, would tower over most of them and thus have the advantage of a slightly 
> better long distance view. That's even disregarding that at least 
> tyrannosaurids had excellent smell, large theropods might already be on the 
> scene due to making the kill themselves and navigating through (and seeing 
> over) possibly difficult terrain. Don't imagine (all) ornithomimosaurs living 
> in very open environments!
>
>> Their long necks designed for getting deep inside a carcass. Their long 
>> clawed
>> unguals for scraping flesh from bone. Their long narrow skulls for getting 
>> between
>> ribs and possibly other predators.
>
> Perhaps, but the way you describe this their eating does not seem to be all 
> that quick nor very conductive to your 'standing their ground'. Instead, this 
> makes your scavengers sound like very thorough foragers that would take quite 
> some time to eat from a carcass...and with their heads submerged in body 
> cavities no less.
>
>>
>> But there is a problem that ornithomimosaurs faced that modern vultures 
>> don't today.
>> Most Mesozoic carcasses did not just have thick hides .. they were strongly 
>> armoured
>> [creatopsians/ hadrosaurs/ ankylosaurs/ titanosaur sauropods/ perhaps many 
>> small
>> ornithischians].
>
> This makes sense of massive jaws and teeth in large theropods, not so much 
> for slender necks and heads in ornithomimosaurs. In your scenario, this would 
> leave ornithomimosaurs waiting for a strong predator to open up a carcass 
> after first rushing in to get there first! Also keep in mind that using the 
> front limbs in bringing food to the mouth is not something archosaurs seem to 
> do very much. This may well be irrelevant, however, as ornithomimosaurs are 
> likely to have used their forelimbs for *something*.
>>
>> On the African veldte .. one particular vulture is specially adapted for 
>> ripping open
>> the tough hides of Africa's large herbivorous species. That vulture is the 
>> "King Vulture".
>> Now here's a vulture that is crucial to the clean-up commencement of large 
>> rotting
>> carcasses on the African plains. Many other vulture species are absolutely 
>> reliant on the
>> specialties of this giant vulture to open large carcasses.
>
> You´re clearly referring to the Lappet Faced Vulture (*Torgos tracheliotos*) 
> here. No biggie in itself, but slipping up with such details does not make 
> your case more convincing, unfair though that might seem or be. Also keep in 
> mind that *Torgos* is among the most predatory of vultures and a formidable 
> hunter in its own right. Its robustness may thus have multiple explanations 
> and dominating other vultures could even be little more than a side-effect of 
> those, though I'd consider that to be unlikely. As for other vultures being 
> 'absolutely reliant' on it, perhaps, but this may be a just-so story as 
> smaller vultures seem to have little problem entering a carcass via mouth, 
> anus, genitals or other soft areas. That *Torgos*' massiveness and strength 
> allows it to dominate other scavengers and allows it to handle rougher 
> material when the opportunity rises isn't in doubt, of course.
>
>> Back to the Mesozoic.
>>
>> Enter Deinocheirus mirificus .. the "king ornithomimosaur" specially adapted 
>> for ripping into
>> armoured carcasses. But wait. A beaked skull could be seriously damaged on 
>> such prey. So Nature
>> equiped these deinocheirids with 6 "beaks" .. those nasty clawed unguals. 
>> They don't have to be
>> strongly raptorial at all .. just "solid". Break one .. 5 to more to rely 
>> upon.The forelimbs don't
>> have to be very powerful either .. just strong enough to rip open rotting 
>> multi-ton carcasses.
>
> 'Ripping open rotting multi-ton carcasses' does seem like something you need 
> powerful forelimbs for, if you're going to use them for that task! More so 
> when it comes to, as you mentioned, thick-skinned and even armoured 
> carcasses. The typical archosaurian mode of opening carcasses appears to be 
> by using a big, strong beak or toothed jaws so positing that ornithomimosaurs 
> used their dainty heads for the task seems like an extraordinary 
> hypothesis...and having them use their claws in unison with said head is even 
> more so. That's not saying it's impossible, just that it seems unlikely as it 
> doesn't follow the typical pattern of their greater clade...with very few, if 
> any, known exceptions to that rule. Marabous may have long pointy beaks but 
> note that this may be constrained by their phylogeny, said beaks are 
> proportionally very massive and strong compared to those of other ciconiids, 
> marabous have an allometrical advantage due to being large members of their 
> clade itself and marabous do perhaps habitually scavenge, but not 
> obligatorely nor exclusively.
>
> As for * Deinocheirus*, it seems rather a risky proposition to me to claim 
> that its ecology must have mirrored that of other ornithomimosaurs, just on a 
> more massive scale only because its size did so. Ornithomimosaurian though it 
> is, *Deinocheirus* is a very basal one and what we have of it suggests it to 
> be an outlier in most or every way. This does not make it likely that it 
> resembled other ornithomimosaurs much in lifestyle. In your scenario, we'd 
> still expect some of the characteristics of its kin in *Deinocheirus* itself. 
> If I understand you correctly, you would expect *Deinocheirus* to be yet 
> another fast cursor, albeit a far larger and more massive one. It would have 
> to be, if it needed to make its way to carcasses flightlessly given the 
> likely distances involved, the tough competition and the nutritional needs of 
> a scavenger that large. Instead, *D.* appears to have been a graviportal 
> creature. In your scenario, this would only make sense if it could actually 
> claim carcasses on the spot...or hunted large prey itself, which would refute 
> your hypothesis. The latter would also ignore that a huge graviport with 
> likely dainty forequarters seems like an odd candidate for a big game hunter. 
> *D.* reminds me more of a moa than of a phorusrhacid. in coelurosaurs (or 
> just birds) very small heads seem to correlate with herbivory or omnivory 
> rather than with (hyper-)carnivory, best examplified by galliforms and 
> ratites. Of course, we don't know what size the head of *D.* was, but 
> positing it to have had a large head is at odds with everything we know of 
> ornithomimosaurs (though the big guy seems to have cared very little for such 
> rules, of course.)
>
> I did think of *D.*'s body being described as rather narrow, but I wonder how 
> one qualifies that. Are we talking 'somewhat narrower than expected', 
> 'narrower than, say, *Therizinosaurus*, 'narrow in an absolute sense, given 
> its size*? Lacking such precision in terminology, 'narrow *D.*' may still 
> have been a tad too big to comfortably slip into carcasses.
> Regarding *D.*'s arms, these are certainly intriguing structures and I have 
> to confess that I do not have any hypothesis regarding their use that I 
> prefer or find totally convincing at this moment. This includes yours. The 
> problem also lies with *D.* being so unique: It has no predecessors, no 
> antecedents and no equals. It just appears in the fossil record in all its 
> bizarreness. We really don't know if other 'deinocheirids' were comparably 
> huge, graviportal or sail-backed. For all we know, it might have been an 
> extreme outlier even among its closest relatives.
>
> Scavenging in large theropods in general may well have been a rather 
> different affair from that in modern mammalian carnivores or even vultures. A 
> large theropod could have swallowed many a small carcass whole and could 
> likely take huge mouthfulls of flesh and bone out of large ones. Gulls and 
> herons may give you a clue about the swallowing capacity of small theropods 
> and now translate that to, say, *Tarbosaurus*. The presence of such huge 
> predators with a corresponding gape compares rather poorly to the 
> comparatively gentle nips much smaller carnivorans take. Scavenging in the 
> Mesozoic may therefore have been somewhat different from scavenging today, 
> perhaps leaving fairly little room for medium-sized to small theropod 
> scavengers.
>
>> And what about the fluted beak of that Alberta ornithomimosaur ?? Perhaps 
>> these Mesozoic "vultures"
>> never needed hooked beaks .. just very sharp fluted ones.
>
> I'm not sure what you're referring to here? Are you talking about the 
> *Gallimimus* skull that was suggested to have filters? If so, I don't believe 
> it is considered to have truly been a filterer nowadays. In any case, it 
> seems like poor evidence for a dedicated scavenger and rather has a 
> discrepancy you'll have to explain. This goes for any 'flute-beaked' 
> ornithomimosaur as you yourself seem to note.
>
>> If this is anywhere near the truth then .. mesozoic palaeo art is indeed 
>> impoverished. Scenes of
>> scores or even hundreds of theropods battling over a large multi-ton carcass 
>> may have been the norm.
>
> Certainly sauropods weren't that huge. Note that you're suggesting scores of 
> multi-ton tyrannosaurs and *Deinocheirus* 'battling' here. Those critters 
> would have eaten a lot individually. The sauropods in *D.*'s ecosystem 
> weren't enormous but fairly modest-sized. Ol' Bigclaws itself would have 
> looked some in the eye and may even have grown taller.
>
>> There you go folks .. elephantine sized vultures .. or not.
>
> I'm afraid not, but thank you for prompting me to write to the DML for the 
> first time in years.
>
> Brian
>
>
>
>
>