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Re: Theropod bluff & hunting (was re Dilophosaurus Forelimb Bone Maladies
On 04.03.2016 17:59, Mike Habib wrote:
I would flip this on its head: big cats, as high power precision biters, are
unusually well adapted to kill large prey. That's why cats do so much more
often than other living mammalian predators.
Well, I think its obvious I’m with Bakker on this one.
Also I think most mammals could be described as high-power biters, but
this is another adaption born out of necessity; they cannot usually
afford to lose teeth, so their teeth had to become relatively robust,
which in turn means they aren’t effective at filling the roles of
D’Amore’s works are one of the main sources for the analogy between
theropod and komodo dragon dentitions. I think in his dissertation he
made it quite clear that he envisions them to have functioned in a
Most varanids, some of which have teeth that are also good matches for
theropods, are obligate small prey hunters (they cannot cut effectively with
their teeth). Komodos are the exception, and their ability to carve muscle is
not so much a matter of their teeth as it is a special form of cranial kinesis
that allows them to saw with the jaws (see work by Domenic D'Amore).
Yet they still closely follow the trend observed in other animals; Great
whites can also take Elephant seals and right whale calves.
Most sharks are also small game hunters. Even large adult great whites mostly
hunt juvenile pinnipeds that can be consumed in a bite or two.
Hayward & Kerley 2005 cite Scheel (1993) as confirming that only 25% of
kills in the Serengeti are juveniles, and go on to estimate the
preferred prey sizes of African Lions at over 200kg.
The adults are unusual prey
Hayward, Matt W., and Graham I. H. Kerley. 2005. Prey preferences of the
lion (Panthera leo). Journal of Zoology 267: 309–322.
But that’s the point, it also occurs in predators that are not big cats
and have none of their peculiarities. Those animals do it by entirely
different means and succeed all the same.
Yes, there is enough footage to show that this occurs, but that doesn't mean
it's common. And that's for big cats, which as already noted, are unusually
well adapted to kill large prey. (Much more so than a theropod).
I’m afraid that’s not the way I’m referring to it. I was specifically
referring to the findings of Rayfield et al. 2001. These seem to clearly
corroborate Bakker’s earlier hypotheses about _Allosaurus_, even if the
details have been subject to some disagreement.
That depends on how we measure strength. Tyrannosaur skulls are truly strong in
the way I think you're referring to.
Because they didn’t need them, the most efficient way to avoid injury
from prey is to avoid prolonged physical contact. Cats don’t do it
because their teeth aren’t suitable for bite-and-let-go behaviour, but
every predator that hunts large prey with teeth that are remotely
analogous to carnosaurs does.
But they don't have a great number of particularly specific reinforcements to
twisting or even compressive loads along the dorsal margin of the skull.
You implied that komodo dragon skulls are specifically adapted for
flesh-tearing, and I certainly won’t argue with that, in fact I think
certain theropods display analogous adaptions, but that is where you
Are the same features present in other varanids and just go completely
unused? Otherwise, looks are just deceiving.
The jaws of small prey specialists can actually look a lot like those of
related large prey capable taxa. Varanids are a good example, as are cats.
Primarily shallower, more gracile, and also proportionately smaller,
with additional differences in tooth morphology (often adaptions for
handling and restraining small prey, as is present in _Dilophosaurus_).
And less optimized for handling loads than _Allosaurus_ or the like,
which may or may not be visible, but will surely be detectable using
Finite Element Analysis.
E.g. Spinosaurs have shallow skulls, inferred to have had relatively
less resistance to bending. Their teeth have lost much (Baryonychines)
or all (Spinosaurines) of their cutting function. And direct evidence of
predatory interactions and diet supports a diet of fish, pterosaurs and
juvenile dinosaurs, so they fit the presumed niche of "small-prey
specialist" nicely on every account. I am also not aware of any
spinosaur bite marks on large dinosaur skeletons, or spinosaur skeletons
with peculiar pathologies inferred to have been directly or indirectly
caused by a large animal (while what there is are foreign bodies from
sawfish stuck in their jaws). Your previously used analogue of a stork
is quite fitting here, although I must say I highly disagree with
comparing _Allosaurus_ to a stork.
Actually, this raises an interesting question for discussion: what do we
predict that a small prey adapted theropod skull should look like, and what
should a large prey specialist skull look like? I suspect we have different
What would be your prediction?
Not if they are healed. The others, sure, but the question is how much
rigour is in such statements or whether they just feel like they are
making less of a bold statement if they assume scavenging than if they
True. But bite marks are often interpreted as carrion feeding traces.
Certainly intraspecific combat is a potential explanation, but if they
were so adept at causing injuries to conspecifics, and so willing to
engage in risky behaviour, it seems strange they would absolutely avoid
killing a similar-sized herbivore.
I disagree; living birds often injury each other during intraspecific combat,
for a start.
It’s probably more difficult for a lion to catch a gazelle than it is to
catch a buffalo.
I'm not sure why that would be difficult.
Yes, but the niche I’m referring to isn’t a hypothetical permutation. It
is one that seems to be filled in every extant ecosystem.
Living taxa don't fill every ecology that we can come up with. True niches are
not all available permutations.
I fully agree that it is a dominant trend, but using a variety of
adaptions and techniques (others apart from doing it like a cat) extant
top predators are by no means limited to juveniles and small prey as you
seem to imply theropods were.
Everything from cats, to canids, to bears, to varanids, to extant
theropods, to delphinids and lamniforms at least occasionally kills prey
its own size or larger. Theropds in general, as well as carnosaurs are
among the most successful major predatory taxa ever, and they absolutely
dominated terrestrial predatory niches of the mesozoic with very few
exceptions. So from a purely parsimonious standpoint, it’s nothing
far-fetched that I’m suggesting here (and sure enough it has been
suggested quite frequently).
That's a good point, but since juveniles are still preferred in the modern
world, I'd consider that to be the dominant trend.