Re: The absurdity, the absurdity (was: Cooperating theropods?)

[Chris Campbell <sankarah@ou.edu>]

Larry Dunn wrote:
> 
> From: Chris Campbell <sankarah@ou.edu>
> 
> >> Surely you're not saying that cheetahs and wolves are basically the
> >> same animals because they both suffocate their prey?
> >
> >No, I'm not.  I'm saying that what they can go after is limited by the
> >fact that they have a given method of killing their prey.  They have to
> >be able to a) chase it down and b) apply that strangulation/suffocation
> >bite.  Deinonychus had a totally different method of killing its prey,
> >so the constraints we see in modern animals just don't apply.
> 
> This is presumably based on the presence of one large claw on each
> hindlimb.  

And a smaller brain, and differently oriented eyes, and a bipedal
stance, and arm-like forelimbs, and a totally different jaw structure,
and a host of other things.  The claw is the capper, not the whole
shebang.

> But that does not follow, because the large claw could have
> been used to disembowel small animals or to sever the arteries of
> somewhat larger animals as may have been happening in the Tugrugeen
> fossil.

The Tugrugeen fossil shows a Velociraptor who seriously miscalculated. 
There's no way that could be the norm, because that fella was doomed
from the get-go.  That claw would be overkill on just about anything
under a quarter ton; you can *bite* anything smaller to death with no
problem, as shown by the innumerable other small therapods running
around.  Critters the size of Deinonychus don't need better methods to
kill small prey; being able to kill larger prey, however, would open up
an ecological niche previously unexploited.  A sickle claw might well
have enabled them to do just that.
 
> >> Why's their "potential prey" so big?
> >
> >Assumming we're talking about Tenontosaurus, here.
> 
> Yes, but why assume active predation on Tenontosaurs?  Only a few
> species of mammalian predators hunt animals larger than they are.  All
> other terrestrial vertebrate predators hunt smaller animals with great
> success.  Does the single large claw on each foot throw out the rules?

In a word?  Yes.  Look at all the other small therapods running around
at the time.  How much of an edge would Deinonychus have in snapping up
lizards and such?  About zip.  In fact, the claw might even get in the
way.  Large cats and packs of dogs hunt large animals for one very good
reason: because they're there, and no one else hunts them.  All they
have to compete with is the few other animals also in their league, and
that's managable.  

> Particularly with respect to an animal which fairly clearly did not have
> adequate intelligence to behave cooperatively with other members of the
> species?

As I've said, killing a Tenontosaurus wouldn't require much in the way
of cooperation.  I jump, you jump.  I jump, you jump.  I jump, you
jump.  Not very complex.  

But that aside, I seem to recall hearing that they might not have been
as dumb as previously assumed.  Studies in birds today show that they
use their brains in very different ways than mammals do; IOW, they do
more with less.  African Greys have been equated with chimps in
intelligence, and they have pretty small brains.  If the same was true
with small therapods, they might have been capable of some serious
coordination.  Even if they weren't, though, the strategies we're
talking about aren't that complicated.
 
> >> There's no comparison between the forelimbs of a felid and the
> >> forelimbs of a dromaeosaur.
> >
> >I never said there was; I just noted that some extant predators don't
> >have any trouble holding onto a prey animal, even while it's moving and
> >bucking around.
> 
> Yes, and that's because their forelimbs are suited for it.  Unlike those
> of Deinonychus.

I'm still not convinced.  See GSP's rendition in D:tE.
 
> >>catch a hold with those extremely avain forelimbs (somehow),
> >
> >Forelimbs with sharp claws.  Again, see GSP's illustration in TDE.
> 
> They could have had razors issuing from their forelimbs and that doesn't
> change the basic fact that dromaeosaur forelimbs weren't really suited
> for grasping and holding on to a moving animal.

Look at the picture and get back to me on this.  If you hook the claws
on a nice, prominent spine holding on might not be so difficult.
 
> >>Probably draw the attention of the tenontosaur so it could turn around
> >>and squash the pipsquak who had such nerve as it fell off.  As you
> >>know, herbivores don't take being preyed upon lightly.
> >
> >Yeah, but unless they're Buffalo they usually can't do much about it.
> 
> Buffalo are not the only predators that defend themselves successfully.
> Many do.

Buffalo, bison, moose, elk, caribou, the occasional (brave) wildebeest. 
Elephants.  All but one big guys with horns.  The last has tusks
instead.  What do hadrosaurs have?  Zip.  They're just big, and not very
threatening.
 
> >Also notice that predators are pretty good at taking punishment; we've
> >all seen the Discovery channel shows wherein a lion or cheetah attempts
> >to tackle a wildebeest alone, gets tossed all over creation, and
> >finally gets thrown off, tossed, trampled, or whatever only to get up
> >bewildered and wiser but otherwise unharmed.
> 
> Predators have to be in top shape to hunt successfully.  Small injuries
> can often be fatal to them, let alone major ones.  

Which is why I say they're very sturdy.  They don't get injured easily,
especially the more robust ones.

>A lion whose jaw has been broken by a zebra was essentially killed 
>by the zebra.

Hey, that's not a small injury.  You're missing the point here; it's a
given that injuries will take the animal out of commission, but what I'm
saying is that it's not that easy to injure one in the first place. 
Something like a trampling or goring or kick will do it, but
Tenontosaurs don't seem to me to be equipped for such attacks.
 
> >So the Deinonychus leaps onto the Tenontosaurus, gouges it with the 
> >big claw, hops off to scamper away while the Tenontosaur turns to 
> >deal with its tormentor, only to set itself up for a similar attack 
> >from the other side.  Heck, this wouldn't even require any coordination;
> >just pack members tackling whichever side didn't have a bucking head 
> >attached.
> 
> The scenario you describe takes a lot more coordination than most
> *mammalian* predators employ!  

Uh, mammals use lures, stealthy approaches, ambushes, decoys, precision
wounding, specific patterns of movement, and on again off again shifts
in their attacks.  Unless you exclude all dogs, social cats, and hyenas
from "most *mammalian* predators" the scenario I describe doesn't even
come close to being coordinated.  If you do exclude those animals,
what's left isn't social enough to count.

>And I'm not as enthusiastic as you to adopt such a meat-on-the-table 
>view of a large herbivore.  Because they don't eat meat doesn't mean 
>that they're not aggressive, especially in defending themselves.  

I don't view them as meat on the table unless they have no defensive
armament and aren't built for speed.  In every single animal we have
today which defends itself you see defensive weaponry; horns, antlers,
hooves, tusks, *something*.  T. had nothing whatsoever.  No bite to
speak of, no weaponry, not even any hooves.  Not even mass.  That sucker
*was* meat on the table.  

>Even assuming for the moment that the killer raptor rationale for 
>the dromaeosaur/deinonychus site is correct, it seems that 
>tenontosaurus was prefectly capable of defending itself.

Says who?  Who says the Deinonychus killed weren't killed due to their
own ineptitude?  The Tenontosaur doesn't get points if it killed them by
falling on them.
 
> >Tell that to wildebeest.  Five hundred thousand are born every year in
> >the Serengeti, and the population is quite stable.  That means five
> >hundred thousand, out of a population of a *million*, die off every
> >year during the annual migration.
> 
> You're agreeing with me.  All animals suffer massive attrition away due
> to a variety of factors.  Lions lose many of their cubs too.  The odds
> are against young and adult animals of every species.  So why then would
> dromaeosaurs engage a prey species capable of killing three of those
> precious few survivors in a single feeding event?  

Because unlike the wildebeest (who lose members due to migration every
year) the Deinonychus might not have lost many of their young due to
seasonal cycles.  The wildebeest lose their members from the adult and
subadult population; the juveniles haven't been born until the end of
the migration.  It's adults, fully grown wildebeest, 500,000 of them,
who are killed off each year.  

If you can keep your breeding rate up and have lots of other competitors
for smaller food, why not go for big prey?  If you have lots of kin, why
not take some risks?  It's better than being outcompeted for the smaller
stuff.

>Were there no lizards to eat?  Smaller dinosaurs?  Mammals?  Seems rather 
>fantastic to me.

Uh, they were grabbed by the myriad other small predators running
around.  Particularly the really fast ones.
 
> >And let's face it, if they weren't terribly bright and didn't use
> >sophisticated methods to hunt, how much training do they need?
> 
> Assuming these things, they presumably did what other small,
> not-very-bright predators did (and do) -- they hunted alone and ate
> things smaller than they were (large claws notwithstanding).  

Kinda makes the claws pointless, wouldn't you say?  What is is that you
have against a precocial pack predator?  

>Hunting animals larger than you requires both intelligence and sophisticated
>hunting strategies.

Yes, now.  We have no idea whether or not that's a law applicable to all
types of life.  And why dont' pirahnas have any problems, eh?  The force
of numbers strategy does work; we don't see it now because our modern
predators are stuck on large brains.  Dinos might have made use of it to
good effect.
 
> >>We can't want killer raptors so badly that we lose sight of this.
> >
> >Agreed.  And we can't want to tear down the image so badly that we lose
> >sight of other options.
> 
> "Other options" should not include basically describing an animal
> starting with a tabula rosa because it has large claws on its hind legs.

It's not.  It also includes analogues to modern predators (other than
cats and dogs, btw) and fossil finds.

> This had led you to invent a creature that hops atop it's prey's back
> and slash with hindclaws notwithstanding the unsuitability of its
> forelimbs for such grasping; 

According to you.  GSP's painting makes a pretty convincing case to the
contrary.

>an animal that sort of cooperates without cooperating, 

Which is done so often in modern animals (most especially non-mammals)
it's truly staggering.

>incidentally adopting (systematically!) an incredibly
>elaborate strategy-that's-not-a-strategy.

Incredibly elaborate?  Please explain how slashing at a flank not
defended by a bellowing head is incredibly sophisticated.  You could do
that with the simplest behavioral conditioning, pure instinct.  Jump on,
slash a few times, jump off when the head tries to bite you.  Repeat. 
This is *not*, by any stretch of the imagination, an elaborate strategy.
 
Chris