Re: PACK HUNTING, SHMACK HUNTING...

[Chris Campbell <sankarah@ou.edu>]

THis will be my final post on this topic (I promise!).

Brian Franczak wrote:
> 
> In response to Larry Dunn's statement:
> 
> >> A lion whose jaw has been broken by a zebra was essentially killed by
> >>the zebra.
> 
> Chris Campbell wrote:
> 
> > 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.
> 
> The entire argument for "pack hunting" is based on the site featuring three
> dead _Deinonychus_ and one dead _Tenontosaurus_, the proposed scenario
> being that the tenontosaur somehow killed the three dromaeosaurs while they
> were in the midst of attacking it. How does this jibe with your statement?

It is?  I thought it was based on the fact that 20% or so of all
Tenontosaurus material is found with Deinonychus teeth.  Since
Tenontosaurus is 4-5 times larger than Deinonychus on average, pack
behavior seems to me a reasonable explanation for the association.  I
suppose the relationship could be somewhat like that between tigers and
elephants in south Asia, but that seems less likely to me.
 
> Larry wrote:
> 
> >> 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.
> 
> To which Chris responded:
> 
> > 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.
> 
> I'm not sure your description of _Tenontosaurus_ is accurate. First, you
> have no idea how fast or slow _Tenontosaurus_ was in life. 

Quite true.  However, I would posit that it's safe to assume Deinonychus
was much faster.

> Second, it most certainly had a beak and a long tail that could 
> conceivably be used as defensive "weapons" against attackers. 

I think this is very unlikely.  First, the beak was U-shaped, suited for
cropping vegetation but nowhere nearly as effective as a ceratopian's
beak might have been in defense.  Further, the tail was stiffened to a
large extent, making it difficult to use as a weapon.  Yes, it's
conceivable, as many things get used as weapons in desperation; however,
I think attacks with the forelimbs (which are very robust) are much more
likely.

> And while it didn't have mammalian hooves, it did have blunt claws 
> on its hind feet. 

True.  I'm not sure kicking would be much of an option, though.  It is
not built like a horse, after all.

> The most bizarre aspect of your scenario, however, is the idea that 
> because it was "defenseless" (your opinion), what, it just stood 
> there and let itself be eviscerated? It didn't try to run away, or 
> do *anything* to protect itself? This seems a bit absurd (that word 
> again...).

No, I imagine it certainly tried to run away.  I imagine they probably
lived in herds to reduce the chances of being hunted.  I also imagine
that Deinonychus would likely only try for juveniles, since (as John
Ostrom pointed out) the fully mature Tenontosaurs were likely too big. 
Mass is effective as a defense, and I think the larger Tenontosaurs
probably relied on that to some extent, along with herd behavior.
 
> Chris wrote:
> 
> > 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.
> 
> One minute you have them leaping on and off the tenontosaur in a
> ballet-like frenzy, the next they're so inept that they can't leap off
> their toppling prey in time to prevent themselves from being crushed to
> death...

True.  Being crushed is probably out, now that I think about it. 
Trampled by other members of the herd, perhaps?  Some freak accident? 
There's nothing to explain it, really, no matter what view you adhere
to.
 
> Here's the real problem I have with this site (and the supposed explanation
> associated with it): There are three dead _Deinonychus_ and one dead
> _Tenontosaurus_. In order for all four of them to have been found together
> in the proposed "pack-hunting" kill scenario, the three theropods HAD TO
> HAVE BEEN KILLED ON THE SPOT, dropped where they stood, AT PRETTY MUCH
> EXACTLY THE SAME TIME AS THE TENONTOSAUR. All four of them, three predators
> and one prey animal, brought down in the same place at pretty much the same
> time. What are the odds of that? The theropods didn't die of injuries
> sustained in the attack: they would have wandered off to die. The
> tenontosaur wasn't on the run, but standing it's ground, else why would the
> dromaeosaur remains be right there with it? So the attack is taking place
> in one spot, the prey, standing its ground, kills three of its attackers
> and is then immediately killed itself. Does this make sense? And if you
> want me to believe that the tenontosaur simply fell on the dromaeosaurs,
> the question then becomes, why *didn't* the predators leap off before being
> crushed to death? By your own earlier scenario, Chris, they weren't on for
> a ride, they were leaping on-and-off quickly. Sorry. You can't have it both
> ways.

I think the main problem with this site is that it can't be adequately
explained no matter what view you take of things.  Let's assume that the
Deinonychus weren't hunting the Tenontosaur; how, then, did all of them
die?  There's no reason to think the Tenontosaur killed the dromies; if
they're not hunting it, that explanation gets tossed.  How, then?  Did
they kill one another?  That's about as far-fetched as them being
crunched by the Tenontosaur.  No matter how you look at it, this site is
weird.  
 
> Larry wrote:
> 
> >> Were there no lizards to eat?  Smaller dinosaurs?  Mammals?  Seems
> >>rather fantastic to me.
> 
> To which Chris replied:
> 
> > Uh, they were grabbed by the myriad other small predators running around.
> >> Particularly the really fast ones.
> 
> Bad argument. I realize that the fossil record is woefully incomplete, but
> please name "the myriad other small predators" found in _Deinonychus_'
> environment. Granted that there is the likelihood of their existence, but
> your statement is based on specious reasoning, I think. Isn't it just as
> likely that *_Deinonychus_* was the smallest predator in its environment
> and we simply haven't found all the larger forms yet? 

Oh, come on.  What about the various coelurosaurs running around?  The
ornithomimids?  Other dromaeosaurs?  These groups were active throughout
the Cretaceous, and members of each group were certainly contemporaries
of Deinonychus.  Lizards, eggs and mammals would be perfect food for
members of these groups.

> And let's remember that wolves, despite a "myriad other small predators",
> manage to subsist on mice and other small mammals when they have to; 
> they don't eat caribou, moose and bison exclusively.

Let's remember that wolves *do* hunt moose, caribou and bison when they
can.  Speaking strictly in ecological terms there's no reason
Deinonychus wouldn't take the largest prey it could safely manage, just
as wolves do.  I expect it certainly made do with lizards and mammals
and eggs and whatever else it could lay hands on when it had to, just as
wolves make do with mice and berries when they have to.  I see no reason
to assume it only scavenged Tenontosaurus, though, particularly since
some 20% of all Tenontosaurus finds have Deinonychus teeth associated
with them.  Nothing is that particular about meals it *scavenges*.
 
> The pro-"pack-hunting" arguments, unfortunately, have become more and more
> flimsy as this discussion goes on (can we leave inapplicable schools of
> fish out of this please!), and the inability to even cede the point that
> there might  *possibly* be another viewpoint on the issue does nothing to
> help make them more credible. 

I've ceded that point from the beginning.  In fact, I've gone out of my
way to make it clear that I was arguing that pack hunting was
*possible*, perhaps even likely, and by no means a definite thing.

>The fossil evidence for "pack hunting" in _Deinonychus_ (or any other 
>theropod) is debatable at best; looked at dispassionately, it does *not* 
>support the idea. 

If you would kindly explain the presense of Deinonychus teeth in so many
Tenontosaurus finds, then, I'd be more likely to dismiss the idea.  What
we know is this: Deinonychus interacted in numbers of three or greater
on at least some occasions (whether to fight or hunt or whatever, we
don't know) and Deinonychus had a taste for Tenontosaurus flesh.  We
know it is arguably possible that they could physically attack an animal
larger than themselves, and we know that even such things as spiders can
hunt cooperatively in some circumstances.  This indicates to me that
it's certainly *possible* that Deinonychus hunted Tenontosaurus in
packs.  The evidence available does not invalidate this idea, but
there's not enough of it to really support anything, IMO.  

> Also ignored is the fact that the "sickle claw" did not appear overnight 
> in _Deinonychus_, and must have evolved over a long period of time, just 
> as likely for a purpose other than the commonly depicted, highly-suspect 
> "meat slicer" we all know and love. 

And the claw would be increasingly useful in an offensive capacity as it
grew, just as with the enlarged canines of extinct sabre- and
dirk-toothed cats and their relatives in recent times.

> Stan Friesen's notion of "tree-climbing" is just as good an
> explanation for the claw as "terminator". (Better, IMHO)

No, it's not.  The design of the claw suggests it would be very poor for
climbing trees; such an aid would be much more robust if that were its
primary purpose.  The claw is ideally designed for a piercing function,
a design perhaps augmented by sexual selection.  Whether it was used in
an offensive capacity is another issue, of course.
 
> An awful lot of proposed behaviors for dinosaurs have been bandied about
> over the years, a lot of them now defunct or questionable. F'rinstance...

Agreed, but these go both ways.  It seems every therapod is being called
a scavenger these days, and the notion gets to be too much at times.  If
Tyrannosaurs were scavengers and Deinonychus were scavengers and
Coelurosaurs and Ornithomimids only went for eggs and small mammals, who
killed all of these large herbivores?  Someone had to kill them all if
everyone's scavenging on them, but the main candidates are now
scavengers!  Maybe they just had the courtesy to die at a set time, thus
providing a fresh source of carrion for all of our therapods on a
regular basis.  Awfully nice of them.

> Do we still believe that sauropods had to live most of their lives in water
> to help buoy their massive bodies? Or that pachycephalosaurs butted heads
> like mountain goats in rut? What about the "fact" that dinosaurs, like
> their reptile relatives, simply abandoned their eggs immediately after
> laying them? The list goes on. "Pack hunting" in theropods, long since
> spread far beyond the original find of _Deinonychus_ that inspired the idea
> (to encompass most other theropods it seems) is another such theory in need
> of closer scrutiny.

As is the notion that therapods couldn't have operated in packs, or the
notion that they couldn't have hunted large animals.  I understand that
you don't want us to get carried away, that that's fine; there is such a
thing as going too far, however.