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

["Larry Dunn" <larrydunn@hotmail.com>]

From: Chris Campbell <sankarah@ou.edu>

>The problem with that idea is that there *are* no modern analogs.  
These
>animals are so different in form that you can't really compare them to
>extant animals.

I'm not sure I accept the rationale that, because theropod dinosaurs 
weren't "configured" like extant vertebrates, that all bets are off and 
it's time to begin the wild speculation.  There are certain "rules" 
observed in extant vertebrates regardless of their configuration; if we 
are going to speculate about these animals (and, of course, we are), 
it's more realistic to use these rules than our imaginations.

>But you have to look at more than weight differentials.  You also have
>to look at likely hunting techniques, life history strategies, build,
>and so on.  All of these things are very different from those of living
>species, so we can't directly compare the two.

As a rule of thumb, pack-hunting mammals do not prey upon animals that 
exceed their own weight by more than a few multiples.  This is true of 
both wild dogs and lions, although the hunting strategies, body 
configurations, etc., of each are very different.  Assuming that 
dromaeosaurs were as active as mammals (a *very* generous assumption 
indeed), they would follow the same rules. 

>I just can't see a reason to think it's that remote, though.  Those
>claws couldn't have been used for anything other than slicing (they're
>too well designed for that role), and the dromies couldn't use them on
>anything other than big animals.

The dromaeosaur giant-killer scenario has repeatedly been called into 
question.  The utility of the claws for cutting is a matter of 
contention, and some have argued that the "hands" and forelimbs of 
dromeaosaurs with their limited range of movement were simply not suited 
to hanging onto a wildly bucking multiton herbivore.  In any event, even 
assuming away all of these problems, the physical challenge of holding 
onto a moving prey animal with forelimbs and kicking claw-equipped 
hindlimbs through the prey animal's hide seems almost insurmountable.
 
>  You've said it's ridiculous to think
>that they'd lose three of their number in an attack, citing modern
>mammals as evidence, but the comparison isn't valid.  Dromies layed 
eggs
>and lots of 'em; this might let large numbers of them survive to
>maturity, which would mean they'd be less likely to worry about
>individual survival. None of this proves a damn thing, of course, but
>it does make the hunting idea plausible.

First, how do we know that dromaeosaurs had large clutches of eggs?  I 
don't recall dromaeosaur nests having been found.

In any event, animals which lay large numbers of eggs do not do so 
because their young all mature, then die while hunting huge herbivores; 
they lay large clutches because infant mortality is very high.  It's 
simply impossible for vertebrates to invest the resources to have huge 
broods and then assure that they all survive.  (I'm not going to get 
into the external pressures that lead to these various repro strategies; 
it's been discussed here in past years.) It's one or the other; either 
have a few young and nurture them carefully or have a lot so that a few 
survive. 

>True.  Also, it's not unreasonable to assume that Deinonychus hunted
>Tenontosaurs with good success, and that the site under discussion was
>just a freak occurrence.  Heck, they might have killed it without 
losing
>a member and then got swept up in a flash flood or something.  

I've never really bought the idea that, because animals' remains are 
found together at a fossil site, that they were all hanging out together 
when they died.

But anyway, for reasons I've discussed before both in this and previous 
posts, I see no reason at all to assume that Deinonychus preyed upon 
Tenontosaurus, and very good reasons to assume they did not.

>A fair point, but we also have to remember such things as hunting dogs
>killing water buffalo, wolves killing bison and moose, lions killing
>elephants, and so on.  These are not unusual occurrences, so we have to
>keep an open mind about what the possibilities are, especially in light
>of differences in build, probably life history strategies, and 
armament.

I don't think that wild dogs (is that what you meant by "hunting dogs"?) 
generally kill water buffalo (sure, maybe there's some mutant pack 
that's doing it, but generally Water Buffalo are too big for lions to go 
after, let alone wild dogs).  And I think we have in fact agreed that 
the elephant-eating lion prides are *very* unusual.  The exception 
rather than the norm.  Probably better to use the norm to hypothesize 
about the behavior of extinct animals.

>But think about it: given that sickle claw,
>pack hunting would require no coordination at all.  All you'd need is a
>"scream and leap" mentality and a will for mayhem, and you could take
>down whatever you felt like.  Larger numbers just mean larger animals. 

This is the heart of the entire problem.  We need to avoid the 
anthropomorphizing of theropods.  What current predatory animal has "a 
scream and leap mentality"?  What current predator engages in "mayhem?"  
Why, none, I would say.  Predators just do not blindly hurl themselves 
at huge herbivores for the fun of drawing blood, then enjoy the carcass 
if they've survived and it's Miller Time; they carefully select prey 
based on likelihood of success and minimalization of risk.

In my humble opinion, the animals are actually more interesting when we 
see them with their likely natural talents and limitations rather than 
simply as scaly hitmen.

>But can we keep intrepid beetles?  :)

But of course.  What would life be without I.B.'s?

Larry

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