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

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

From: Jack <jconrad@lib.drury.edu>

>We should not *assume* anything about any extinct organism.  We should,
>however, weigh the evidence we are given with an open mind.  Evidence
>exists that at least some theropods moved in groups.  

What is the evidence of theropods moving in close proximity at the same 
time?  Assuming there is evidence, I assume there's no indication that 
they were moving *in a social group* (as opposed to several animals 
moving in proximity to one another -- there's a difference).  

Were an current Ora kill site to be preserved as a fossil, we'd probably 
find a number of tracks of Oras moving in on the carcass.  Maybe some of 
them were coming in from the same direction.  They weren't coming 
together as a group, however.  Nor did they  hunt the boar/deer/German 
philanthropist as a group.

>Evidence exists that
>extant theropods also move in groups, though they usually do not hunt
>together.  This may or may not be due to the fact that extant predatory
>theropods are no longer terrestrial. 

Birds don't really help us much here.  They are fairly specialized 
critters, very different indeed from Tyrannosaurus rex, and I'd be 
reluctant at best to draw any conclusion about the behavior of a 
terrestrial, hundred-pound early Cretaceous theropod from observed 
bahavior of an avian, five-ounce extant theropod.  Your average bird is 
also much smarter than was your average theropod assuming present 
analysis of intelligence is correct.

 Because we are certain that there
>were at least three dromies at the site of at least one dead 
tenontosaur,
>there is evidence that _Deinonychus_ either moved in groups or lived in
>relatively close proximity with one another.  

I also don't see how the discovery of three deinonychus preserved 
together at a fossil site indicates that they were together when they 
died.  What is there at the site to indicate this?  Let's assume that 
they were together when they died: does this suggest that they 
habitually traveled together? For instance, wouldn't small carnivorous 
animals normally leading separate lives be drawn to the same carcass?  

Assuming dromaeosaurs were pack hunters, and seeing your lion/elephant 
prey event example as an anachronism, shouldn't the packhunting 
dromaeosaurs be picking on someone their own size, or only a few 
multiples bigger?  Tenontosaurus wasn't vast but was still a pretty big 
fellow to be hopping on top of.

Shouldn't we be conservative in using the fossil record to draw 
conclusions about animal behavior?  We have a set of criteria for 
present pack hunters.  Using the fossil record as evidence, which of 
these characteristics do theropod dinosaurs possess?

>THEREFORE, if _Deinonychus_
>were predators, it is not beyond reason to suggest that they were 
>group
>predators. 

Deinonychus certainly seems configured for a predatory life.  Why does 
this lead to even the suggestion that they were pack hunters?  As we've 
discussed, bobcats aren't, monitor lizards aren't, and a multitude of 
other predatory animals aren't.  Only a *handful* of predators are.  On 
what do we base this possibility?  The presence of more than one corpse 
at a fossil site?

Cheers,
Larry


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