Re: rearing sauropods

["Steve Brusatte" <dinoland@lycos.com>]

On Thu, 3 Jan 2002 00:58:30   
 David Marjanovic wrote:
>> Every gen[us] of diplodocid has a different neck length, why if
>> they all eat from tree tops? Wouldn't they want to have a neck the same
>> length?
>
>This would lead to severe interspecific competition -- exactly amonng so
>many species of tree browsers different neck lengths should be expected.

Yeah.  This is a perfect example of evolution at work.  Just because two 
animals are feeding from the same tree doesn't mean that they should-or 
would-have exactly the same neck length (or teeth, or claws, or whatever).  I 
mean, this is Evolution 101.  Unless these diplodocid genera were evolving in 
completely different, insulated areas then there is no reason to expect them 
all to have the same, or even very similar, neck lengths.  If they did they 
would be competing for the same food resources, which, as David said, would 
lead to intense interspecific competition.  Intense competition is bad, bad, 
bad for survival.  

>> With the majority of weight around the hips would also make it easier for
>> the animal to walk, and turn for that matter.
>
>Why?
>Anyway, it would also make it easier to rear, no?

Although I hate even discussing it anymore, this situation reminds me of the 
obligatory and now tedious "T. rex scavenger" debate.  I'm sure Tyrannosaurus 
scavenged at times, as most carnivores do.  The question is whether or not it 
played a major role in its feeding strategy.  Based on Sereno's papers and the 
book HP Longrich mentioned, it seems reasonable that some sauropods could rear 
up.  But, did rearing up play a major role in the sauropod(s)'s life (i.e., was 
it a major feeding adaptation, was it used for mating, etc.)?  As we have 
discussed, elephants CAN rear, but usually it takes quite a bit of urging from 
a circusmaster, clown, or zookeeper.  I don't know of any fossilized Jurassic 
clowns, so the big question is whether sauropods regularly used rearing as an 
integral part of their survival.  I doubt this will easily-if ever-be known.

Steve

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