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Re: (sigh)sauropod necks again--long! -Reply



Toby:

Thanks for the reply.  You said:
"The benefit from rearing up has to be quite high because the price
of falling would be steep.  It's the tumbling T. rex problem in
spades.  A mouse can fall many times its height.  A human can usually
fall its own height, but not always (I dislocated an elbow once that
way).  A sauropod?  Don't even think about it.  If it reared up, the
mechanism would have to have been be nearly 100% stable and the
benefit very high or the behavior simply wouldn't have been worth the
risk."

I agree.  Sauropods appear to have had larger cartilaginous caps on
the ends of their long bones and wrist bones.  We ascertain this
because of the very pitted and rugose texture at the ends of sauropod
long bones and wrist/ankle bones.  Rugose bone is formed by bone
growing up into the cartilaginous cap of hyaline cartilage.  A general
rule of thumb (although in no way a given or easily defined rule) is
that the more rugose texture a long bone may have on its ends, the
thicker the cartilaginous cap.

However, hyaline cartilage can only get so thick before its
force-distributing properties are compromised.  So while sauropods had
relatively thick cartilaginous caps at their limb and wrist/ankle
joints relative to other dinosaurs, they could only have been so thick
with only so much force-distributing properties.

A sauropod dropping down onto its forelimbs after rearing may have
been in danger of rupturing or squashing (and thus killing) its
cartilaginous joint caps.  IF sauropods reared THEN it seems more
likely they would have had a more controlled descent back on to their
forelimbs.  But what muscles controlled this?  How do we look for
evidence of them on sauropod skeletons?  

Hmmm ...

Matt Bonnan