[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Jobaria and the Elephant...

Mike Lovelace said, in relation to my comment on sauropods possibly breaking their bones if they fell with their forelimbs on a predator:
I am a little confused by this. As an example, when we (humans) perform a
push up, we are using the contraction of the Triceps (primary), and upon
descent from the apex of the maneuver we use the Triceps as a control
mechanism for a smooth descent. I don't know what the name to apply to this
other than a controlled relaxation of the Triceps group. I am not going to
argue behavior on rearing for defense, I have a preference to functional
morphology. I will say this, yes it could raise up, from a functional stand
point, the why is speculation at this point. As for any sauropod with a
structure capable of rearing, it would have a controlled decent, there is no
compelling argument to suggest otherwise (the gravity doesn't change, and the
acceleration of descent wouldn't overcome the control of a muscle group
strong enough to raise it in the first place). Thanks

We shouldn't compare humans with sauropods, although I see what you're getting at. All sauropods (except titanosaurs) have a reduced or absent olecranon process. What this means is that most sauropods had relatively vertical limbs most of the time. Their triceps muscle (probably a misnomer, since gators appear to have five heads for this muscle) would not have had the same sort of lever arm we see in graviportal mammals. You have an animal that already has a straightened out arm most of the time. Are you proposing that they bent it and then pushed off with it? From what I can tell, the bending of the forelimb wasn't very common.

We don't know for sure if sauropods could rear, in large part because we don't understand the biomechanics of these animals that well. In time, we may have a better answer to your questions, and others that have appeared on this list. For now, much is speculation or using the behavior of elephants to justify certain behaviors. As I have already noted, we must be careful when using analogs because there is a tendancy to carry these too far.

Hope this helps,

Matt Bonnan

Get Your Private, Free Email at http://www.hotmail.com