Feel free to pass the following on to the list if you'd like; I leave it up to you. Regarding sauropod necks . . . their posture is a lasting puzzle to me. Carrying the neck vertically means less muscular effort is required overall because the center of gravity of the neck is moved closer to the source of support. And yet Diplodocus and Apatosaurus seem to be terribly designed for carrying their necks efficiently. It really doesn't matter what one thinks of Parrish and Steven's DinoMorph work (which I happen to think is awesome); you can just eyeball the verts and see that simple mechanical interference is going to prohibit a very steep post for the neck (if you subscribe to Prehistoric Times, you've probably seen this demonstrated by HP Tracy Ford in his How to Draw Dinosaurs column). Now, if the diplodocids were rearing up, the horizontal pose would become a vertical one and much would be explained. However, I regard the rearing hypothesis with some skepticism until someone figures out a good way to test it. If the sauropods were standing straight-legged, the adductor musculature might prevent any serious elevation of the body. OTOH, I have a hard time believing that a 30-ton 'pod would support all that weight on two bent knees, a la Sereno's Jobaria mount. That would put Triceratops' elbow to shame! Finally, were the sauropods really rearing so much that their necks became optimized for that posture rather than quadrupedal locomotion? Good questions all, and I eagerly await the day when some enterprizing soul finds some empirical support one way or the other. It is not enough to observe the long necks of sauropods, do the math and figure out that a vertical posture is the most efficient in terms of muscular effort, and conclude that the vertical posture is accurate because it is the only one that makes sense (not that it hasn't been done often enough). As much as we might like to have sauropod necks and everything else in paleontology behave in accordance with our (current) logic, sometimes it just ain't the case. In this case, an argument based on logic alone is not a great way to test the hypothesis. The best way to test the hypothesis is by looking at the actual bones (not someone's drawings of them, although I'll take 3-D digital models in a pinch) and seeing if they can reasonably fit together in the pose in question. The only people that have done that for sauropod necks, AFAIK, are Martin (1987) and Stevens and Parrish (1999). And frankly, everyone else who has held forth on the subject, myself included, is talking out their ass. They (we) may or may not be correct, but if they are correct it has to be by accident because they haven't done any real testing. This may seem grim, but I find it exciting because I think that before too long more people will be using sophisticated 3-D modeling software, like Dinomorph, to test all kinds of hypotheses about dinosaur posture and locomotion. At the recent SVP's, we've seen the beginnings of what I hope will be an explosion of new biomechanical investigations of fossil animals using computer models, good extant analogues, and a phylogenetic perspective. I can't wait to see more. Best, Matt Wedel |