Wednesday, May 27, 2009

Put Your Heads Up For Detroit!

A quick note on a new paper out today on sauropod anatomy. Always exciting stuff, obviously, but today especially so.

As many of you may have heard, the days of sauropods with their heads held high and proud came to a crushing end in 1999, when Kent Stephens, using his DinoMorph computer anatomy program, found that contrary to decades of portrayals in art and museum mounts, sauropods did not carry their heads much higher than their shoulders. The neutral pose of the long neck was found to be that of a vertical beam, dipping towards the ground to mow down field after field of ferns, not a high, swan-like S-curve.

Enter the SV-POWsketeers, the new guard of sauropod experts who made a splash a few years back by starting a collaborative blog about nothing more than Sauropod Vertebrae (Pictures Of the Week, hence the acronym).

In thier first formal paper as a team, the SV-POW! guys became the first to really challange Stephens' findings, which had by now become the orthodox view, represented in such pop culture icons as Walking with Dinosaurs. Stephens stated in his paper that no modern animals normally held their necks out of neutral pose, except to drink, display, etc. When just walking around, they were, as Zapp Brannigan said with disdain, "So beautiful, yet so neutral."

But, were they? And are they? According to the SV-POWsketeers, who looked at living animals from all major tetrapod groups using X-rays and studies of the existing scientific literature, no. Living animals never walk around with their necks in a neutral pose. In fact, far from being disgustingly neutral, the normal position for most animals is to flex the head and neck as much as possible! Doing this to sauropods means that (barring any unusual, unknown specilizations, like pressurized air sacs in the neck), not only can the poor things reach the ground to drink, they walked with heads held high, able to browse from the treetops as traditionally depicted without having to rear up onto two legs (though they could do that too, at least the diplodocids).

Note that this still rules out the traditional swan-curve. Everybody seems to agree that the neck vertebrae acted sort of like a long, rigid pole that would have been straight along the whole middle section, just bent severely at the base of the neck and at the head.

Read more about it in the scientists' own words over at SV-POW!

[Images used above are of Diplodocus carnegii, from Walking with Dinosaurs and SV-POW, copyright the BBC and Mark Witton, respectively.]


1 comment:

  1. "Rules out" the swan-pose is an exaggeration; "does not support" is more like it. It's possible that sauropods, like swans, bucked the trend and habitually curved the middle of their neck - it's just unparsimonious to assume so.