Tuesday, 9 December 2008

Airheads!

A study by Lawrence Witmer and Ryan Ridgely at the University of Ohio has just been published in which they discuss the results of using CT scanning techniques on dinosaur skulls to map the air cavities and speculate about the effects of all that air inside the skulls. This link to Palaeoblog is where I picked it up from, but that just takes you to the top of the blog, not to the actual post. I don't know how to do that.

It's long been known that beasties like T. rex had reduced bone in their skulls in order to maximise lightness while maintaining strength. Everyone familiar with their skulls will remember the gaping holes and remember why they're there.

Turns out, previous CT studues had been focussed on the bones and muscles, without really considering actual air spaces (as opposed to absence of bone), which turn out to be rather more extensive than previously thought. eg the fleshed up head of T. rex was 18% lighter than it would have been without all the air. And since it weighed in at around half a tonne, that's a saving worth the effort!

Something I'd not expected, however, was a casually-dropped aside in the course of discussion of ankylosaurs. These have been known for a long time to have had extensive and quite convoluted nasal passages:

“Not only do these guys have nasal cavities like crazy straws, they also have highly vascular snouts. The nasal passages run right next to large blood vessels, and so there’s the potential for heat transfer. As the animal breathes in, the air passed over the moist surfaces and cooled the blood, and the blood simultaneously warmed the inspired air,” said Witmer. “These are the same kinds of physiological mechanisms we find all the time in warm-blooded animals today.”

Did you spot that? ... mechanisms we find all the time in warm-blooded animals today. I didn't know ankylosaurs were warm-blooded. Did you? Or am I just over-extrapolating?

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