Do any other theropods besides Majungatholus atopus show evidence of openings for possible air sacs in their vertebrae, similar to those found in present day birds?
Yes, plenty of theropod dinosaurs (and sauropods!) have clear indications of air-spaces in their bones. The reason that this was widely reported when it was discovered in Majungatholus is that this animal is a member of rather a primitive theropod group, whereas air-spaces are much more often seen in more advanced theropods, including spinosauroids, allosauroids, and many coelurosaurs.
What's more interesting is that, because similar air-spaces are found in the vertebrae of sauropods, it seems likely that they were produced by the same mechanism in both groups. This suggests that the air-sacs in the soft-tissue that carry air to the hollow bones in birds (and other theropods) were in place at the time of the sauropod-theropod split. And the presence of those air-sacs in turn suggests that even the most primitive sauropods and theropods (and their common ancestor) likely had a bird-style respiratory system, with a flow-through lung. Now isn't that an impressive amount of conjecture to get from a few holes in some bones? :-)
Last edited by Mike Taylor (2nd Mar 2007 09:07:06)
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