Image: ©Science/PAINTING BY M. W. SKREPNICK, UNDER THE DIRECTION OF L. M. WITMER
Certain long-held views about what dinosaurs looked like need a face-lift, according to the results of a new study. A report published today in the journal Science reveals that the fleshy nostrils once envisioned as having been positioned high on the foreheads of some of these beasts instead belong just above their mouths. Though it might seem like splitting hairs, the finding could lead paleontologists to a better understanding of dinosaur physiology.
Conventional ideas about nostril placement date to the earliest discoveries of large sauropod dinosaurs, which early paleontologists thought dwelled primarily in the water. Upward-facing nostrils placed high on the forehead, they reasoned, would have enabled these giants to breathe when wading in deep water. Since then, however, researchers have determined that the sauropods spent most of their time on land. Yet the old nostril notion stuck.
To figure out where in the dinosaurs' huge bony nostrils the small fleshy nostrils should actually go, Ohio University researcher Lawrence Witmer turned to the dinosaurs' closest living relativesbirds, lizards and crocodilians. Scrutinizing the relationship between flesh and bone in these creatures enabled Witmer to map out the probable positions for dinosaur nostrils. "We looked at as many modern-day animals as we could get ahold of," Witmer explains, "and found an extraordinary amount of evidence to suggest the nostrils of dinosaurs actually were parked out front."
Witmer notes that the visual change is most striking for sauropods, such as Diplodocus (see image). But biologically, he says, "it'll make a huge difference for all kinds of dinosaurs." Up front, or rostral, placement of the nostrils would not only have given dinosaurs a better sense of smell, it may have conferred an important respiratory advantage. Indeed, such benefits may explain why the rostral nostril rule applies to almost all vertebrate animals.