for National Geographic News
A new study suggests that anyone who sits down to draw a detailed picture of what dinosaurs may have looked like will have to tweak the nose a bit to get it right.
Usually the flesh-covered nasal passages of dinosaurs are shown toward the back of the openings in the nose bone.
But Lawrence Witmer, a paleontologist at Ohio University in Athens, Ohio, says that's wrong, and the nostrils were really much closer to the front, just above the mouth, and were larger than thought.
The finding, which Witmer reported in the August 3 issue of Science, is significant not just because it changes our idea of what dinosaurs looked like. It also has implications for how dinosaurs breathed, smelled, and regulated their body temperature and water loss.
"I don't know why we got it wrong for so long," said Witmer. "In general, the fleshy nostrilthe opening into the nasal cavityhas escaped scientific inquiry."
People have relatively small bony nostrils, so there's little doubt about where the flesh-covered nasal passages can be located to effectively do their job. The bony noses of dinosaurs, however, could have been more than two feet (0.6 meters) long, which leaves the placement of the fleshy nostrils open to interpretation.
Witmer said traditional views of the nostril placement are probably rooted in a historical belief that the huge, long-necked sauropod dinosaurs were amphibious. In that case, nasal passages positioned further back on the head would have worked like a snorkel.
Evidence uncovered in the 1970s suggested that sauropods were not aquatic, but landlubbers. Yet for some reason, the early depictions of sauropods with nostrils further back on the head didn't change, and that position was also picked up in renderings of other dinosaurs.
Witmer undertook the study because he is interested in the overall physiology of dinosaurs. He was curious about why the fleshy nostrils of dinosaurs were shown where they are, but he couldn't find an explanation.
So he set out to get a more accurate idea of just where a dinosaur's nose was probably positioned. He did X-ray examinations of living birds, crocodiles, and lizards, which are thought to be surviving relatives of dinosaurs.
He painted the fleshy nostrils of the animals with latex and sprinkled the painted parts with barium sulfate so they could be seen on X-ray film. This allowed him to examine the position of the fleshy nostrils in relation to the bony nose structure.
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