Dinosaurs Given a Nose Job to Reflect New Earthy Image
Scientists long have suspected that dinosaurs were land animals. Only recently, however, have the giants of the Earth been depicted as the terrestrial creatures they were.
To get a true picture, a small but significant change needed to be made in the dinosaurs’ appearance.
They needed a nose job.
A study by Ohio University paleontologist Lawrence Witmer found that the traditional depiction of dinosaur nostrils was wrong. They were placed too high on the snout, reflecting the old, erroneous notion that dinos lived in the water and used their noses to probe for air.
Published today in the journal Science, Witmer’s study corrects the classical picture. Using fossil remains and X-rays of the dinosaurs’ closest living relatives, the study concludes that the creatures’ fleshy nostrils were further forward and closer to their mouths. As with most other land animals, the placement better equipped dinosaurs to smell and to warm the air they inhaled through their nose.
The study gives us a better understanding of how dinosaurs ate, breathed and sensed their environment. The work also reveals a striking and unexpected similarity in the way nostrils are positioned on many animals, including humans.
When the first dinosaur bones were discovered in the 1880s, paleontologists speculated that the immense brontosaurs--even larger than whales--could not possibly have supported their weight on land and must have been aquatic.
The scientists depicted the fleshy nose holes high on the face, reasoning that the brontosaurs must have used their nostrils like snorkels when submerged.
Witmer began his work with a project called DinoNose, in which he studied fossil bones of dinosaurs and found evidence of a complex structure of soft tissue within the nose. These blood vessels and membranes served as air conditioner, humidifier and filter. The soft tissues left faint imprints on the bones, called “bony signatures.â€
Witmer realized that the classical nostril position, pointed upward, would have led air into a cul-de-sac, bypassing the soft tissue. This didn’t make sense. So Witmer decided to reexamine the nostril position.
“Dinosaurs give us the hard parts,†Witmer said of the fossilized bones he studied. But without dinosaur soft tissue, there is no way to guess where the fleshy nostrils lay. Witmer turned to the dinosaurs’ closest living relatives: birds and crocodiles.
Using X-ray techniques, Witmer examined the fleshy nose parts of 45 different species, including more distant dino relatives such as mammals and turtles. “Evolution is such a quirky thing,†he said, that he didn’t expect to find a uniform nostril position in many different species. But he did, right at the tip of the nose in most cases. The similarity extends to humans.
When Witmer combined his findings in the living animals with his studies of the dinosaur fossils, he saw that the dinos also had nostrils far forward and low on the face.
“Nothing is ever universal in life,†he said. But in this case, “the exceptions certainly help to prove the rule.†Some monitor lizards, for example, have a fleshy nostril that is farther back. But these lizards have opted to sense their environment using a chemosensory organ instead of their sense of smell, which is very poor.
Nostril position may not be too important to humans because we rely mainly on our eyes for information about our surroundings. But smell is critical to animals, from dinosaurs to horses, that can’t see directly in front of them. Likewise, without fingers, dinosaurs’ sense of touch was focused around an incredibly sensitive mouth. The senses of smell, taste and touch were combined to explore for food and identify predators or prey. The position of the nostrils near the mouth--and out in front--made them far more useful to the dinosaurs.
The animal with the ultimate “rostral nostrils†is the elephant, which has developed a trunk to get those exploratory nostrils even farther out front.
Jack Hayes, the National Science Foundation’s director of ecological and evolutionary study, said that, as difficult as it is for paleontologists to reconstruct dinosaur skeletons from fossils, Witmer’s work was even more challenging because he had no starting materials. By using the living relatives, Witmer has “taken it another step,†Hayes said.
Witmer’s techniques may in fact be more important than his findings, said Oregon State University zoologist John Ruben. Although not involved in this study, Ruben is among the few researchers to use living relatives to learn about extinct species. Ruben said that Witmer’s work provides a rare example of a dinosaur reconstruction based on hard evidence rather than imagination.
Witmer’s past work has removed the cheeks from triceratops and the lips from T. rex, changes not always well received by dinosaur enthusiasts.
“My concern is to try to get it right,†Witmer said. With this work, “we’re allowing dinosaurs to be as they are, instead of how we shaped them.â€
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Nosing Forward
A new study suggests that dinosaurs’ nostrils were located farther down their nose than originally thought. Shown below is a Tyrannosaurus rex, with the lower illustration reflecting the more forward nostril position.
“Rostral†(up front) nostrils may have brought the nose closer to the tongue and mouth, improving the dinosaur’s ability to taste and touch.
