Ancient Wildebeest Ancestor Had Nose Of Duck-Billed Dinosaur
An extinct relative of the wildebeest boasted a trumpet-like nose similar to the strange hollow nasal crests of hadrosaur or duck-billed dinosaurs, according to a new study. Researchers say this discovery offers "a spectacular example" of convergent evolution between two very distantly-related animals across tens of millions of years.
"The nasal dome is a completely new structure for mammals- it doesn't look like anything you could see in an animal that's alive today," Haley O'Brien, a paleophysiology student at Ohio University, Athens, said in a news release. "The closest example would be hadrosaur dinosaurs with half-circle shaped crests that enclose the nasal passages themselves."
The ancient wildebeest-like animals, Rusingoryx atopocranion, lived about 65 thousand years ago, during the late Pleistocene era. Duck-billed dinosaurs, Lambeosaurine hadrosaurs, lived closer to 65 million years ago, during the late Cretaceous. Yet, both animals evolved the same strange nose – which developed the same way as the animals grew from juveniles to adults.
"When I first saw the complete skulls, I was blown away," vertebrate paleontologist David C. Evans, who was not part of the study, writes in an email to The Christian Science Monitor. "The resemblance between Rusingoryx and some hollow-crested dinosaurs in the form of their nasal structures is truly striking, and there are clear parallels in how they evolved and grew. Both groups elongated their noses to such a degree that they evolved highly domed skulls to house their nasal passages on top of their heads, above their eyes."
Based on an anatomical analysis and acoustical modeling, researchers believe the trumpet-like nasal tube may have allowed Rusingoryx to deepen its normal vocal calls and communicate with others across fairly large distances. In fact, the animals might have been able to call at levels very close to infrasound, such that other animals may not have been able to hear individuals in the herd calling back and forth to each other.
"Vocalizations can alert predators, and moving their calls into a new frequency could have made communication safer," O'Brien added. "On top of this, we know that [both] Rusingoryx and hadrosaurs were consummate herbivores, each having their own highly specialized teeth. Their respective, remarkable dental specializations may have initiated changes in the lower jaw and cheek bones that ultimately led to the type of modification we see in the derived, crest-bearing forms."
In future studies, researchers hope to learn what led to the once-thriving Rusingoryx's mass exit.
Their study was recently published in the journal Current Biology.
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