Baylor Researcher Uncovers Ancient Wildebeest-Like Animal's ‘Strange Adaptation’ Similar to Dinosaur

February 4, 2016

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WACO, Texas (Feb. 4, 2016) – While studying fossilized skulls of Rusingoryx atopocranion, an extinct wildebeest-like animal, unearthed on Kenya’s Rusinga Island, researchers discovered that the mammal had a very unusual, trumpet-like nasal dome similar to lambeosaurine hadrosaur dinosaurs that lived during the Cretaceous period.

“The thing that's really remarkable is that lambeosaurine hadrosaurs are the only other animals that we know of that have a similar feature,” said Daniel Peppe, Ph.D., associate professor of geosciences in Baylor's College of Arts and Sciences and co-director of the project. “This is a fantastic example of convergent evolution, which occurs when different animals end up evolving the same features independently. In this case, dinosaurs and bovids are obviously not closely related.”

This evolutionary convergence may be explained by similarities in the way Rusingoryx and hadrosaurs lived. According to the researchers, it appears that both the Rusingoryx and hadrosaurs evolved their nasal domes in a similar way and that it also developed in the same way as the animals aged from juveniles to adults.

“People have reconstructed that hadrosaurs were herbivores and likely lived in large herds in relatively open environments, and we think this was the case for the Rusingoryx,” Peppe said. “It seems likely that they both experienced the same evolutionary pressures to evolve a nasal crest that allowed vocalization. There are probably very few ways for animals to evolve these features and that if or when they do, it will happen in a similar way.”

Their research findings—published today in Current Biology— reveal that the little-known hoofed mammal’s unique nasal passage was most likely used for communication and probably sounded like a vuvuzela or horn, Peppe said.

Based on their anatomical investigations together with acoustical modeling, they think the trumpet-like nasal tube allowed Rusingoryx to deepen its normal vocal calls. In fact, their calculations suggest 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.

Additionally, these findings, as well as some of the groups other recently published work, potentially provide insight on human’s migration patterns during this time period.

“In the late Pleistocene about 50,000 to 100,000 years ago, when Rusingoryx was alive, Lake Victoria was either much smaller in size or had completely dried up and was replaced by a large grassland that probably expanded northward from the Serengeti,” Peppe said. “The removal of the geographic barrier allowed large mammals, like Rusingoryx to migrate across the region and also allowed a mixture of animals that now live far to the north of the equator to mix with animals that today live only south of the equator. Early modern humans were likely following the migrating animals, which may have allowed them to disperse across Africa and of Africa.”

The researchers will continue to explore the developmental shifts required to produce the animals’ bizarre morphology and attempt to understand what ultimately led the once-thriving Rusingoryx to disappear.

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