A study from the University of Alberta has revealed that some dinosaurs with feathers may have attracted mates based on their tail plumage. The research, which was led by University of Alberta paleontology researcher Scott Persons, specifically looked at fossils of dinosaur tail bones to reach a conclusion. The study specifcally focused on four species of dinosaurs that spanned 45 million years of evolution.
In a paper published in the journal Acta Palaeontologica Polonica on Friday, Persons and his research team fused dinosaur vertebrae from the head to the tail in order to understand the differences in the vertebrae across the species. According to Persons, the last few vertebrae of the oviraptors, a group of dinosaurs, were fused to create a unique blade-like structure with ridges called a pygostyle.
“The structure is called a pygostyle” says Persons. “Among modern animals only birds have them.”
Previous fossil research has revealed that an early oviraptor called Similicaudiptery had feathers that grew off of the final fused vertebrae. However, Similicaudiptery was not a flying dinosaur. Persons hypothesizes its feathers were more for tail waving than any other function.
“Think of it as a trip to Las Vegas, because there would be tail-feather fans on showgirls for you,” said Persons, who studied fossils found in Mongolia. “Between the crested head and feathered-tail shaking, oviraptors had a propensity for visual exhibitionism.”
Following Similicaudiptery, no evidence has been found that other oviraptors had feather. Despite this, Persons believes there is still ample proof to suggest Similicaudiptery had feathers on its tail. Although there is no evidence of feathers in later oviraptors, because their tail vertebrae are so similar to Similicaudiptery, Persons believes they had also had feathered tails.
Similarity to Similicaudiptery isn’t the only thing that has led Persons to believe oviraptors waved feathered tails. In fact, he has found significant evidence for the claim in the bone and muscle structure of the groups’ tails.
By studying fossils, the researchers revealed that the oviraptor’s tail was very flexible as a result of many short vertebrae at the base of the tail. This is a feature seen in the tails of many modern day reptiles and birds. In addition, large muscles that reached down the tail with many insertion points on the vertebrae are thought to have allowed the oviraptor to robustly shake its tail back and forth and up and down.
Their feathered tails may not have been the only thing oviraptors used to gain mates. Persons has also found evidence that the dinosaur group used bone crests on the top of their heads in order to attract significant others. “Between the crested head and feathered-tail shaking, oviraptors had a propensity for visual exhibitionism,” he said.
The proposed feathered tail of the oviraptor is not the only thing that set this dinosaur group apart from others. Oviraptors lived in the Cretaceour period just before the extinction of the dinosaurs. Being one of the last surviving dinosaur groups, oviraptors had diverged majorly from the original meat eating dinosaurs. Oviraptors ate only plants and lived throughout China, Mongolia, and Alberta.
Persons believes this divergence allowed oviraptors to use their feathered tails more like modern day birds.
“By this time a variety of dinosaurs used feathers for flight and insulation from the cold,” he said. “This shows that by the Late Cretaceous dinosaurs were doing everything with feathers that modern birds do now.”