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Fossils Indicate Dinosaurs May Have Shaken Tail Feathers In Elaborate Mating Display

January 7, 2013
Image Caption: Artist's conception of the feathered dinosaur Similicaudipteryx using its tail feathers in a mating display. Credit: Sydney Mohr

Alan McStravick for redOrbit.com – Your Universe Online

This week University of Alberta researchers examining the fossilized remains of dinosaur tail bones made what appears to be a startling discovery. Our modern day birds like the turkey and the peacock, which often use their dazzling plumage to attract a mate, may be channeling their long-departed ancestors: the feathered dinosaurs.

This discovery was not made in a single find, however. Scott Persons, a paleontologist at the University of Alberta, made the connection after examining a chain of fossil evidence that showed a peculiar fusing together of vertebrae at the tip of the tail on four different species of dinosaur. Some of these species were separated by 45 million years of evolution.

According to Persons, it was the final vertebrae in the tails of a group of dinosaurs known as oviraptors that was fused together. This fusing formed a ridged, blade-like structure. “The structure is called pygostyle,” explained Persons. “Among modern animals, only birds have them.”

According to the researchers, one of the early oviraptors was the Similicaudipteryx, which had a radiating feather formation from the fused bones at the tip of its tail. While Similicaudipteryx was not known to be a flying dinosaur, Persons contends that the evolution of tail feathers came about as a means of waving its feathered tail fans.

The oviraptors were two-legged dinosaurs that were already a far cry from their earlier meat-eating cousins. Their diet consisted primarily of plants, and they were known to have roamed parts of what are now modern-day China, Mongolia and Alberta during the final age of the dinosaur, the Cretaceous period.

Despite no direct fossil evidence of feathers on the oviraptors that came after Similicaudipteryx, Persons believes that due to both the bone and muscle structure of the tails of the descendants of Similicaudipteryxy, there is still strong evidence that they had a feathered tail. He also suspects that the late-coming oviraptors´ tails served the same purpose as it had in their progenitors.

The team´s findings show that the individual vertebrae at the base of the oviraptor´s tail tended to be short and numerous, indicated flexibility and ease of movement. Basing his hypothesis on the dissections of both modern reptile and bird tails, Persons claims that the reconstructed dinosaur tail muscles clearly reveal that oviraptors could really shake their tail feathers.

The study, published in this week´s edition of the international journal Acta Palaeontologica Polonica, shows how Persons, lead author of the paper and a PhD candidate in paleontology at the University of Alberta, came to show that it was a grouping of large muscles extending down the tail to a broad conflagration of connection points on the vertebrae that allowed the oviraptors to propel their tail feathers vigorously from side to side as well as in an up and down motion.

“By this time, a variety of dinosaurs used feathers for flight and insulation from the cold,” said Persons. “This shows that by the late Cretaceous, dinosaurs were doing everything with feathers that modern birds do now,” said Persons.

Persons goes on to further describe the Cretaceous oviraptors, pointing out that they also had a prominent bone crest on their head. He believes this crest, like the vigorously shaking tail feathers, were used to great effect, in mating displays.

In addition to feathered-tail waving, oviraptors also had prominent bone crests on their head, which Persons says the dinosaurs also may have used in mating displays. “Between the crested head and feathered-tail shaking, oviraptors had a propensity for visual exhibitionism,” he stated.


Source: Alan McStravick for redOrbit.com - Your Universe Online