Canadian researchers have found the first feathered dinosaur specimens in the Western Hemisphere, and suggested that the ornithomimids, as they are scientifically known, should have had feathers and wings.
The study, published Friday in the prestigious journal Science, was led by paleontologists Darla Zelenitsky from the University of Calgary and Francois Therrien from the Royal Tyrrell Museum of Palaeontology.
Zelenitsky said that despite the many ornithomimid skeletons known, these specimens are also the first to reveal that ornithomimids were covered in feathers, like several other groups of theropod dinosaurs.
The researchers found evidence of feathers preserved with a juvenile and two adult skeletons of Ornithomimus, a dinosaur that belongs to the group known as ornithomimids, suggesting that all ornithomimid dinosaurs would have had feathers.
Besides, the specimens, recovered from 75 million-year-old rocks in the badlands of the Canadian province of Alberta, reveal an interesting pattern of change in feathery plumage during the life of Ornithomimus.
"This dinosaur was covered in down-like feathers throughout life, but only older individuals developed larger feathers on the arms, forming wing-like structures," said Zelenitsky. "This pattern differs from that seen in birds, where the wings generally develop very young, soon after hatching."
This discovery of early wings in dinosaurs being too big to fly indicated the initial use of these structures was not for flight, according to the researchers.
"The fact that wing-like forelimbs developed in more mature individuals suggests they were used only later in life, perhaps associated with reproductive behaviors like display or egg brooding," said Therrien.
Previously, feathered dinosaur skeletons had been recovered almost exclusively from fine-grained rocks in China and Germany. The discovery of these ornithomimids in sandstone reveals great new potential for the recovery of feathered dinosaurs worldwide, according to the researchers.
