June 3 (UPI) -- Feathers arrived at least 100 million years before birds, according to a new survey.
Using new data in the fields of palaeontology and molecular developmental biology, scientists were able to clarify the evolutionary relationships among dinosaurs, birds and pterosaurs, a group of bird-like flying reptiles.
Earlier this year, researchers discovered feathers in pterosaur fossils, the first evidence that feathers emerged much earlier than birds on the evolutionary timeline.
"The oldest bird is still Archaeopteryx first found in the Late Jurassic of southern Germany in 1861, although some species from China are a little older," Mike Benton, professor of vertebrate palaeontology at the University of Bristol, said in a news release. "Those fossils all show a diversity of feathers -- down feathers over the body and long, vaned feathers on the wings. But, since 1994, palaeontologists have been contending with the perturbing discovery, based on hundreds of amazing specimens from China, that many dinosaurs also had feathers."
The first dinosaur fossils to reveal the presence of feathers were around the same age as the earliest evidence of feathers among birds.
"This was not so hard to believe," said paleontologist Baoyu Jiang from the University of Nanjing. "So the origin of feathers was pushed back at least to the origin of those bird-like dinosaurs, maybe 200 million years ago."
But when scientists found feather-like whiskers all over the body of a dinosaur discovered in Russia, they realized the feather's evolutionary history needed to be rewritten.
"What surprised people was that this was a dinosaur that was as far from birds in the evolutionary tree as could be imagined," said Maria McNamara, researcher at the University College Cork. "Perhaps feathers were present in the very first dinosaurs."
Findings in the field of molecular biology showed the same genetic pathways controlled reptile scales, bird feathers and mammal hairs -- more evidence that feathers could have emerged early.
According to the new survey, published this week in the journal Trends in Ecology and Evolution, real clarity arrived when scientists found a pair of ancient pterosaurs in China.
"We saw that many of their whiskers were branched," Benton said. "We expected single strands -- monofilaments -- but what we saw were tufts and down feathers. Pterosaurs had feathers."
The succession of revelations recently regarding the origin of feathers suggest they emerged during the Early Triassic, in the wake of a devastating mass extinction event. Life was quickly evolving as new species filled the many ecological voids.
"Paleontologists had already noted that the new reptiles walked upright instead of sprawling, that their bone structure suggested fast growth and maybe even warm-bloodedness, and the mammal ancestors probably had hair by then," Benton said. "So, the dinosaurs, pterosaurs and their ancestors had feathers too. Feathers then probably arose to aid this speeding up of physiology and ecology, purely for insulation. The other functions of feathers, for display and of course for flight, came much later."