We've learned that dinosaur DNA from millions of years ago is too degraded to be deciphered, but scientists have been sequencing DNA from extinct animals, going further and further back as the art and science of genome sequencing advances. The oldest genome sequenced so far is from a leg bone of a horse ancestor that lived 700,000 years ago!
"We knew that sequencing ancient genomes as old as 70,000 to 80,000 years old was possible," said Ludovic Orlando, an evolutionary geneticist with the Natural History Museum of Denmark at the University of Copenhagen. "So we said, why not try even further back in time?"
The Pleistocene horse genome Orlando and colleagues pieced together helped them determine that the ancestor to the Equus lineage—the group that gave rise to modern horses, zebras, and donkeys—arose 4 to 4.5 million years ago, or about two million years earlier than previously thought. (Learn more about the evolution of horses.)
The bone used was found in the permafrost of Canada's Yukon Territory, which is a good environment for preserving DNA. Read more about the research at NatGeo News. Link
(Image credit: D.G. Froese via Nature)