Two detailed fossils are introducing researchers to a new bird, one that lived around 130 million years ago and is being called the oldest known example of the group containing modern birds. The new bird has been named Archaeornithura meemannae. Feathers cover almost the entirety of its body, including its head, neck, shoulders, and wings, though the bird's legs and feet are bare. The bare legs suggest that Archaeornithura — or its ancestors — came from a semi-aquatic environment where it was used to wading. The finding is being published today in Nature Communications.
"It gives us crucial new information on their origins and early evolution."
"The new fossil bird Archaeornithura is an important find," Matthew Lamanna, an assistant curator at the Carnegie Museum of Natural History who was not involved in the study, writes in an email to The Verge. If it’s been dated correctly, Lamanna says, Archaeornithura pushes back the fossil record of birds’ most recent ancestors by 5 million to 6 million years.
The group behind the study, which was led by a researcher from the Chinese Academy of Sciences, located the two fossils in the Sichakou basin in Hebei, a province in northeast China. This is part of the second-oldest formation in the world that's been found to carry bird fossils, but only a small number of distinct samples have actually been found there.
Discoveries like Archaeornithura help researchers to define the transition between dinosaurs, primitive ancestors of birds, and the birds that we see today. Some "extraordinary" fossils have made the transition between dinosaurs and primitive birds "fairly well understood," Lamanna says, "but the transition from these primitive birds to the species we see flying around us today is much less known."
As the oldest known member of the modern bird group, Archaeornithura is a key find toward allowing researchers to figure that out. "It gives us crucial new information on their origins and early evolution," Lamanna says.
There are likely older birds waiting to be found
Archaeornithura stands out for having advanced features that are similar to modern birds while still having primitive traits. Min Wang, the study's lead author, says that Archaeornithura can be considered to "have many morphological features of modern birds," at least when you compare it to other birds living around 130 million years ago. But it still has some major differences, he says, such as the claws on its hands.
Wang also suspects that future excavations will push the timeline for this modern bird group, Ornithuromorpha, back even further. Between the evolutionary timeline researchers are already seeing and the geological structure of the formation where Archaeornithura was found, there's an indication "that there are specimens older than the new specimen," Wang tells The Verge in an email. "Therefore, it is likely we can find specimen of Ornithuromorpha from older deposits."