By Dan Satherley
Archaeopteryx – for a century-and-a-half considered the earliest of the earlybirds – might be getting the Pluto treatment.
Scientists are now suggesting it was just another feathered dinosaur and not a bird at all, recalling memories of when Pluto was stripped of its planetary status.
"There has been growing unease about the avian status of archaeopteryx as, one by one, its 'avian' attributes (feathers, wishbone, three-fingered hand) started showing up in non-avian dinosaurs," says Lawrence Wiltmer of Ohio University.
"Perhaps the time has come to finally accept that archaeopteryx was just another small, feathered, bird-like theropod fluttering around in the Jurassic."
The rethink comes after scientists in China discovered a new species, Xiaotingia zhengi, which shares many attributes with archaeopteryx, but belongs to a group of dinosaurs called deinonychosaurs. They found archaeopteryx belongs to the same group and is therefore a dinosaur, not a bird.
"This dinosaur is similar to archaeopteryx in general body plan, [with its] similarly shaped head, shoulder girdle, long and robust arms, similarly shaped pelvis, and feet with an initially developed highly extensible second toe," says Xing Xu of the Chinese Academy of Sciences, whose team made the discovery.
"[Both] came from the same family, the archaeopterygidae, and our analysis shows that archaeopteryx is slightly more primitive."
If their reinterpretation is accepted by the scientific community, it means that vertebrates have evolved the ability to fly on four separate occasions – birds, dinosaurs, reptiles and bats.
So if archaeopteryx isn't the oldest known bird, what is?
"Epidexipteryx and Epidentrosaurus, two species we described years ago, are probably the most primitive and oldest known birds," says Prof Xu.
It's widely accepted that birds evolved from dinosaurs, and the further back in time scientists look, the more similar they appear.
"Maybe archaeopteryx wasn't on the direct ancestral line to birds, but was part of an early experimentation in how to build a bird-like body," Paul Barrett, dinosaur researcher at the Natural History Museum in London, told the Guardian.
"It doesn't affect much of our big picture view of how birds came from dinosaurs, but some of the minutiae: the small changes that are important to the biology of the animals."
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