"This finding suggests that birds are likely to be descended from a kind of small-sized four-winged dinosaur about 160 million years ago," Xu said.It seems to be clear that a whole series of theropods were moving in the direction of flight. Which one got there first is still not known. We likely do not have enough information of the collateral ancestry of birds.
"It is a link between more typical theropods (dinosaurs which moved around with two rear limbs) and birds. It lived around a time period ... that we expected for birds' ancestor."
In a statement, the researchers said: "Long feathers cover the arms and tail, but also the feet, suggesting that a four-winged stage may have existed in the transition to birds."
The transition from dinosaurs to birds is still poorly understood because of the lack of well-preserved fossils, and many scientists say bird-like dinosaurs appear too late in the fossil record to be the true ancestors of birds.
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