Meet the ancient bird that had toes longer than its lower legs. Researchers have discovered a bird foot from 99 million years ago preserved in amber that had a hyper-elongated third toe. The study, published in the journal Current Biology on July 11, suggests that this bird might have used its toes to hook food out of tree trucks. This is the first time such a foot structure has been observed in birds, either extinct or living.
“I was very surprised when I saw the amber,” says first author Lida Xing at China University of Geosciences (Beijing). “It shows that ancient birds were way more diverse than we thought. They had evolved many different features to adapt to their environments.”
To study the Cretaceous period fossil, Xing and his colleagues scanned the amber with micro-CT and created a 3D reconstruction of the foot. They found that the bird’s third toe, measuring 9.8 millimeters, is 41 percent longer than its second toe and 20 percent longer than its tarsometatarsus, which is a bone in the lower legs of birds. The team compared the ratios with those of 20 other extinct birds from the same era and 62 living birds. No bird has a foot that resembles this one.