Fossilized bird had toes longer than its legs

When we die, the vast majority of us would appreciate it if we were remembered for some of our finer qualities, rather than those that may have made us seem “weird” compared to everyone around us. Unfortunately for an ancient bird whose foot was found preserved in amber, this is not the case.

A new study in the journal Current Biology details the discovery of a bird foot from 99 million years ago, preserved in amber. The ancient bird it belonged to appears to have a physical trait no other known bird has: toes longer than its legs. 

“I was very surprised when I saw the amber,” says first author Lida Xing of the China University of Geosciences. “It shows that ancient birds were way more diverse than we thought. They had evolved many different features to adapt to their environments.”

The researchers believe the bird may have used its extra-long toes to grab food out of tree trunks. They estimate the bird was smaller than a sparrow, and believe it spent most of its time in the trees. “Elongated toes are something you commonly see in arboreal animals because they need to be able to grip these branches and wrap their toes around them,” says co-author Jingmai O’Connor of the Chinese Academy of Sciences. “But this extreme difference in toe lengths, as far as we know, has never been seen before.”

Now named Elektorornis chenguangi, the specimen is believed to belong to a group of extinct birds called Enantiornithes. The bird’s foot was found in a piece of amber that measured over three centimeters in length. This amber was found in the Hukawng Valley of Myanmar, which during the Mesozoic era was full of trees that produced the resin that turns into amber when it becomes fossilized. Often, plants and small animals will get caught in the resin, leading to them being preserved in amber.

The only known animal that has such disproportionally long digits is the aye-aye, a lemur that uses its long middle fingers to hook insects and larvae out of tree trunks for food. Researchers believe the Elektorornis may have used its long toes for the same purpose. 

“This is the best guess we have,” says O’Connor. “There is no bird with a similar morphology that could be considered a modern analog for this fossil bird. A lot of ancient birds were probably doing completely different things than living birds. This fossil exposes a different ecological niche that these early birds were experimenting as they evolved.”

There is still more to be learned from this amber foot fossil, as the research team plans to extract the proteins and pigments from some feathers exposed on the surface of the amber. If possible, the resulting data could help them better determine the bird’s adaptation to its environment.

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By Connor Ertz, Earth.com Staff Writer

Image Credit: Zhongda Zhang / Current Biology