The fossilized remains of a strange and ancient bird whose central toes were longer than its thighs were found in an Amber mound of Myanmar.
The elongated tip resembles that of lemurs and lizards to climb trees and illustrates the unusual way of life of some of the first birds living alongside dinosaurs, researchers said.
"We have the leg of a small, 99-million-year-old bird, preserved in amber, which exhibits a unique foot morphology," said Jingmai O. Connor, vertebrate paleontologist and co-author of the Chinese Academy of Sciences study.
The foot was so distinctive that O'Connor and his team declared the bird, which was probably the size of a sparrow, a new species, Elektorornis chenguangi. The first part of the name translates as "amber bird". It is the first species of bird to be recognized of amber.
The bird's foot had four fingers, the third measuring 20% more than the lower leg of the bird and 41% longer than the second toe.
Scientists have compared the bird to the only other known species that has numbers of excessive length: the aye-aye, a type of lemur that uses its elongated fingers to catch larvae and insects in trunks. The researchers believe that Elektorornis could have used his toes for similar purposes.
The team believes that the bird probably spent most of its time in the trees rather than in the water or on the ground, developing its longer fingers to attach more easily to branches, as seen in lizards climbing trees.
In addition to its unusually long toes, it is thought that the bird has forked teeth and claws on the wings, as well as primitive feathers. He lived in a mangrove forest near the sea, alongside lizards, snakes and frogs.
The bird's leg, discovered in a piece of amber from the Hukawng Valley in Myanmar in 2014, was originally thought by traders as belonging to a lizard, but O'Connor's team quickly identified as an ancient bird's foot.
The study of the remains, published in the journal Current Biology, involved an amber scanner to produce a 3D reconstruction of the foot. The model was compared to 20 other extinct bird species and 62 existing species to fully establish its unique shape.
O'Connor said the fossil illustrates the "strange" lifestyle and anatomy of early birds, whose foot is just the latest of many animal remains found in Myanmar amber. Last year, another team of scientists discovered the remains of an ancient proto-spider encased in amber. The spider had a tail two times longer than its body, which could have been swept from one side to the other to detect predators.
The Chinese team now hopes to study the proteins and pigments in the feathers found on the surface of amber in the hope of better understanding how the bird has been adapted to its environment, for example by using its feathers to camouflage itself. .
Daniel Field, a vertebrate paleontologist from the University of Cambridge, who did not participate in the study, said: "The strange proportions of the foot of Elektorornis Stresses how much evolutionary history of birds has been unpredictable. He described the fossil as extremely well preserved. Without these fossils, "we would never have direct evidence of the deep, fanciful evolutionary history of birds," he said.