The oldest opposable thumb in the world belongs to a new species of flying reptile, an arboreal pterosaur that lived in China 160 million years ago: small in size and with a wingspan of 85 centimeters, it was called 'Kunpengopterus antipollicatus' precisely in reference to the particular anatomical structure of the front legs (never found before in pterosaurs) which he probably used to cling to trees.
The discovery is published in the journal Current Biology by a group of Chinese, Brazilian, British, Danish and Japanese researchers, led by paleontologist Xuanyu Zhou of the Chinese University of Geosciences in Beijing.
The pterosaur fossil was found in the Tiaojishan formation, in the Chinese province of Liaoning, and was subjected to a computerized micro-tomography: this X-ray technique made it possible to recognize the fingers, "small and partially embedded in the rock", in in order to recreate “digital models that show how the opposable thumb articulates with other bones,” explains Fion Waisum Ma, a researcher at the University of Birmingham and co-author of the study.
"This is an interesting discovery: it gives us the earliest evidence of a true opposable thumb and it comes from a pterosaur, which until now was not thought to have one."
This anatomical structure is mostly present in mammals (such as primates) and in some tree frogs, while it is extremely rare among living reptiles, with the exception of the chameleon.
