“Monkeydactyl” – Strange New Jurassic Flying Reptile Reveals Oldest Opposable Thumbs
A new species of 160-million-year-old arboreal pterosaur dubbed “Monkeydactyl” has the oldest true opposite thumb – a new structure previously unknown in pterosaurs.
An international team of researchers from China, Brazil, the UK, Denmark and Japan have described a new Jurassic pterosaur Kunpengopterus antipollicatus, which was discovered in the Tiaojishan Formation of Liaoning, China.
It is a small-bodied darwinopteran pterosaur, with an estimated wingspan of 85 cm. More importantly, the specimen was preserved with an opposite pollex (“thumb”) on both hands.
The species name “antipollicatus” means “opposite thumb” in ancient Greek, in light of the opposite thumb of the new species. This is the first discovery of a pterosaur with an opposing thumb. It also represents the first record of a true opposing thumb in Earth’s history. The researchers published their finding today in the journal Current Biology.
A true opposite pollex occurs mostly in mammals (e.g. primates) and some tree frogs, but extremely rare among extant reptiles except chameleons. This finding adds to the list that darwinopteran pterosaurs such as K. antipollicatus also evolved an opposite thumb.
The research team scanned the K. antipollicatus fossil using micro-tomography (micro-CT), a technique that uses X-rays to image an object. By studying the morphology and musculature of its forelimbs, they suggest that K. antipollicatus may have used its hand for grasping, which is likely an adaptation to arboreal life.
To test the arboreal interpretation, the team analyzed K. antipollicatus and other pterosaurs using a set of anatomical characters related to arboreal adaptation. The results confirm that K. antipollicatus is an arboreal species, but not other pterosaurs in the same ecosystem. This suggests a niche distribution among these pterosaurs and provides the first quantitative evidence that at least some Darwinopteran pterosaurs were arboreal.
Fion Waisum Ma, co-author of the study and doctoral student at University of Birminghamsaid: “The fingers of ‘Monkeydactyl’ are tiny and partially sunk into the slab. Using the micro-scanner, we were able to see through the rocks, create digital models and tell how the opposite thumb articulates with the other finger bones.
“It’s an interesting discovery. It provides the first evidence of a true opposing thumb, and it comes from a pterosaur – which was not known to have an opposing thumb.
Xuanyu Zhou from the University of Geosciences of China who led the study commented: “Tiaojishan paleoforest is home to many organisms, including three genera of darwinopteran pterosaurs. Our results show that K. antipollicatus occupied a different niche from Darwinopterus and Wukongopterus, which likely minimized competition between these pterosaurs.
Rodrigo V. Pêgas of the Federal University of ABC, Sao Bernardo, Brazil, said: “Darwinoptera are a group of Jurassic pterosaurs from China and Europe, named after Darwin because of their anatomy. unique transition that revealed how evolution has affected anatomy. pterosaurs through time.
“In addition to this, a particular darwinopteran fossil has been preserved with two associated eggs, revealing clues to pterosaur reproduction. They have always been considered valuable fossils for these reasons and it is impressive that new species of Darwinoptera continue to surprise us!
Reference: “New Darwinopteran Pterosaur Reveals Arborealism and an Opposite Thumb” by Xuanyu Zhou, Rodrigo V. Pêgas, Waisum Ma, Gang Han, Xingsheng Jin, Maria EC Leal, Niels Bonde, Yoshitsugu Kobayashi, Stephan Lautenschlager, Xuefang Wei, Caizhi Shen and Shu’an Ji, April 12, 2021, Current biology.
The team consisted of researchers from: China University of Geosciences; Chinese Academy of Geological Sciences; Beipiao Pterosaur Museum of China; Federal University of ABC; University of Birmingham; Hainan Vocational University of Science and Technology; Hainan Tropical Ocean University; Zhejiang Natural History Museum; Aarhus University; University of Copenhagen; Fur Museum (Salling Museum); Hokkaido University; Geological Survey of China; Dalian Natural History Museum.