Scientists Discover Oldest Known Opposed Thumbs on a Jurassic Era Dinosaur

These flying tree species were unearthed in China.
Fabienne Lang
K. antipollicatus and its phylogenetic positionCurrent Biology

A team of international scientists discovered a new, 160-million-year-old arboreal pterosaur species that has the oldest true opposed thumb. 

Dubbed the "Monkeydactyl" by the scientists, the Jurassic pterosaur species wasn't previously known to have opposed thumbs, so this discovery is particularly exciting as it sheds new light on how they might have adapted to living in trees. 

Officially known as Kunpengopterus antipollicatus (K. antipollicatus), this particular Monkeydactyl was found in the Tiaojishan Formation of Liaoning, in China.

To date, this is the oldest known creature to have opposed thumbs. 

The Monkeydactyl's history

The K. antipollicatus the team found was a small darwinopteran pterosaur with a 33.5 inch (85 cm) wingspan, and two opposed "pollex," or thumbs, on each hand. 

Typically, true opposed thumbs are predominantly found in mammals, like us humans, as well as some tree frogs, per the scientists' study, which was published in Current Biology on Monday, April 12. They can sometimes, in very rare cases, be found in extant reptiles, like geckos, as the team points out

The researchers were able to scan the fossil using micro-computed tomography (micro-CT). This enabled them to study in detail its morphology and musculature, and propose the species could have used its hands to grasp — something that likely evolved from its life living in trees. 

What the team discovered was that their results prove that this K. antipollicatus was an arboreal species, but also that other pterosaurs might not have been such tree-loving species. This suggests niche-partitioning among this species and the first piece of evidence that some evolved to live in trees. 

As Fion Waisum Ma, co-author of the study and Ph.D. researcher at the University of Birmingham, said "This is an interesting discovery. It provides the earliest evidence of a true opposed thumb, and it is from a pterosaur - which wasn’t known for having an opposed thumb."

It's thrilling to learn how species adapted and evolved over time, especially when finding out that more species had opposing thumbs, just like us.

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