The Earliest Animal to have Opposable thumbs wasn't a Primate, It was this Pterosaur - Animalassic

The very first known creature to have evolved opposable thumbs wasn't a primate as many think, in fact, it wasn't even a mammal. The first animal known to us to possess opposable thumbs was a wukongopterid pterosaur from the Middle-Late Jurassic called Kunpengopterus antipollicatus.

Kunpengopterus Antipollicatus

Life reconstruction of Kunpengopterus antipollicatus by Chuang Zhao 

Kunpengopterus lived in north-eastern China approximately 160 million years ago during the Jurassic Period. It was a small-sized pterosaur with an estimated wingspan of 85 cm (33.5 inches).

The creature's rock-embedded fossil skeleton reveals that it could touch the insides of its thumbs to the insides of its other fingers, just like humans and, to a lesser extent, apes and most Old World monkeys and because of this, they have been nicknamed Monkeydactyl (meaning 'monkey fingered') by researchers.

Albino Kunpengopterus by Luxquine via Wikimedia commons

Researchers believe that Monkeydactyl would have used the pollices for arborealism (tree climbing), possibly in search of insects and other tree-dwelling prey, as its opposable thumbs allowed it to grasp tightly onto branches.

 

Kunpengopterus has an elongated head, 106.9 millimeters long. A low bony crest is present on the skull, just behind the eyes; preserved soft tissue shows it was elongated by cartilage and a yellow discoloration indicates that it was perhaps enlarged to the back by a skin flap. There is no sign of a crest on the snout or of a keel under the lower jaws. The back of the skull is rounded. Kunpengopterus has a long stiff tail. The fifth toe is also long and strongly curved.

Pterosaur egg by Maurilio Oliveira

The study of the egg specimen preserved alongside the female Kunpengopterus specimen nicknamed 'Mrs. T' revealed that the Kunpengopterus eggs had a parchment-like, soft shell, similar to the eggs of later pterosaurs and modern reptiles. These eggs typically absorb a significant amount of water during embryo development and are buried in the soil by the parent.

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References

• https://www.birmingham.ac.uk/news/2021/new-jurassic-flying-reptile-reveals-the-oldest-opposed-thumb
 
• https://www.cell.com/current-biology/fulltext/S0960-9822(21)00369-9?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0960982221003699%3Fshowall%3Dtrue
 
• https://www.newscientist.com/article/dn20011-did-pterosaurs-fly-out-of-their-eggs/