Palaeontologist Christopher Gilbert discovered a 13-million-year-old fossil from northern India that appears to be the earliest known ancestor of the modern-day gibbon. The fossil belongs to a previously unknown genus and species called 'Kapi ramnagarensis'.

The discovery has been published in the article "New Middle Miocene ape (primates: Hylobatidae) from Ramnagar, India fills major gaps in the hominoid fossil record" in the journal Proceedings of the Royal Society B.

Gilbert and his team were searching for primate fossils in northern India when he noticed something small and shiny poking out of the dirt. He said, “We knew immediately it was a primate tooth, but it did not look like the tooth of any of the primates previously found in the area,"

In his observation, given the shape and size of the molar, the team’s initial guess was that the fossil might be from a gibbon ancestor. However, there were doubts leading to the fact that the fossil record of lesser apes is virtually non-existent.

The fossil was found in 2015. To verify the fact that tooth belongs to a new species of ape, Gilbert’s team compared it with corresponding teeth of living and extinct apes and monkeys.

Alejandra Ortiz, who was also the part of the research team, said, "What we found was quite compelling and undeniably pointed to the close affinities of the 13-million-year-old tooth with gibbons.”

Ortiz even called it a unique discovery. According to him, the findings pushes back the oldest known fossil record of gibbons by at least five million years. It provides a sight into the early stages of their evolutionary history.

The discovery is the first new fossil ape species that are found at the famous fossil site of Ramnagar, India, in nearly 100 years. It also provides important evidence about the migration period of the ancestors of today's gibbon from Africa to Asia.