It was just another fossil-hunting expedition in 2012 for A. R. Sankhyan at the Haritalyangar fossil beds in Himachal Pradesh, India. While searching for micro-fossils near the small village of Barada, he was painstakingly sieving through mud and soil, when he discovered the fossils of two small molar teeth. 

Although he had an inkling about the importance of his discovery, it would be several years before the fossils would yield their secrets. Five years of careful study have now led to the identification of these nine-million-year old teeth as those belonging to Krishnapithecus krishnaii, a representative species of a group of extinct ape ancestors called Pliopithecoids. These findings were published as a paper in the Journal of Human Evolution and as a brief scientific correspondence in Current Science

“Studying these new findings was a mind-boggling exercise. Cleaning the material and getting good-quality images and measurements was a very taxing process. Also, identification and comparisons were a challenging task since the only other known fossil for Krishnapithecus was a worn upper molar also recovered from Haritalyangar,” says Sankhyan, who is a faculty member at the Anthropological Survey of India and the Palaeo Research Society, Ghumarwin. ​“But my co-authors – Jay Kelley, Tim Harrison and I persisted, and we were able to work with published images and measurements to identify the fossil teeth I discovered,” he adds.

The Haritalyangar fossil beds, where the teeth have been found is known mainly for yielding a rich diversity of small-mammal fossils and fossils of the ape-like hominids Sivapithecus and Gigantopithecus(also known as Indopithecus). The latest findings from this area, however, belong to the now-extinct superfamily of Old-World primates, the Pliopithecoids. The Pliopithecoids were known to be widely found in Eurasia during the Miocene (roughly 18 to 7 million years ago), but their fossils have almost never been found in South Asia. The discovery of these fossils presents for the first time, clear proof of the presence of Pliopithecoids in South Asia.

The two fossil teeth from Haritalyangar are lower molar germs — permanent teeth that are still forming in the lower jaw, with fully formed crowns but undeveloped roots — a sign that the teeth likely belonged to infants. The fossilised teeth discovered by Sankhyan come from two different individuals, and bear unmistakeable Pliopithecoid features. 

The fossils also reveal that K. krishnaii was perhaps the largest of all known Pliopithecoids, with adults weighing in at around 14 kilogrammes. Sankhyan hypothesises that K. krishnaii probably looks like the modern day Siamang, a South-east Asian gibbon, though slightly larger in size. The fossil molars also indicate that K. krishnaii existed on a diet of fruits and soft leaves in what was once the Siwalik forests of the Miocene which they shared with other hominids such as Sivapithecus.

Rajeev Patnaik from the Centre for Advanced Study in Geology at Panjab University, who was unconnected to this study says, ​“the findings from Haritalyangar come from a well dated site, suggesting that Pliopithecines survived till the late Miocene in South Asia, perhaps due to the existence of forests in this part of the world during that period.” Patnaik is excited about the discovery as it adds to the diversity of primate findings from Haritalyangar. Supportive of more fieldwork at this site he says, ​“there is still a lot of scope for fossil primate discovery in the Siwaliks of India.