For the first time, Indian palaeontologists have unearthed hominoid ape fossils from localities in Gujarat.
The researchers consider the finding to be important because it is the first proof of the presence of apes outside the Himalayas. “Such localities are globally rare and every new locality brings a lot of excitement,” says Ansuya Bhandari, a palaeontologist at the Birbal Sahni Institute of Palaeosciences, Lucknow, who found the fossil and led the study.
“This discovery is very important [as it indicates] similar ecological conditions 11 million years ago in Kutch and in Himalayan region,” V.P. Mishra, former deputy director general of the Geological Society of India, told The Wire. He wasn’t involved in the study.
The researchers have been able to date the fossil to 10.8 million years ago (mya) – from the Miocene epoch.
This geological period lasted between 23 and 5 mya. It has thrown up many hominoid remains that have contributed to our understanding of the evolution of humans since the first such fossil was found in the Potwar plateau in Pakistan, 1879. In the last 140 years, hominoid fossils from the Miocene age “have been found along the Siwalik foothills of the Himalayas in Pakistan, India and Nepal only,” according to Bhandari.
Until now.
That means this discovery is a potential game-changer. “We now know that Sivapithecus” – the ancestor of the modern apes, it resembled an orangutan and lived in the Miocene between 12.5 and 8.5 mya – “had fairly extensive range, from Kutch in the south and west to Nepal in the north and east,” says David R. Begun, an anthropologist at the University of Toronto, Canada. “It must have been a successful species to be found in so many places around 10 million years ago.”
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In other words, palaeontologists might be able to find more such fossils from the region. If they do, they will be able to build a clearer picture of how these ancestors of the great apes could have migrated to the south of the Himalayas.
“This discovery from Kutch would greatly help in understanding the connection of Himalaya fauna with that of the Indian peninsula,” according to Bhandari.
In India, most hominoid fossils have been found in the Hari Talyanagar and Ramnagar basin in Jammu and Kashmir. The Ramnagar fossils have been dated to around 12.7 mya and the Hari Talyanagar fossils, between 9.2 and 8.6 mya.
Miocene hominoids are divided into two groups: the larger bodied Indopithecus and the smaller Sivapithecus. The sole species in the former group, Indopithecus giganteus, was reported from Hari Talyanagar in 1969. Three species of the Sivapithecus – S. indicus, S. parvada and S. sivalensis – have been found across the Pakistani and Indian Siwalik mountains.
“We didn’t expect to find hominoid here (Kutch),” says Sunil Bajpai, who heads the Department of Earth Sciences at IIT Roorkee and was part of the study.
But Bhandari and Bajpai were hopeful. In the winter of 2011, they were in Kutch looking for fossils. The area has thrown up many fossils in the past, including those of whales, crocodiles, sawfish, turtles and other marine creatures. A few years prior, they had found remains of giraffes, rhinos, and animals resembling today’s elephants and boars as well. These findings had allowed them to hypothesise that these creatures had migrated from Africa and Europe at the time of the Gondwana supercontinent.
To piece together the geological timeline of these events, the team began looking for the fossil remains of rodents, which are among the first animals to colonise a region.
Towards the end of that field trip, a rocky clearing with some patterns on it caught Bhandari’s attention. Some digging and cleaning around the pattern revealed a jaw – the first indication that hominoids travelled south of the Himalaya.
The upper right jaw of an adult hominoid. Credit: Bhandari et al
The researchers figured that the fossil was the right upper jaw of an adult hominoid. It includes parts of the thickened ridge that contains teeth sockets that connect to the cheekbone and ridge of the mouth.
The canine and molar teeth were also identifiable. A CT scan reveals that although the enamel caps were damaged, it was possible to estimate the teeth’s dimensions.
The proportions of the canine and premolars were found to be more similar to Sivapithecus than Indopithecus. Specifically, the first and second molars were round with poorly developed cresting, as in other Sivapithecus and Miocene apes.
Although this feature was clinching, the team wanted to make sure they were on the right track anyway. So they took the help of a horse.
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In 2011, the team had found remains of a Hipparion for the first time. The Hipparion is the ancestor of the modern-day horse and originated in North America. According to Bhandari, its presence is a “biological marker” because it spread across Gondwanaland between 2 and 22 mya. The jaw and the Hipparion fossils were both dated to around 11 mya. Indopithecus had first shown up 9 mya. Thus, the jaw likely belonged to a Sivapithecus ape.
The Miocene epoch, between 15 and 7 mya, had a warm, humid climate with evergreen and deciduous forests covering large parts of the Indian subcontinent’s north. These forests eventually gave way to savannahs with open, arid habitats. The species that inhabited these forests either moved southward or perished.
“I just want to show that there was connectivity of Himalayan fauna with the Kutch region,” says Bhandari, most likely due to similar liveable conditions. “But we need more fossils from the region to piece the puzzle together.”
The study was published in the journal PLoS ONE on November 14, 2018.
Vrushal Pendharkar is a freelance science writer.