The subterranean world is called the chthonic, from the Ancient Greek ‘khthoniós’, meaning “in, under or beneath the earth.” Geologists, palaeontologists, archaeologists, plant and tree researchers and mythologists have all been fascinated with this hidden place and its secret riches.Of them, a palaeontologist’s life combines a love of nature, a desire to visit unknown places, finding fossils and interpreting their features to glean meaningful information about their lives, Ashok Sahni, one of India’s foremost exponents of this field of study, said.Sahni’s grandfather, born in 1862, was one of the first graduates of Punjab University, where he studied chemistry and physics; he was later a professor of chemistry in Lahore. His children all became scientists, doctors or technologists. One of them, Birbal Sahni, became a fellow of the Royal Society.Conversations around the Sahnis’ dinner table focused on evolution, fossils and mammals. They would travel to the hills of Kashmir, Shimla and Nainital, to collect stones and look for fossils.Ashok Sahni was born in Calcutta and obtained his masters’ degree in geology from Lucknow University. He left for Minnesota when he was 22 for a PhD in palaeontology. He wasn’t particularly interested in fossils at the time but this changed when he enrolled with a project in Montana that required participants to dig for dinosaur fossils. Montana is famed for its fossil riches, especially at a rock formation called Hell’s Creek in the state’s northeast.He returned to India with a PhD in 1968, enrolled to teach at Lucknow University and began in earnest to look for dinosaurs in India.“From 1959 to 2019, I have been doing this work,” Sahni, now 79, said.His first stop was Jabalpur, where locals had recently reported finding some fossils. The oldest records of dinosaur fossils in India dates to 1828, by a captain of the East India Company who packed his discoveries off to a museum in the UK. Dinosaurs would be defined as a new reptilian group only 14 years later.Rocks have a way of thrusting surprises on researchers, so perseverance and luck – together with a dedicated team – play a big part in discovering fossils. Many students have been a part of this team, and some of them have gone on to make discoveries of their own, of a primitive assemblage of mammals and associated vertebrates in Kalakot, Kashmir, of the remains of 50-million-year-old fish in Rajasthan and of “the earliest whales anywhere in the world” in Kutch.By 1973, the team was learning so much that Sahni said they “started publishing like mad”.One of Sahni and co.’s more famous discoveries is of a group of mammals alongside dinosaurs fossils, first published in 1988. They also discovered dinosaur nests and eggs in Jabalpur in 1982 and then in other places across central India. The Jabalpur site turned out to be one of the largest dinosaur nesting sites in the world. In 2005, Sahni handed one of his students some specimens of amber and asked him to study them. Under a microscope, the study found that the amber contained insect fossils; one of them was 54 million years old.Such fossils “give you an idea of how insects evolved in early tropical evergreen forests,” Sahni said.Also read: Found and Lost: An Indian Fossil Hunter’s Chase for Dinosaur RelicsIndeed, scientists have since established that the Indian subcontinent was once home to Earth’s first whales. The first whale had descended from a land-based sheep-like animal and had four limbs, but its descendants lost them to become completely limbless and more and more like the colossal marine creatures we know today. Likewise, the ancient sea floor of the Kutch has been a boon for palaeontologists.Before India collided with Asia and gave birth to the Himalayan mountains, there was a vast waterbody along the line of collision called the Tethys Sea. “One arm of the sea must have been in the Kutch area,” Sunil Bajpai, a palaeontologist at IIT Roorkee, said.When Bajpai first started out, he decided to work on whale fossils because they “were poorly described then”. As part of his doctoral studies, he visited Kutch in 1986. The first few days didn’t yield anything, plus he was new and the weather was hot and dry, so he was miserable.Then he found an ancient whale’s fossilised brain case – the first in India. “The surface morphology of the original brain is preserved on the surface of the cast,” he said. “That gives you an idea about the size and gross structure of the brain.” As the days passed, Bajpai began to make more discoveries. He finally left for Chandigarh, where he began to look for pictures of similar fossils found around the work for him to compare and describe.Subsequent visits yielded a wealth of material, such as skulls, jaws and “whole skeletons actually”.Since the 1990s, Bajpai has collaborated with the noted Dutch-American palaeontologist Johannes “Hans” Thewissen, including on studies of the Kutch area fossils. “How the early mammals evolved, how they dispersed – these questions interest me,” he said.Bajpai’s collection today includes sea whales, various cat-fishes, crocodiles, some marine turtles, herbivorous sea mammals and sea cows. Indeed, he also has “well-preserved fossils of sea cows found at the same levels where you find fossil whales.”But for the wealth of information we have to understand how different animals evolved around our planet, it’s not as if the plants haven’t been up to much. In fact, and given humankind’s increasingly misguided conviction that simply installing more plants could stave off the worst effects of climate change, the secret lives of trees suggest Earth’s flora evolved in magical ways of its own.For example, consider the ‘wood-wide web’, a vast subterranean network of roots, fungi and bacteria that connect tress old and young to each other.Fungi live on plant roots and, using filaments called hyphae, they branch out through the soil towards the roots of other plants, where they form bonds at the cellular level. The fungi and roots together form the mycorrhiza: a union in which the fungus supplies nitrogen and phosphorous extracted from the soil and the plant supplies carbon-based sugars produced by photosynthesis.This symbiotic relationship becomes the basis for an underground community that works by cooperation, redistribution of biochemical resources and warning of potential insect attacks.Also read: Why Simply Planting More Trees Won’t Help Us Deal With Climate ChangeTamir Klein, a researcher at the department of plant and environmental sciences, Weizmann Institute of Science, Israel, explained that trees compete with each other but also exchange materials. “In general, they interact in very complex ways.”When he a postdoc, Klein was part of a team that discovered trees also exchanged carbon through the mycorrhizal network. The team’s leader, Christian Koerner, a professor at the University of Basel in Switzerland, refused to trust Klein’s results at first. “Later, I traced the carbon from the stem to the roots of specific trees, and proved that matter moves in between trees,” Klein said.“I’m just curious and want to understand the world better. I’m intrigued by what I cannot see.”G.B.S.N.P. Varma is a freelance journalist.
