How fossils are retelling our past

A dinosaur vertebra greets you as you enter G.V.R. Prasad's office in the Department of Geology at the University of Delhi. Two sides of the room are lined with fossils. Dinosaur eggshell fossils occupy a premium spot. And sharing space with dinosaur fossils are fossilised ammonites, trilobites, tiny fishes, starfishes and bones of an ichthyosaur, a marine organism that lived in the Jurassic period more than 150 million years ago.

The office is like a mini natural history museum — and that's not surprising, for the Professor of Geology is well known in India's palaeontology circles. In 2017, Prasad wrote in a scientific journal about a nearly complete skeleton of the ichthyosaur — a fish lizard — which had been discovered in the Kutch region of Gujarat. The discovery has improved scientists' understanding of the geographic distribution of animals and the palaeogeography of the time.

Earlier this year, Prasad and his colleagues reported an unusual egg fossil from what was once a dinosaur hatchery in Bagh in Madhya Pradesh. It was unusual, for it was an egg that had another egg nestling within it. This is rare for a dinosaur egg but is strikingly similar to pathological eggs known from modern-day birds. Birds lay a single egg at a time, but when conditions are not ideal, another egg or a layer of an egg is deposited over the first egg.