The evolutionary family tree of whales now has Indian roots. Just completed analysis of a 2005 discovery of a 48 million-year-old fossil of Indohyus, a fox-sized mammal that looked like a deer, indicates that it could be the closest fossil relative of whales.
The fossil was discovered at Kalakot in Kashmir.
Scientists now say whales evolved from this particular even-toed plant-eating mammal that permanently shifted to the sea and eventually became the largest marine carnivore.
It is already established that whales descended from land animals, but the identity of that animal was a mystery till date. With researcher J G M Thewissen from the US, Sunil Bajpai of IIT-Roorkee and B N Tiwari of the Wadia Institute of Himalayan Geology, Dehradun, reported the findings this week in the science journal Nature.
“Our study found key similarities in the skull and ear regions, between whales and the Kalakot animal which spent much time in water,'' said Bajpai. “We also explored how this ancestor of whales lived, and came up with surprising results.”
They found that the bones of Indohyus had a thick outer layer, a characteristic often seen in slow aquatic waders like the hippopotamus. Chemical composition of its teeth also revealed oxygen isotope ratios similar to aquatic animals. Previously, it was assumed that whales descended from carnivores, but this study has indicated that they were probably herbivores. Their dietary shift to hunting animals evolved after their habitat shifted to water.