Filling a gap in history

The island continent of India drifted for 70 million years through the Tethys Ocean. It separated from Gondwanaland about 120 million years ago and collided with the Eurasian continent around 50 million years ago. 70 million years is enough time for large families of animals to evolve and die. So there must have been families which arose in the Indian landmass and migrated to the rest of the world later. The first such family has now been identified.

These are the Cambaytheres, a genus of fossil animals found at the bottom of an open-cast lignite mine outside of Surat in Gujarat. These 57 million years old fossils seem to be the origin from which all modern even-toed ungulates radiated out. These include horses and zebras, tapirs, as well as rhinoceros. The Cambaytheres were first described in an article published 6 years ago but I read about it only recently from a monograph published this year. The Cambay shale deposits have also yielded a very rich variety of other fossils from those times, and I’m sure we’ll be reading more about new finds from them.

The monograph has a very clear statement that although the genus is not the direct ancestor to any extant even-toed ungulate, it is the best possibility for the last common ancestor of all of them. Previous claims to the origins of this family are based on fragmentary fossil remains, or, sometimes, on conjectural remains. By the early years of the 21st century the possibility that the ancestors of horses originate in the Americas, Europe, and Africa had already begun to seem remote. A lot of attention then focused on new findings in China. Now, with a large collection of remains, from three species of this genus, much more can be said. Mysteries which remain are the routes through which the animals dispersed across the world, and then radiated into a large number of species in a few tens of thousands of years.