Life reconstruction of Cambaytherium | Photo: Courtesy Dr. Kenneth Rose

Enter Uncle Cambaytherium. From India.

Although scientists still haven’t found the grandfather of all perissodactyls—“odd-toed” ungulates like horses—one international group has recently discovered and described a critical clue: their “uncle,” so to speak. Hundreds of Cambaytherium fossils, excavated from Indian lignite (brown coal) mines, provide evidence that the Cambaytherium and perissodactyls probably descended from the same common line. And that strongly suggests that equids could have evolved from a mammal that once roamed the great “island” of modern-day India before the land mass rammed into the continent of Asia 55 million years ago, said Kenneth Rose, PhD, emeritus professor at Johns Hopkins University, in Baltimore, Maryland.

Once entirely surrounded by ocean, the land that’s now India drifted slowly northward up from Madagascar over millions of years, Rose said. Completely isolated, the land mass harbored evolving mammals that had little or no contact with land-roaming species elsewhere in the world during most of that time. Cambaytherium was one of those, he said. Although it wasn’t a direct ancestor of horses (or rhinos or tapirs), it was what researchers call a “sister taxon”—meaning it was essentially a sibling species to the ancestor they wanted to find