Khirtharia

Khirtharia is an extinct genus of raoellid artiodactyl that inhabited what is now northern India and Pakistan during the middle-upper Eocene (early Lutetian, 48 to 45 million years ago). There are three species of Khirtharia: K. dayi, K. inflata, and K. aurea. There is also a possible fourth species, K. major. Khirtharia is found primarily from Jammu and Kashmir and Northern Pakistan. More specifically, it is most commonly found in the Upper Subathu Group within Jammu and Kashmir. Khirtharia is notable for a well preserved skull of K. inflata, which allowed for obtaining an endocranial cast of the brain cavity.

The endocranial cast of K. inflata showed that the brain of Khirtharia was slightly smaller than that of the related Indohyus. The brain cavity had a volume of approximately 5.5 cubic centimeters, less than in contemporary artiodactyls, giving strong evidence that whales evolved from artiodactyls of relatively small brain sizes. It was also hypothesized that the small brain of Khirtharia could be an adaptation to a semi-aquatic life, supporting the position of Raoellidae as the sister group to whales (Cetacea).