Khirtharia
Khirtharia is an extinct genus of raoellid artiodactyl that inhabited what is now northern India and Pakistan during the middle-upper Eocene. 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 of northern India. 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.
As a raoellid, Khirtharia would be a relatively small, omnivorous, semiaquatic mammal. Khirtharia had the highest level of carnivory out of all raoellids. Khirtharia as a whole is relatively normal sized for a raoellid, but it had the largest variation in size within its genus. It had hooves and a large tail. Khirtharia'' was a good swimmer, and likely used this advantage to escape from predators.
Discovery
The first remains of Khirtharia were unearthed in 1940 by Ernest Sheppard Pinfold while working for the Attock Oil Company, who stored the remains in the British Museum. He found the remains in the Khirthar fold belt, which is a foldbelt found in Pakistan created by the formation of the Himalayan mountains. Khirtharia was then named by Guy Ellcock Pilgrim in 1940 after he was invited to the museum by the head of geology and the fossils of Khirtharia were given to him by Pinfold, including remains found by other geologists in the Attock district of Punjab At the time, all of the remains of Khirtharia were extremely fragmentary. Guy Pilgrim named the first and type species K. dayi. It was named from a fragmentary mandible and maxilla with some of their respective premolars and molars. In 1972, the new species Bunodentus inflatus was discovered by A. Ranga Rao. In 1980, Robert M. West suggested that Bunodentus, at the time known only from an isolated molar and fragmentary mandible, was synonymous with Khirtharia dayi, although this change was only officially enacted in 1985 by Kumar and Sahni who believed B. inflatus was different enough from K. dayi to warrant being placed under a different species. In 1978, Indohyus major was described by Hans Thewissen and colleagues from a single molar in Pakistan. It was named I. major due to the size of the tooth, being approximately twice the size of other raoellid teeth. In 2012, Orliac and Ducrocq found that the tooth of I. major was more similar to Khirtharia, and thus assigned the species to Khirtharia as K. major. In 2001, K. aurea was named by Thewissen and colleagues from material in northern Pakistan.Classification
The placement of Khirtharia has varied throughout the history of the taxon. Generally, it has been assigned to basal groups of artiodactyls, although it is currently a member of Raoellidae. When Khirtharia was first named by Pilgrim, it was assigned to Helohyidae. However, in 1958, Dehm and Oettingen-Spielberg moved Khirtharia, along with Haqueina, to Dichobunidae which was corroborated by Sahni and Khare in 1972 and Gingerich in 1977. Later in 1977, when Coombs and Coombs reevaluated Helohyidae, they determined that the remains of Khirtharia were not diagnostic of any particular family of artiodactyls, and therefore left Khirtharia as an artiodactyl of uncertain position. In 1980, Robert West reaffirmed KhirthariaDescription
Raoellids were a group of mammals closely related to cetaceans. They were generally small and semiaquatic. In life, they would appear similar to the modern day chevrotain, but with a more dog-like snout and large, robust, tail. All members of Raoellidae had denser bones than average for an artiodactyl, hinting at their semiaquatic nature. Denser bones are characteristic of aquatic and semiaquatic animals, such as hippopotamuses and whales, because it counteracts the buoyancy of their lungs and thus enables the organism to maintain a neutral buoyancy more efficient for swimming. Khirtharia is a raoellid that lived during the early Lutetian age. It is most similar to Metkatius in that it had bunodont teeth. As a raoellid, Khirtharia was relatively small, although there was large interspecific variety in size. Khirtharia''Khirtharia dayi''
Khirtharia dayi is the type and smallest species of Khirtharia, and one of the two smallest species of Raoellidae as a whole. Within K. dayi, there are two similar but distinct morphs: a more common one with relatively small molars and the other, more rare, one with relatively large molars.By being in the same genus, K. dayi
For the upper dentition of K. dayi, the first premolar is single-rooted, while the second is double-rooted. The second premolar is narrow and non-molarized; in life it would have appeared similar to a canine. The tooth is widest posteriorly because of a relatively large postero-lingual shelf. The third premolar is similar to the second; it is non-molarized and has a postero-lingual shelf. However, the third molar was slightly larger and there were large vertical grooves. The fourth premolar represents a transition from the canine-like first to third premolars to the molars. There are only two cones on the tooth, both situated in the front portions. Because of this, the posterior section of the tooth is low and flattened. The cone on the labial side of the tooth is larger than the protocone, which it is connected to by a ridge. The first lower molar is square-shaped. There are four large cusps which are rounded; they were likely used for crushing plant matter. The paracone is the largest cusp while the hypocone is the smallest. The first molar has large crests on the front and back cusps, while the outer ridge of teh tooth is fairly weak, giving it the illusion that it is wider than it is long. The second lower molar is significantly larger than the first and, as opposed to being square in shape, is trapezoidal. Cingulum are less apparent than the first molar. The second molar is has bulbous cusps. As with the first molar, the paracone is the largest of the cusps.While the first and second premolars were not preserved, Ranga Rao postulated that the first lower premolar was single-rooted while the second premolar was double-rooted. The third premolar is large and triangular, with prominent cingulum. The fourth premolar is slightly larger than the third. It is more premolariform than the upper fourth premolar. The lower molars of Khirtharia lack the paraconid. The lower molars are highly bunodont. There is a large ridge connecting the protocoled and metaconid and a large ridge connecting the hypoconid and entoconid. The largest molar is the third.