Khirtharia

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. 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. 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 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. which was corroborated by Sahni and Khare in 1972 and Gingerich in 1977. After the results of a phylogenetic analysis in 2012 by Orliac and Ducrocq, it was determined that Khirtharia, along with Metkatius, were the most derived members of Raoellidae. Raoellidae is widely considered to be the sister group to Cetacea (whales), and thus Khirtharia is closely related to cetaceans, but not a cetacean itself. == Description ==

Raoellids were a group of mammals closely related to cetaceans. They were generally small and semiaquatic. Khirtharia dayi Khirtharia dayi is the type and smallest species of Khirtharia, and one of the two smallest species of Raoellidae as a whole. The jugal bone connects to the maxilla above the second molar. The internal nares connect to the throat just after the third molar. There is a large parietal crest, although a relatively minor sagittal one. The incisors are caniniform and raptorial, likely adapted to seizing prey. Khirtharia major Khirtharia major is a possible species of Khirtharia known only from two molars. It is the largest species of Khirtharia and the largest raoellid as a whole; it is twice the size of Indohyus indirae. It is different from all other species of Khirtharia in that it has an elongated third molar, larger hypocone, and a variety of other small morphological differences. == Phylogeny ==

After a phylogenetic analysis by Orliac and Ducrocq (2012), they found that a molar of a raoellid from China was most closely related to Khirtharia than to Indohyus, and subsequently reclassified it from I. major to K. major. The study did not include Rajouria due to Rajouria only being described after this study was published.It found that Raoellidae is monophyletic. Kunmunella and Indohyus, are the most basal members of Raoellidae, with the relationship between them uncertain, and then Metkatius and Khirtharia. Rana et al. (2021), in their description of Rajouria, completed a phylogenetic analysis of Raoellidae. They used a near identical method as the previous Orliac and Ducrocq, although added in the material for Rajouria and added two extra characters related to the teeth. This study also placed Haqueina outside of Raoellidae.Rajouria is the most basal member of the family. Kunmunella and Indohyus are both equally basal members of Raoellidae, and the exact relationship between them is uncertain. Metkatius and Khirtharia are most closely related to each other and are the most derived members of Raoellidae. == Paleobiology ==

Diet Khirtharia's diet is largely based upon its dental structure. Khirtharia, as the most bunodont of any raoellid, was likely the most omnivorous (as opposed to the other, primarily herbivorous, raoellids). This is because bunodonty is characteristic of omnivorous taxa. Additionally, Khirtharia had caniniform incisors suited for catching and holding struggling prey. Initially, it was thought that Khirtharia was more terrestrial than Indohyus due to oxygen isotope information, but the thickening of parts of the skull in Khirtharia provides evidence that it was more similar to Indohyus in terms of how aquatic it was. This can be evidenced with the fact that it had sideways facing eyes, which is an adaptation found primarily in prey to help them detect predators more easily. Khirtharia, along with all other raoellids, would probably try to evade predators by hiding in bodies of water, similar to the modern day chevrotain. == Paleoecology ==

, a small perissodactyl which shared some of its range with Khirtharia''. Khirtharia inhabited Kashmir, northern India, about 50 million years ago, at the same time as the beginning of the formation of the Himalayan mountains. India was an island subcontinent during the temporal range of Khirtharia, and the process of collision and subsequent mountain building of the Himalayas had only just begun during Khirtharia's emergence. At the time, Kashmir was a wet, tropical flood basin with many shallow marine formations; this is explained by the fact it was an equatorial coastal region during the Early Eocene Climatic Optimum, where temperatures were significantly higher than normal. This led to the global climate being a "greenhouse Earth", meaning that there were no year-round ice caps. There were likely large rainforests and mangrove forests along the coastlines of northern India at the time, coinciding with plankton blooms due to the extreme heat. The climate was very humid. == See also ==