The Indian rhinoceros (Rhinoceros unicornis), or Indian rhino for short, also known as the greater one-horned rhinoceros or great Indian rhinoceros, is a rhinoceros species native to the Indian subcontinent. It is listed as Vulnerable on the IUCN Red List, as populations are fragmented and restricted to less than . Moreover, the extent and quality of the rhino's most important habitat, the alluvial Terai-Duar savanna and grasslands and riverine forest, is considered to be in decline due to human and livestock encroachment. As of August 2018, the global population was estimated to comprise 3,588 individuals, including 2,939 individuals in India and 649 in Nepal. Kaziranga National Park alone had an estimated population of 2,048 rhinos in 2009. Pobitora Wildlife Sanctuary in Assam has the highest density of Indian rhinos in the world with 84 individuals in an area of in 2009. Indian rhinos once ranged throughout the entire stretch of the Indo-Gangetic Plain, but excessive hunting and agricultural development reduced its range drastically to 11 sites in northern India and southern Nepal. In the early 1990s, between 1,870 and 1,895 Indian rhinos were estimated to have been alive. Since then, numbers have increased due to conservation measures taken by the government. However, poaching remains a continuous threat, as more than 150 Indian rhinos were killed in Assam by poachers between 2000 and 2006. Nearly 85% of the global Indian rhinoceros population is concentrated in Assam, where Kaziranga National Park contains 70% of rhino population. Etymology The generic name Rhinoceros is a combination of the ancient Greek words ῥίς (ris) meaning "nose" and κέρας (keras) meaning "horn of an animal". The Latin word ūnicornis means "one-horned". Taxonomy Rhinoceros unicornis was the scientific name used by Carl Linnaeus in 1758 who described a rhinoceros with one horn. As type locality, he indicated Africa and India. The Indian rhinoceros is monotypic. Several specimens were described since the end of the 18th century under different scientific names, which are all considered synonyms of Rhinoceros unicornis today: R. indicus by Cuvier, 1817 R. asiaticus by Blumenbach, 1830 R. stenocephalus by Gray, 1867 R. jamrachi by Sclater, 1876 R. bengalensis by Kourist, 1970 Evolution Ancestral rhinoceroses first diverged from other perissodactyls in the Early Eocene. Mitochondrial DNA comparison suggests the ancestors of modern rhinos split from the ancestors of Equidae around 50 million years ago. The extant family, the Rhinocerotidae, first appeared in the Late Eocene