title: Early Eocene fossils suggest that the mammalian order Perissodactyla originated in India.
abstract: Cambaytheres (Cambaytherium, Nakusia and Kalitherium) are recently discovered early Eocene placental mammals from the Indo-Pakistan region. They have been assigned to either Perissodactyla (the clade including horses, tapirs and rhinos, which is a member of the superorder Laurasiatheria) or Anthracobunidae, an obscure family that has been variously considered artiodactyls or perissodactyls, but most recently placed at the base of Proboscidea or of Tethytheria (Proboscidea+Sirenia, superorder Afrotheria). Here we report new dental, cranial and postcranial fossils of Cambaytherium, from the Cambay Shale Formation, Gujarat, India (~54.5 Myr). These fossils demonstrate that cambaytheres occupy a pivotal position as the sister taxon of Perissodactyla, thereby providing insight on the phylogenetic and biogeographic origin of Perissodactyla. The presence of the sister group of perissodactyls in western India near or before the time of collision suggests that Perissodactyla may have originated on the Indian Plate during its final drift toward Asia.
authors.affiliation: Center for Functional Anatomy &Evolution, Johns Hopkins University School of Medicine, 1830 E. Monument Street, Baltimore, Maryland 21205, USA.
authors.forename: Kenneth D
authors.initials: KD
authors.lastname: Rose
authors.affiliation: Department of Biological Sciences, Rowan University, Glassboro, New Jersey 08028, USA.
authors.forename: Luke T
authors.initials: LT
authors.lastname: Holbrook
authors.affiliation: Department of Geology, H.N.B. Garhwal University, Srinagar 246175, Uttarakhand, India.
authors.forename: Rajendra S
authors.initials: RS
authors.lastname: Rana
authors.affiliation: Wadia Institute of Himalayan Geology, Dehradun 248001, Uttarakhand, India.
authors.forename: Kishor
authors.initials: K
authors.lastname: Kumar
authors.affiliation: Center for Functional Anatomy &Evolution, Johns Hopkins University School of Medicine, 1830 E. Monument Street, Baltimore, Maryland 21205, USA.
authors.forename: Katrina E
authors.initials: KE
authors.lastname: Jones
authors.affiliation: Center for Functional Anatomy &Evolution, Johns Hopkins University School of Medicine, 1830 E. Monument Street, Baltimore, Maryland 21205, USA.
authors.forename: Heather E
authors.initials: HE
authors.lastname: Ahrens
authors.affiliation: Research Unit Palaeontology, Ghent University, Krijgslaan 281-S8, B-9000 Ghent, Belgium.
authors.forename: Pieter
authors.initials: P
authors.lastname: Missiaen
authors.affiliation: Department of Geology, Panjab University, Chandigarh 160014, India.
authors.forename: Ashok
authors.initials: A
authors.lastname: Sahni
authors.affiliation: Operational Directorate Earth &History of Life, Royal Belgian Institute of Natural Sciences, Rue Vautier 29, B-1000 Brussels, Belgium.
authors.forename: Thierry
authors.initials: T
authors.lastname: Smith
mesh_terms: D000818:Animals; D005075:Biological Evolution; D005580:Fossils; D007194:India; D010163:Paleontology; D010527:Perissodactyla; D010802:Phylogeny; D012886:Skull