page_title: Desmostylia
section_title: Classification
hierarchical_section_title: Desmostylia / Classification
caption_attribution_description: English: Neoparadoxia cecilialina Paleoparadoxiid skeleton at the Natural History Museum of Los Angeles County. 日本語: パレオパラドシキアの骨格
context_page_description: The Desmostylia are an extinct order of aquatic mammals that existed from the early Oligocene to the late Miocene.
  Desmostylians are the only known extinct order of marine mammals.
  The Desmostylia, together with Sirenia and Proboscidea, have traditionally been assigned to the afrotherian clade Tethytheria, a group named after the paleoocean Tethys around which they originally evolved. The relationship between the Desmostylia and the other orders within the Tethytheria has been disputed; if the common ancestor of all tethytheres was semiaquatic, the Proboscidea became secondarily terrestrial; alternatively, the Desmostylia and Sirenia could have evolved independently into aquatic mammals. The assignment of Desmostylia to Afrotheria has always been problematic from a biogeographic standpoint, given that Africa was the locus of the early evolution of the Afrotheria while the Desmostylia have only been found along the Pacific Rim. That assignment has been seriously undermined by a 2014 cladistic analysis that places anthracobunids and desmostylians, two major groups of putative non-African afrotheres, close to each other within the laurasiatherian order Perissodactyla.
context_section_description: The type species Desmostylus hesperus was originally classified from a few teeth and vertebrae as a sirenian by Marsh 1888, but doubts arose a decade later when more complete fossils were discovered in Japan. Osborn 1905 also proposed that they belonged to the Sirenia. One of the most comprehensive collections of desmostylian teeth was amassed by paleontologist John C. Merriam, who concluded on the basis of the molar structure and repeated occurrence in marine beds that the animals had been aquatic, and were probably sirenian.
  In 1926, the Austrian palaeontologist Othenio Abel suggested origins with monotremes, like the duck-billed platypus, and in 1933, he even created the order "Desmostyloidea", which he placed within the Multituberculata. Abel died shortly after World War II, and his classification won few supporters and has been ignored since.
  Because desmostylians were originally known only from skull fragments, teeth, and bits of other bones, general agreement was that they had had flippers and a fin-like tail. The discovery of a complete skeleton from Sakhalin Island in 1941, however, showed that they possessed four legs, with bones as stout as a hippopotamus', and justified the creation of a new order for the desmostylians, described by Reinhart 1959.
  A major find was announced in October 2015 after scientists examined an extensive group of giant, tusked, quadruped, marine mammal fossils. This northernmost to date species discovery had been unearthed during excavation for the construction of a school in Unalaska, in the Aleutian Islands. A rendition of a group was drawn by Alaskan artist Ray Troll.
  Despite their similarities to manatees and elephants, desmostylians were entirely unlike any living creatures. Douglas Emlong's 1971 discovery of the new genus Behemotops from Oregon showed that early desmostylians had more proboscidean-like teeth and jaws than later ones. Despite this discovery, their relationships to manatees and proboscids remain unresolved. The analysis of Cooper et al. (2014) indicates the similarities with manatees and elephants may be a result of convergence and that they may instead be basal perissodactyls.
  Barnes 2013 proposed a new classification of Paleoparadoxiidae:
  Order Desmostylia Reinhart, 1953
  Family Paleoparadoxiidae Reinhart, 1959
  Subfamily Behemotopsinae (Inuzuka, 1987)
  Behemotops Domning, Ray, and McKenna, 1986
  Behemotops proteus Domning, Ray, and McKenna, 1986 (including Behemotops emlongi Domning, Ray, and McKenna, 1986)
  Behemotops katsuiei Inuzuka, 2000b
  Subfamily Paleoparadoxiinae (Reinhart, 1959)
  Archaeoparadoxia
  Archaeoparadoxia weltoni (Clark, 1991)
  Paleoparadoxia Reinhart, 1959
  Paleoparadoxia tabatai (Tokunaga, 1939), (= Paleoparadoxia media Inuzuka, 2005)
  Neoparadoxia Barnes 2013
  Neoparadoxia repenningi (Domning and Barnes, 2007)
  Neoparadoxia cecilialina Barnes 2013
caption: Neoparadoxia cecilialina on display at the Natural History Museum of Los Angeles County
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