Carodnia is the largest mammal known from the Eocene of South America. It was heavily built and had large canines and cheek teeth with a crested pattern like the uintatheres to which it can be related.[3] In life, it would have been a tapir-sized animal. It bore strong resemblances to dinoceratans, although without tusks or ossicones. When George Simpson first described Carodnia, he cited the genus name as being derived from the Tehuelche word for thunder "carodn".[5]
Description
Size comparison between a human and C. vieirai
Simpson noted that Carodnia resembles the primitive uintathereProbathyopsis. Although Paula Couto also made the same favorable comparison, he placed Carodnia in the new order Xenungulata. Gingerich 1985 concluded that Probathyopsis shares several dental characteristics with Carodnia, but that in the latter the anterior dentition of is more reduced, the second lower and upper premolars are enlarged and pointed, and that the first and second molars are more lophodont. Gingerich thought the differences could justify a separate family for Carodnia but proposed that it should be included in Probathyopsis,Cifelli 1983 grouped Carodnia with Pyrotheria but later concluded that this was a mistake.[6]
Carodnia is characterized by bilophodont[explain 1] first and second molars and more complex lophate[explain 1] third molars, which suggests possible links to pyrotheres, uintatheres, and even arctocyonids. The bones of the foot are short and robust and the digits terminate in broad, flat, and unfissured hoof-like unguals, unlike any other known meridiungulate.[7]
C. feruglioi and C. cabrerai, from the Riochican in the SALMA classification of Patagonia,[6] are known from only a few dental remains. C. vieirai (from the Itaboraian SALMA of Itaborai)[6] is known from much more complete dental, cranial, and postcranial remains including an almost complete mandible, many vertebrae, and several partial leg bones.[8]
When Simpson 1935 first described Carodnia and Ctalecarodnia, the former was known only from a left lower molar which was lacking in the latter, making a comparison very difficult. Paula Couto 1952, based on considerably more complete remains, concluded that the molars and premolars of both are indistinguishable and therefore reduced Ctalecarodnia to a synonym. Paula Couto also noted that the dentition of C. cabrerai and C. feruglioi are similar except in size, and that C. feruglioi can be a juvenile C. cabrerai, but nevertheless left them as two distinct species.[9]
^Simpson, George Gaylord (1935). "Descriptions of the oldest known South American mammals, from the Río Chico Formation". American Museum Novitates. Publications of the Scarritt Expeditions, no. 24 (793). hdl:2246/2125. OCLC44083494.
Paula Couto, Carlos, de (1952). "Fossil mammals from the beginning of the Cenozoic in Brazil. Condylarthra, Litopterna, Xenungulata, and Astrapotheria". Bulletin of the American Museum of Natural History. 99: 355–394. hdl:2246/417. OCLC18189741.((cite journal)): CS1 maint: multiple names: authors list (link)
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