would later become associated with Aenocyon dirus was found in mid-1854 in the bed of the Ohio River near Evansville, Indiana. The fossilized jawbone with cheek teeth was obtained by the geologist Joseph Granville Norwood from an Evansville collector, Francis A. Linck. The paleontologist Joseph Leidy determined that the specimen represented an extinct species of wolf and reported it under the name of Canis primaevus. Norwood's letters to Leidy are preserved along with the type specimen (the first of a species that has a written description) at the Academy of Natural Sciences of Philadelphia. In 1857, while exploring the Niobrara River valley in Nebraska, Leidy found the vertebrae of an extinct Canis species that he reported the following year under the name C.dirus. The name C.primaevus (Leidy 1854) was later renamed Canis indianensis (Leidy 1869) when Leidy found out that the name C.primaevus had previously been used by the British naturalist Brian Houghton Hodgson for the dhole. In 1876 the zoologist Joel Asaph Allen discovered the remains of Canis mississippiensis (Allen 1876) and associated these with C.dirus (Leidy 1858) and Canis indianensis (Leidy 1869). As so little was found of these three specimens, Allen thought it best to leave each specimen listed under its provisional name until more material could be found to reveal their relationship. In 1908 the paleontologist John Campbell Merriam began retrieving numerous fossilized bone fragments of a large wolf from the Rancho LaBrea tar pits. By 1912 he had found a skeleton sufficiently complete to be able to formally recognize these and the previously found specimens under the name C.dirus (Leidy 1858). Because the rules of nomenclature stipulated that the name of a species should be the oldest name ever applied to it, Merriam therefore selected the name of Leidy's 1858 specimen, C.dirus. In 1915 the paleontologist Edward Troxell indicated his agreement with Merriam when he declared C.indianensis a synonym of C.dirus. In 1918, after studying these fossils, Merriam proposed consolidating their names under the separate genus Aenocyon (from ainos, 'terrible' and cyon, 'dog') to become Aenocyon dirus, but at that time not everyone agreed with this extinct wolf being placed in a new genus separate from the genus Canis. Canis ayersi (Sellards 1916) and Aenocyon dirus (Merriam 1918) were recognized as synonyms of C.dirus by the paleontologist Ernest Lundelius in 1972. All of the above taxa were declared synonyms of C.dirus in 1979, according to