Oligokyphus ("few cusps") is an extinct genus of herbivorous tritylodontid cynodont known from the Late Triassic to Early Jurassic of Europe, Asia and North America. Discovery and naming Oligokyphus was named by Edwin Hennig in 1922 on the basis of two teeth from Württemberg, Germany. The name of the genus is derived from Greek "few" and "hump", and is a calque of Paucituberculata, the group in which Oligokyphus was initially classified, from Latin into Greek. Like Tritylodon, Oligokyphus was originally classified as a mammal. Hennig initially recognized two species, which he named Oligokyphus triserialis and Oligokyphus biserialis based on the number of rows of cusps, though he acknowledged this distinction as provisional. The next discoveries of Oligokyphus were made in the United Kingdom. The German paleontologist Walter Georg Kühne traveled to the United Kingdom in 1938 with the goal of collecting early mammal specimens. The outbreak of World War II led to Kühne's internment on the Isle of Man, during which time he prepared and studied the collected material. Kühne initially identified the specimens as Tritylodon. His discovery that the specimens lacked the dentary-squamosal jaw joint, at the time viewed as the defining characteristic of mammals, led him to conclude that tritylodontids were "mammal-like reptiles", though he recognized that they were close to the origin of mammals. Kühne's detailed description of the material was published in 1956, and made Oligokyphus the best-known tritylodontid. Kühne regarded two different size classes of adult as being present. Though he acknowledged the differences could be due to sexual dimorphism, he proposed that they represented two distinct species, which he named Oligokyphus major and Oligokyphus minor. In 1985, the genus was reported from the Early Jurassic Kayenta Formation in the United States. In 1994, the species O. lufengensis was described from the Lower Jurassic Lufeng Formation of China. In 2015, indeterminate remains of the genus were described from the McCoy Brook Formation of eastern Canada, dating to the latest Triassic (Rhaetian). Description Oligokyphus were relatively small tritylodontids, with a skull up to 90 mm long and an estimated body mass of 3.4 kg. There may have been some sexual dimorphism in size. Skull and jaw The teeth of the upper and lower jaw contain bump rows that fit together perfectly in order to maintain an accurate bite. Oligokyphus had a face similar to that of modern mammals, although there were differences in the cheekbones and