An extinct order of early Cenozoic (about 65 to 40 million years ago) quadrupedal eutherian land mammals, represented by nine known genera, from the late Paleocene to middle Eocene of North America (Esthonyx (Azygonyx), Megalesthonyx, Trogosus, and Tillodon), early Paleocene to late Eocene of China (Lofochaius, Meiostylodon, Adapidium, Trogosus (Kuanchuanius)), middle Eocene of Pakistan (Basalina), and the early Eocene of Europe (Plesiesthonyx). Anchippodus, the first named tillodont genus (1868), based on a single left lower molar found in middle Eocene rocks of New Jersey, is a nomen dubium (it is not certain which species of tillodont is represented by this tooth) and may represent either Trogosus or Tillodon. An indeterminate tillodont incisor fragment found on Ellesmere Island demonstrates that tillodonts lived in what is now the Canadian High Arctic during the Eocene under much warmer conditions than exist there today.