The Origin and Status of the Mammalian Order Tillodontia

The early Tertiary group Tillodontia is shown to have been derived from or near the middle Paleocene arctocyonid “Claenodon” procyonoides, which may be related also to the Tricuspiodontidae. The nature of mammalian orders is discussed, with the conclusion that the Tillodontia are best placed as a suborder of the Condylarthra.