Megaconus is an extinct genus of mammaliaforms from the Middle Jurassic Tiaojishan Formation of Inner Mongolia, China. The type and only species, Megaconus mammaliaformis (nicknamed Jurassic Squirrel), was first described in the journal Nature in 2013. Megaconus is thought to have been a herbivore that lived on the ground, having a similar posture to modern-day armadillos and rock hyraxes. Megaconus is a member of a group called Haramiyida. A phylogenetic analysis published along with its first description showed that haramiyidans originated before the appearance of , but an accompanying description of the haramiyidan Arboroharamiya in the same issue of Nature indicated that haramyidans were true mammals. If haramiyidans are not mammals, Megaconus would be one of the most basal ("primitive