Notostylops ("south pillar face") is a genus of extinct South American notoungulates from Eocene Argentina. Fossils of the genus have been found in the Sarmiento, Casamayor, Andesitas Huancache and Koluel Kaike Formations.
Notostylops was a very generalised animal, very similar to the first eutherians and ungulates. It would have superficially resembled a marmot or a wombat and is suspected to have browsed on low-growing plants. It was probably adapted to a fairly wide range of ecological niches, but its robustness indicates it had some digging adaptations. Its tall skull housed rodent-like incisor teeth. Notostylops incisors lacked complex, decussating enamel prisms, instead possessing radial enamel. The endocast of N. murinus had a volume of 9,807 mm<sup>3</sup>, with the volume of the olfactory bulbs being 629 mm<sup>3</sup>. Notostylops had a degree of cranial flexure of 34ÃÂ. Notostylops was about long.