Zhelestidae is a lineage of extinct eutherian mammals. Bandicoots are also the only metatherian marsupials that have placentas similar to eutherian mammals. "Schowalteria" is a taeniodont eutherian. The genus is viviparous, having a highly evolved placenta that resembles that of eutherian mammals. In the 2000s understanding of the relationships among eutherian mammals has experienced a virtual revolution. Cimolesta is an extinct order of non-placental eutherian mammals. Other finds in the area include specimens of "Velociraptor" and eutherian mammals. Euarchonta and Glires together form the Euarchontoglires, one of the four Eutherian clades. Pantodonta is an extinct suborder (or, according to some, an order) of eutherian mammals. This fossil is thought to be the earliest eutherian ancestor. The evolution of color vision in primates is unique among most eutherian mammals. The group may have become extinct due to competition with eutherian mammals, such as rodents. Instead, nearly all known eutherian and metatherian fossils belong to other groups. Marsupial torpor differs from non-marsupial mammalian (eutherian) torpor in the characteristics of arousal. This was South America's first eutherian carnivore.