. "Arctostylopida"@en . . . "Arctostylopida is an extinct order of placental mammals from the Late Palaeocene of Eastern Asia and North America. All arctostylopid specimens in North America have been referred to the genus Arctostylops.They are animals of uncertain affinities to other groups and it was believed that they may be related to 'ungulates'. Originally they were considered to be northern relatives of South American notoungulates, specifically Notostylopidae."@en . .