HARAMIYIDS AND TRIASSIC MAMMALIAN EVOLUTION

Isolated teeth referred to the family Haramiyidae are among the earlie st known fossil evidence of mammals. First discovered in European Late Triassic deposits a century and a half ago(1), haramiyids have been i nterpreted as related to multituberculates(2-7), a diverse and widespr ead lineage that occupied a rodent-like niche from the Late Jurassic t o the Early Tertiary. Nonetheless, haramiyid relationships have remain ed enigmatic(8,9) because the orientation and position of the teeth in the upper or lower jaw could not be determined with certainty; even t heir mammalian status has been questioned(10). The discovery of harami yid dentaries, a maxilla and other skeletal remains in the Upper Trias sic of East Greenland reveals haramiyids as highly specialized mammals with a novel pattern of puncture-crushing occlusion that differs dram atically from the grinding or shearing mechanisms of other Early Mesoz oic mammals.