Hindlimb of a giant terrestrial bird from the upper Eocene, Fayum, Egypt

Eremopezus eocaenus Andrews, 1904 is a giant groundbird from upper Eocene d eposits of the Fayum, Egypt, which has hitherto been known from non-diagnos tic fragmentary material. New fossils collected from quarry L-41 of the Jeb el Qatrani Formation include two well-preserved distal tarsometatarsi and a n associated whole tarsometatarsus and distal tibiotarsus that allow a more precise evaluation of the phylogenetic position and tarsal function of Ere mopezus. Unlike most ratites, the distal tarsometatarsus has a patent dista l foramen and a slight hallucal digit. The trochlea for digits II and IV ar e only slightly reduced in size, are splayed to the right, and the heads la ck deep grooving. These features resemble the condition seen in Balaeniceps and Sagittarius, suggesting active use of the toes in grasping or manipula tion, rather than the condition in graviports and cursors, which have reduc ed medial and lateral trochleae often with distinct grooving of the heads. The limb is relatively long and gracile, another difference from graviports . There is no compelling evidence to link Eremopezus to any known ratite li neage, to the Phorusrhacoidea, or to the extinct predatory birds of the Eoc ene (e.g. Diatryma, Gastornis). We suggest that Eremopezus represents an en demic African group that independently attained large size and flightlessne ss.