A new species of Numidotherium (Mammalia: Proboscidea) from the Eocene of Libya and the early phylogeny of the Proboscidea

ABSTRACT

Proboscidean material collected from the upper Eocene of Dor el Talha, southern Libya, has been considered to include two species of the genus Barytherium, one large species referable to Barytherium grave of the Fayum, Egypt and a small undescribed species. Study of the fragmentary, small Libyan species indicates that this material is better referred to the genus Numidotherium and the new species Numidotherium savagei is erected. Recent advances in knowledge of numidothere anatomy are then analyzed in a cladistic treatment of basal proboscidean genera using dental, cranial, and postcranial data. The phylogenetic hypothesis generated differs from pervious analyses in the relative positioning of Numidotherium and Moeritherium. Aspects of cranial, dental, and postcranial anatomy are shown to be primitive in Numidotherium relative to Moeritherium and all other proboscideans. Numidotherium is therefore considered to be the least transformed of basal proboscideans. The traditional use of Moeritherium as the closest approximation to the proboscidean ancestral condition in interordinal phylogenetic analysis is shown to be flawed. Moeritherium is better treated as an early specialized offshoot of the lineage leading to more derived, graviportal proboscideans.