Reassessment of Lower EoceneSeggeurius amourensis: aspects of primitive dental morphology in the mammalian order Hyracoidea

Abstract

New lower dental material of the fossil hyracoid mammal,Seggeurius amourensisCrochet, 1986, from Eocene deposits of the Southern Atlas in Algeria, has prompted a reevaluation of the genus. The dentition as a whole is first described in detail, thus providing a more precise characterization of the genus than has hitherto been available. Peculiarities, particularly in upper molar morphology, are sufficient to uphold a generic distinction. However, based largely on lower molar morphologySeggeurius amourensisis transferred from the subfamily Geniohyinae to Saghatheriinae. In the upper molars, absence of a postmetacrista and the presence of a preprotocrista continuous with the parastyle are interpreted as primitive features in hyracoids. In the lower molars, extreme reduction of the paracristid and the presence of a mesoconid are also considered primitive for hyracoids. These features together with small size, bunodonty, low crown height, and very simple premolar morphology indicate thatSeggeurius amourensisis the most primitive hyrax yet recovered.