A Guide to Adapidae Family

Extinct primate family that has come to include a plethora of European Eocene primates ranging in size from as small as a mouse (Anchomomys) to as big as a large cat (Leptadapis). According to studies of body size and molar shearing-crest development, the larger forms (Adapis, Leptadapis, Caenopithecus, Protoadapis, Europolemur) were probably folivorous, whereas the smaller forms (e.g., Periconodon, Anchomomys, Microadapis, Agerina), and possibly Pronycticebus as well, were probably insectivorous, with the latter three taxa perhaps also including fruit in their diet.
Although Adapidae is associated here with Notharctidae, it is only within the former group that the ancestry of modern strepsirhines has traditionally been sought.
The genus Adapis, which gives its name to the family Adapidae as well as to taxa of other ranks, was described in 1821 by the French paleontologist G.Cuvier, who thought it might be either a pachyderm or an artiodactyl. Despite this “false start,” Adapis claims the distinction of being the first fossil primate to be studied. Since its discovery, Adapis has become one of the best known of all European fossil primates: It is a particularly dominant mammal in collections from the limestone deposits of the Franco-Belgian Basin. The genus Leptadapis, the largest of the adapids, used to be included as a species of Adapis (A. magnus), but the genus Adapis is now reserved for the original form, A. parisiensis, and perhaps one other species of comparable size. In 1912, the Swiss paleontologist H.G.Stehlin published a monographic study of Adapis (including “Adapis” magnus). In comparing it especially with the North American Notharctus, he concluded that, while the Old and New World taxa may somehow be related, differences warranted distinction at the family level between the groups they represented.
This matter was addressed by the American paleontologist W.K.Gregory in his 1920 work on Notharctus, in which he argued that differences between Adapis and Notharctus in skull shape and particularly in dental elaboration (more in the latter taxon), while real, were no less profound than differences that existed among miacids, an assemblage of extinct but diverse carnivores that all paleontologists seemed to agree belonged in the same family. Thus, Gregory concluded that it was appropriate to group the European taxa in the subfamily Adapinae and the North American forms in Notharctinae and to subsume both in the family Adapidae. The common ancestor of both adapid subfamilies was taken to be the Early Eocene Pelycodus (then known only from North America but subsequently also from Europe), from which Gregory believed that both the geologically younger Adapis and Notharctus could have evolved.
This basic phylogenetic scheme was not altered in the ensuing few decades, but largely through the studies of P. Robinson and C.L.Gazin in the 1950s, Stehlin’s suggestion that the European and the North American taxa should be separated at the family level was revived. Thus, two alternative classificatory schemes have been applied to the family Adapidae: most recently, E.L.Simons and F.S.Szalay and E. Delson have preferred Gregory’s subfamily divisions, while in this volume, for example, the distinctiveness of the two groups is maintained at the family level.