Saxonella(Plesiadapiformes: ?Primates) in North America:S. naylori, sp. nov., from the late Paleocene of Alberta, Canada

Saxonella Russell is a small plesiadapiform described in 1964 from incomplete dental and jaw remains occurring in Paleocene fissure fills at Walbeck, Germany. The first North American discovery of Saxonella was reported in 1984, based on an incomplete dentary with teeth from the late Paleocene Paskapoo Formation, Alberta, nearly 10,000 km from the Walbeck site; since then, several additional Paskapoo specimens have been collected. The Canadian fossils represent a new species evidently more primitive than the Walbeck S. crepaturae. In the new species, both p3 and p4 are bladelike teeth (p3 is the larger), in contrast with S. crepaturae, in which p4 is smaller relative to p3 and its crown rounded. The new fossils include three incomplete maxillaries that together preserve P2–4, M1–3; these are the only articulated upper dentitions of Saxonella now known. A long diastema separates P2, which is small and peg-like, from the next more anterior tooth, which is undiscovered. P3 is the largest cheek-tooth and is highly specialized, showing an unusually expanded anterior (parastylar) lobe, which occluded with the plagiaulacoid p3. In its entirety, the dentition of Saxonella makes up a mosaic of primitive, convergent, and uniquely specialized characters that conforms with Rose's (1975) suggestion that the genus is best classified in its own family within the Plesiadapiformes.