- suborder: Strepshirini
- superfamily: Adapoidea
- family: Notharctidae
- subfamily: Notharctinae
Notharctus tenebrosus has a fused mandibular symphysis and molar teeth with well-developed shearing crests (Fleagle, 1999). The incisors of this species are peg-like in form (Martin, 1990). This species has canines that are sexually dimorphic (Fleagle, 1999). The upper molars of this species have a psuedohypocone (Martin, 1990). The snout of this species is moderately long, with a long premaxillary bone (Fleagle, 1999). This species has a lacrimal bone that is positioned at the end of the orbit and not anterior to it as found in extant lemurs (Fleagle, 1999). The vertebral formula of this species is 7 cervicals, 12 thoracics, 8 lumbars, 3 sacrals, and 19+ caudals (MacLarnon, 1987; cited in Martin, 1990). This species has long hindlimbs, trunk, and tail (Fleagle, 1999). On the hands and feet the pollex and hallux are large and opposable, and the digits are long and possess nails (Fleagle, 1999). On the foot the calcaneus is relatively short (Fleagle, 1999). This species has an average body mass of 4.2 kilograms (Fleagle, 1999).
Notharctus tenebrosus lived in North America and occurred during the middle Eocene (Fleagle, 1999).
Based on dental morphology this species most likely had a folivorous diet (Fleagle, 1999).
Based upon limb bone morphology this species most likely moved by arboreal quadrupedalism and leaping (Fleagle, 1999).
Fleagle, J.G. 1999. Primate Adaptation and Evolution. Academic Press: San Diego.
MacLarnon, A.M. 1987. Size relationships of the spinal cord and associated skeleton in primates. PhD thesis, University of London.
Martin, R.D. 1990. Primate Origins and Evolution: A Phylogenetic Reconstruction. Princeton University Press: Princeton, New Jersey.
Last updated: November 13, 2001