''Hesperolemur'' is a genus of

adapiform Adapiformes is a group of early primates. Adapiforms radiated throughout much of the northern continental mass (now Europe, Asia and North America), reaching as far south as northern Africa and tropical Asia. They existed from the Eocene to the M ...

primate Primates are a diverse order of mammals. They are divided into the strepsirrhines, which include the lemurs, galagos, and lorisids, and the haplorhines, which include the tarsiers and the simians (monkeys and apes, the latter including huma ...

that lived in the middle

Eocene The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...

(49-37 million years ago) of southern

California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...

. It is an immigrant taxa which appears to be most closely related to the earlier European forms of ''

Cantius ''Cantius'' is a genus of adapiform primates from the early Eocene of North America and Europe. It is extremely well represented in the fossil record in North America and has been hypothesized to be the direct ancestor of Notharctus in North Amer ...

''. It was approximately in weight and was the last surviving

notharctine Notharctinae is an extinct subfamily of primates that were common in North America during the early and middle Eocene (55-34 million years ago). The six genera that make up the group (''Cantius'', ''Pelycodus'', ''Copelemur'', ''Hesperolemur'', ...

species, probably because of its position in the refugia that existed in southern California during the climate deterioration at the end of the middle Eocene. There are no later taxa that appear to have derived from ''Hesperolemur''. The weak but present development of mesostyles and pseudohypocone link ''Hesperolemur'' to ''Cantius''. Morphologically, ''Hesperolemur'' is distinct from other notharctine taxa in having a partially fused ectotympanic anulus in the auditory bulla, no stapedial

artery An artery (plural arteries) () is a blood vessel in humans and most animals that takes blood away from the heart to one or more parts of the body (tissues, lungs, brain etc.). Most arteries carry oxygenated blood; the two exceptions are the pul ...

, and no lower molar paraconids. As the specimen used to make these analyses was badly damaged, others have argued against the existence of such differences and move ''Hesperolemur'' to a species of ''Cantius'', ''Cantius actius.''

References

Literature cited

* *Fleagle, J. G. 1999. Primate Adaptation and Evolution. San Diego, Academic Press.
Mikko's Phylogeny Archive
*Gebo, DL. 2002. Adapiformes: phylogeny and adaptation. The Primate Fossil Record. Cambridge University Press *Godinot, M. A Summary of Adapiform Systematics and Phylogeny. Folia Primatologica, 1998 *Gunnel, GF. New notharctine (primates, adapiformes) skull from the Uintan (middle Eocene) of San Diego County, California. American Journal of Physical Anthropology, 98:4. 1995. *Rose, KD et al. Skull of Early Eocene Cantius abditus (Primates:Adapiformes) and its phylogenetic implications, with a reevaluation of "Hesperolemur" actius. Am J Phys Anthropol. 1999 Aug;109(4):523-39. {{Taxonbar, from=Q5745976 Prehistoric strepsirrhines Eocene primates Prehistoric primate genera Fossil taxa described in 1995 Eocene mammals of North America