''Hesperolemur'' is a genus of
adapiform primate
Primates is an order (biology), order of mammals, which is further divided into the Strepsirrhini, strepsirrhines, which include lemurs, galagos, and Lorisidae, lorisids; and the Haplorhini, haplorhines, which include Tarsiiformes, tarsiers a ...
that lived in the middle
Eocene
The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...
(49-37 million years ago) of
southern California
Southern California (commonly shortened to SoCal) is a geographic and Cultural area, cultural List of regions of California, region that generally comprises the southern portion of the U.S. state of California. Its densely populated coastal reg ...
. It is an immigrant
taxa
In biology, a taxon (back-formation from ''taxonomy''; : taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular name and ...
which appears to be most closely related to the
earlier European forms of ''
Cantius''. It was approximately in weight and was the last surviving
notharctine species, probably because of its position in the
refugia that existed in
southern California
Southern California (commonly shortened to SoCal) is a geographic and Cultural area, cultural List of regions of California, region that generally comprises the southern portion of the U.S. state of California. Its densely populated coastal reg ...
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
mesostyle
Many different terms have been proposed for features of the tooth crown in mammals.
The structures within the molars receive different names according to their position and morphology. This nomenclature was developed by Henry Fairfield Osborn i ...
s and
pseudohypocone link ''Hesperolemur'' to ''Cantius''. Morphologically, ''Hesperolemur'' is distinct from other notharctine taxa in having a partially fused
ectotympanic The ectotympanic, or tympanicum, is a bony structure found in all mammals, located on the tympanic part of the temporal bone, which holds the tympanic membrane (eardrum) in place. In catarrhine primates (including humans), it takes a tube-shape. ...
anulus in the
auditory bulla
The tympanic part of the temporal bone is a curved plate of bone lying below the squamous part of the temporal bone, in front of the mastoid process, and surrounding the external part of the ear canal.
It originates as a separate bone (tympanic b ...
, no
stapedial artery
An artery () is a blood vessel in humans and most other animals that takes oxygenated blood away from the heart in the systemic circulation to one or more parts of the body. Exceptions that carry deoxygenated blood are the pulmonary arteries in ...
, and no lower
molar paraconid
Many different terms have been proposed for features of the tooth crown in mammals.
The structures within the molars receive different names according to their position and morphology. This nomenclature was developed by Henry Fairfield Osborn i ...
s. 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
Notharctidae
Eocene primates
Monotypic prehistoric primate genera
Fossil taxa described in 1995
Eocene mammals of North America