Hesperolemur

Taxobox
name = "Hesperolemur actius"
fossil_range = Middle Eocene
regnum = Animalia
phylum = Chordata
classis = Mammalia
ordo = Primates
familia = Notharctidae
genus = "Hesperolemur"
species = "H. actius"
binomial = "Hesperolemur actius"
binomial_authority = Gunnell, 1995

"Hesperolemur actius" is an extinct primate that lived in the middle Eocene (55-34 million years ago) of southern California. It is an immigrant taxa which appears to be most closely related to the earlier European forms of "Cantius". It was approximately 4.5 kg in weight and was the last surviving notharctine 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, 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

Fleagle, J. G. 1999. Primate Adaptation and Evolution. San Diego, Academic Press.

[http://www.fmnh.helsinki.fi/users/haaramo/Metazoa/Deuterostoma/Chordata/Synapsida/Eutheria/Plesiadapiformes/plesiadapiformes.htm 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.