Hesperolemur
Encyclopedia
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.
Primate
A primate is a mammal of the order Primates , which contains prosimians and simians. Primates arose from ancestors that lived in the trees of tropical forests; many primate characteristics represent adaptations to life in this challenging three-dimensional environment...
that lived in the middle Eocene
Eocene
The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...
(55-34 million years ago) of southern California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
. It is an immigrant taxa which appears to be most closely related to the earlier European forms of Cantius
Cantius
Cantius was a genus of adapiformes primate that lived in the Eocene....
. 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
Hypocone
The hypocone is the name for a main cusp found on the molars of the upper dentition of hominids. It is found on the distal lingual side of the tooth. It fits into the grooves of the lower dentition and is an adaptation for the overall grinding and tearing of foods using the occlusal of the tooth...
link Hesperolemur to Cantius. Morphologically, Hesperolemur is distinct from other notharctine taxa in having a partially fused ectotympanic
Ectotympanic
The ectomtympanic is a bone that suspends the eardrum in mammals. It is homologus with the angular....
anulus in the auditory bulla
Auditory bulla
The auditory bulla is a hollow bony structure on the ventral, posterior portion of the skull of placental mammals that encloses parts of the middle and inner ear. In most species, it is formed by the tympanic part of the temporal bone.In extant primates, the structure is found in tarsiers,...
, no stapedial artery
Artery
Arteries are blood vessels that carry blood away from the heart. This blood is normally oxygenated, exceptions made for the pulmonary and umbilical arteries....
, and no lower molar
Molar (tooth)
Molars are the rearmost and most complicated kind of tooth in most mammals. In many mammals they grind food; hence the Latin name mola, "millstone"....
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.