Notharctus tenebrosus was an early primate

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...

 from the early 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...

, some 54-38 million years ago. Its fossil was found by Ferdinand V. Hayden in 1870 in southwestern Wyoming. When first found, Notharctus tenebrosus was thought to be a small pachyderm

Pachydermata

Pachydermata is an obsolete order of mammals described by Gottlieb Storr, Georges Cuvier and others, at one time recognized by many systematists...

 due to the concentration of pachyderm fossils in the area.

However, after Walter W. Granger

Walter W. Granger

Walter Willis Granger was an American vertebrate paleontologist who participated in important fossil explorations in the United States, Egypt, China and Mongolia.-Early life and career:...

's discovery of a nearly complete skeleton, also in Wyoming, it was firmly established as a primate. Notharctus tenebrosus most resembles modern-day Madagascar

Madagascar

The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...

 lemur

Lemur

Lemurs are a clade of strepsirrhine primates endemic to the island of Madagascar. They are named after the lemures of Roman mythology due to the ghostly vocalizations, reflective eyes, and the nocturnal habits of some species...

s.

Notharctus tenebrosus belonged to an extinct primate group known as Adapiformes

Adapiformes

Adapiformes are an extinct group of primitive primates.The adapiformes radiated throughout much of the northern continental mass, reaching as far south as northern Africa and tropical Asia. The adapiformes existed from the Eocene to the Miocene epoch...

 and fossils have been found in Europe

Europe

Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

 and North America

North America

North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

. Adapiform primates were among the first primates to exhibit a set of adaptations for life in the tree

Tree

A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...

s, such as grasping hand

Hand

A hand is a prehensile, multi-fingered extremity located at the end of an arm or forelimb of primates such as humans, chimpanzees, monkeys, and lemurs...

s, binocular vision

Binocular vision

Binocular vision is vision in which both eyes are used together. The word binocular comes from two Latin roots, bini for double, and oculus for eye. Having two eyes confers at least four advantages over having one. First, it gives a creature a spare eye in case one is damaged. Second, it gives a...

, and flexible backs.

"Notharctus" means false bear, while "tenebrosus" means dark or gloomy. N. tenebrosus is one of 5-12 species in the Notharctus

Notharctus

Notharctus was an early primate that inhabited Europe and North America 50 million years ago. Modern lemurs evolved from primates similar to this genus....

genus.

Morphology

Notharctus tenebrosus had a fused mandibular symphysis and molar teeth with well-developed shearing crests, while the incisors are peg-like in form. Notharctus tenebrosus had canine teeth that are sexually dimorphic. The upper molars of this species have a pseudohypocone and the snout

Snout

The snout, or muzzle, is the protruding portion of an animal's face, consisting of its nose, mouth, and jaw.-Terminology:The term "muzzle", used as a noun, can be ambiguous...

 is moderately long, with a long premaxillary bone. Notharctus tenebrosus had a lacrimal bone that was positioned at the end of the orbit but not anterior to it as found in extinct lemur

Lemur

Lemurs are a clade of strepsirrhine primates endemic to the island of Madagascar. They are named after the lemures of Roman mythology due to the ghostly vocalizations, reflective eyes, and the nocturnal habits of some species...

s. The vertebral formula of Notharctus tenebrosus is 7 cervicals, 12 thoracics, 8 lumbars, 3 sacrals, and 19+ caudals. Observing the fossils, Notharctus tenebrosus had long hindlimbs, trunk

Torso

Trunk or torso is an anatomical term for the central part of the many animal bodies from which extend the neck and limbs. The trunk includes the thorax and abdomen.-Major organs:...

, and tail

Tail

The tail is the section at the rear end of an animal's body; in general, the term refers to a distinct, flexible appendage to the torso. It is the part of the body that corresponds roughly to the sacrum and coccyx in mammals, reptiles, and birds...

. On the hands and feet, the pollex and hallux

Hallux

In tetrapods, the hallux is the innermost toe of the foot. Despite its name it may not be the longest toe on the foot of some individuals...

 are large and opposable, and the finger

Finger

A finger is a limb of the human body and a type of digit, an organ of manipulation and sensation found in the hands of humans and other primates....

s and toe

Toe

Toes are the digits of the foot of a tetrapod. Animal species such as cats that walk on their toes are described as being digitigrade. Humans, and other animals that walk on the soles of their feet, are described as being plantigrade; unguligrade animals are those that walk on hooves at the tips of...

s are long and possess nails, while on the foot the calcaneus is relatively short. Notharctus tenebrosus has an average body mass of 4.2 kilograms and was about 40 cm long without its tail.

Diet and locomotion

Based on dental morphology, Notharctus tenebrosus most likely had a folivorous diet.

Based upon limb bone morphology Notharctus tenebrosus most likely moved by leaping and was an arboreal quadruped

Quadruped

Quadrupedalism is a form of land animal locomotion using four limbs or legs. An animal or machine that usually moves in a quadrupedal manner is known as a quadruped, meaning "four feet"...

.

External links

• http://www.webcitation.org/query?url=http://www.geocities.com/CapeCanaveral/Lab/8932/Adapidae.html&date=2009-10-25+06:39:48
• http://www.ansp.org/museum/leidy/paleo/notharctus.php
• http://members.tripod.com/cacajao/notharctus_tenebrosus.html
• Mikko's Phylogeny archive