Notharctus

Notharctus is a genus of adapiform primate that lived in North America and Europe during the late to middle Eocene.^[1]

N. tenebrosus (left) compared to Plesiadapis cookei (right), a plesiadapiform. Both come from Eocene Wyoming, though the latter is slightly geologically older (Museum of Natural Sciences, Brussels).

Notharctus Temporal range: Early-Mid Eocene (Wasatchian-Uintan) ~50.3–40.4 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Notharctus tenebrosus
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Primates
Suborder:	Strepsirrhini
Family:	†Notharctidae
Subfamily:	†Notharctinae
Genus:	†Notharctus Leidy, 1870
Species
†N. pugnax †N. robustior †N. tenebrosus †N. venticolus
Synonyms
Hipposyus Leidy 1872 Limnotherium Marsh 1871 Telmalestes Marsh 1872 Thinolestes Marsh 1872 Tomitherium Cope 1872

The body form of Notharctus is similar to that of modern rats. Its fingers were elongated for clamping onto branches, including the development of a thumb. Its spine is flexible and the animal was about 40 centimetres (16 in) in length, excluding the long tail.^[2]

There were at least four different Notharctus species.^[1] Fossils from at least seven other potential species have also been discovered.^{[citation needed]}

N. osborni skull