Your Daily Fossil

Notharctus

Mounted specimen on display at the American Museum of Natural History, NYC

Reconstruction by Jay Matternes 

When: Early to mid Eocene (~56 to 46 million years ago)

Where: North America

What: Notharctus is a fossil primate. It may seem odd to talk of a primate in North America, but this continent was the home to a diverse suite of primates in the Paleocene and Eocene, including some of the oldest. The lush sub-tropical North American forests of this time were host to an extreme amount of diversity, giving rise to many lineages that are no longer found on this continent. Notharctus lived in the tree tops of the Eocene topical forests, leaping from tree to tree. It was joined in these trees by relatives of carnivorans, such as Vulpavus. Notharctus, and many other arboreal animals, went extinct in the middle Eocene when the forests began to vanish as the climate became cooler and drier.    

Living primates are divided into two main groups, the Strepsirrhini (lemurs, Lorises, and galagos) and the Haplorhini (tarsiers, monkeys,  and apes). Notharctus and its kin (grouped as adapids) are more closely related to the strepsirrhines than to the haplorhines, and thus they are sometimes called ’ancient lemurs’. One fossil closely related to Notharctus made the media rounds a couple of years ago: Darwinius aka Ida. This fossil primate had a high impact in the popular science media, it even had its own TV special! Much of this media, based on the original publication of Darwinius, said that Ida was an important ‘missing link’ and bridged the gap from primitive primates to the haplorhines. This is just not true. Darwinius is an amazing looking fossil, yes, but it acutally provided very little novel information regarding fossil primate anatomy. Notharctus has been well known and studied for over 100 years, and its morphology clearly points to a closer link to lemurs than to monkeys. Subsequent analyses of Darwinius, by a different team of researchers than those that published the specimen at first, have supported the traditional view. Adapids are firmly placed on the lineage leading to lemurs, not the one leading to apes.