ABSTRACT
Classifications of the order Primates attract great attention because of their special relevance to human evolution. There are six "natural groups" of living Primates: malagasy lemurs; bush-babies, pottos and lorises; tarsiers; new world monkeys; old world monkeys; and apes and man. The chief points of contention have been: inclusion of the tree shrews with the Primates; ranking of the Tarsiiformes or the simians; the inclusion of various fossil groups; and the fine details of hominid evolution. The "ancestral Primate stock" is generally thought to be located in the Upper Cretaceous and/or Palaeocene, while the existing and subfossil Malagasy lemurs are thought to have been derived from a single stock isolated on Madagascar in early Eocene times primarily as a result of continental drift. The Eocene fossil Notharctidae, widely regarded as direct relatives of the Malagasy lemurs, probably came from a separate stock roughly contemporaneous with the hypothetical lemur/loris stock.
