Archicebus

Abstract: Obtaining accurate estimations of the body mass of fossil primates has always been a subject of interest in paleoanthropology because mass is an important determinant for so many other aspects of biology, ecology, and life history. This paper focuses on the issues involved in attempting to reconstruct the mass of two early Eocene haplorhine primates, Teilhardina and Archicebus, which pose particular problems due to their small size and temporal and phylogenetic distance from extant primates. In addition to a ranking of variables from more to less useful, the effect of using models of varying taxonomic and size compositions is examined. Phylogenetic correction is also applied to the primate database. Our results indicate that the choice of variable is more critical than the choice of model. The more reliable variables are the mediolateral breadth across the femoral condyles and the area of the calcaneocuboid facet of the calcaneus. These variables suggest a body mass of 39 g (range 33-46 g) for Archicebus and 48 g (range 44-56 g) for Teilhardina. The width of the distal femur is found to be the most consistent estimator across models of various composition and techniques. The effect of phylogenetic correction is small but the choice of branch length assumption affects point estimates for the fossils. The majority of variables and models predict the body mass of Archicebus and Teilhardina to be in the range of the smaller extant mouse lemurs, as expected.

Abstract: The Paleogene primate fossil record is reviewed following higher systematic categories. Among Strepsirhini, Adapiformes underwent Eocene radiations in North America (Notharctinae) and Europe (Cercamoniinae, Adapinae). Several occasional occurrences due to dispersals are found in North America, Europe, and Africa. Asia reveals a limited diversification (Sivaladapidae) and isolated occurrences indicating a central yet poorly understood role. In Africa the origin of living Lemuriformes is documented in the Late Eocene; odd stem lemuriforms occur earlier. The Eocene florescence of Omomyiformes is documented in North America (Anaptomorphinae, Omomyinae) and in Europe (Microchoeridae). Isolated occurrences, including the stem genus Teilhardina, are known in Asia. Two genera of Tarsiidae, known in the Middle Eocene of Asia, lead to a possible character-based definition of Haplorhini. The Asiatic Eosimiidae may belong in this group, and Archicebus may possibly lie on its stem. The Eocene South Asiatic Amphipithecidae are specialized hard-object feeders whose affinities remain enigmatic. Character-based Anthropoidea, or Simiiformes, are documented in the Late Eocene and Oligocene of Africa (Parapithecidae, Proteopithecidae, Oligopithecidae, Propliopithecidae). Toward the end of the Oligocene, the first African proconsuloids and the first South American platyrrhines appear. Anthropoidean origins are still a field of debate and discovery, with unconvincing Asiatic stem simians and a possible role for African Afrotarsiidae. The fossil record is extremely uneven, going from richly documented lineages in the Eocene of North America, to well-delineated radiations in the Eocene of North America and Europe and the Eocene–Oligocene of Africa, to more dispersed occurrences and enormous gaps during the early periods in Africa and Asia. The latters explain persisting controversies. Many aspects of primate evolution are documented over almost 20 million years, including locomotion, diet, vision and other sensory capacities, brain evolution, and one aspect of social structure via sexual dimorphism. The best records allow researchers to approach specific lineages, evolutionary modes, and analysis of faunistic changes. 1138 M. Godinot