Early History and Biogeography of South America’s Extinct Land Mammals

Szalatavus attricuspis, an Early Platyrrhine Primate

“…Their resemblances to omomyids [1,7,8,22] confirm this status and further imply that these features are also primitive for an thropoids. For example, the hypocones on upper first and second molars are relatively small in Szalatavus and Branisella, and hypoconulids are absent on lower molars, as in omomyids.…”

A new fossil cebine from hispaniola

“…Essentially this view was espoused in 1980 by Wood, who further specified that the geographical area of New World hystricognath differentiation was Middle America, and that the Greater and Lesser Antilles acted as a lengthy tesselated pathway for southbound rodent colonists. McKenna (1980) indicates a slight preference for a similar routing for early platyrrhines, largely because he considers it more likely than not that New World monkeys arose in North America (see also Gingerich and Schoeninger, 1977). These scenarios, like others considered above, lack confirmatory evidence, and have other defects besides.…”

“…A more precise analysis of immediate origins is, however, greatly hindered by evidentiary problems. Edentates underwent their greatest evolution, if not their first differentiation, in South America (Simpson, 1978;McKenna, 1980), and the earliest known representatives of the platyrrhines and hystricognaths are also South American (E. Oligocene, Argentina and Bolivia; Hofstetter, 1969;Wood and Patterson, 1959). It has long been thought satisfactory to conclude, therefore, that the progenitors of the Antillean sloths, primates, and rodents came from South America.…”

Afrotherian affinities for endemic South American “ungulates”

“…Moreover, most alternative hypotheses about the major relationships of pyrotheres and xenungulates ally both clades to mammalian groups currently included within Afrotheria (e.g. Ameghino, 1902Ameghino, , 1906Loomis, 1914;Simpson, 1934Simpson, , 1945McKenna, 1975McKenna, , 1980Cifelli, 1983Cifelli, , 1993Shockey and Anaya Daza, 2004). Additionally, pyrotherians shows similarities in cranial morphology to some afrotherians, including their tympanic bullae composed of both ectotympanic and entotympanic components (Prothero, 1993).…”