The Evolution of African Mammals II: The Essential Sequel

Abstract

If you frequently find yourself reaching for a ba6ered copy of Maglio and Cooke’s The Evolu*on of African Mammals, you have either already ordered Cenozoic Mammals of Africa (Werdelin and Sanders, eds., University of California Press, 2010, 986 pp.), or you have been in the field conKnuously and should order it immediately. Like Evolu*on of African Mammals, this is a synopKc treatment of the Cenozoic record of Africa, organized along the same lines and expanded to cover the vast wealth of material recovered since the late 1970s. For much of the early Cenozoic, Africa, like South America and Australia, was an isolated island conKnent. Beginning in the Oligocene, Africa experienced what seems to have been a gradual, one-­‐way infiltraKon of mammals from Eurasia, ramping up to higher levels in the Miocene as Tethys closed (Gheerbrant and Rage, 2006). Unlike the other Gondwanan conKnents, Africa had a core stock that included laurasiatherians and the early Cenozoic history documents the flowering of a highly endemic fauna of paenungulates, hyaenodonKd creodonts, macroscelideans and embrithopods, and early invaders such as anthracotheres. Through the Oligocene and Miocene, some of these were replaced by invading arKodactyls and perissodactyls (hyracoids, embrithopods), while others (primates, proboscideans) flourished. Though not explicitly addressed by any one chapter, this biogeographic history echoes through the taxonomic chapters: the endemic, Paleogene taxa are to be found primarily within the secKons on Afrotheria and Euarchontoglires, and the later immigrants belong within the Laurasiatheria. There are three secKons: a set of five introductory papers; a series of forty taxonomic accounts covering all of the mammalian taxa known, organized by modern clades (Metatheria, Afrotheria, Euarchontoglires and Laurasiatheria) and ranging in length from two pages to ninety pages; and three papers termed ‘Broader PerspecKves’, which cover a grab bag of topics. The introductory chapters provide a necessary background covering the tectonic and geomorphologic history of Africa (Partridge), summaries of geochronology and the biostraKgraphic framework (Seiffert for the Paleogene, and Werdelin for the Neogene), the complex vegetaKon history (Jacobs et al.) , and regional and global climate (Feakins and Demenocal). The Broader PerspecKves summarize the evidence for the Afrotheria hypothesis (Seiffert et al), the pa6erns of conKnental species richness over Kme (Andrews and O’Brien) and a review of the use of stable isotopes on Neogene mammal faunas from Africa (Cerling et al.). The taxonomic accounts (the bulk of the book) reflect the tremendous increase in knowledge of Cenozoic African mammals over the last thirty years. Much of this increase results from work on eastern and southern African Neogene hominid sites. The result of this intensive sampling is somewhat lopsided, as Werdelin (Chapter 3) points out — western and central Africa are almost completely unknown in the Neogene, while eastern and southern Africa are as well sampled as Europe and North America for some intervals and patchier for others. Although less voluminous, there are several chapters devoted, in essence, to the Paleogene record. Material from new late Paleocene sites in Morocco, and Eocene and Oligocene sites in Algeria, Tunisia, Mali, Senegal, Libya, Oman, Angola Tanzania, Ethiopia and Eritrea and reanalysis of the classic Fayum localiKes have greatly expanded our knowledge of endemic African lineages and the early Cenozoic fauna of Africa. Among the afrotherians, the fossil record of proboscideans and hyracoids has been dramaKcally expanded. The earliest history of proboscideans has been revealed in these new sites, completely revising our understanding of early proboscidean evoluKon. Sanders et al. thoroughly review the state of proboscidean systemaKcs and taxonomy, the geographic and straKgraphic distribuKon of new material, and new informaKon on the evoluKon of ontogeny