palaeoantology

4

Dietary Specialization during the Evolution of Western Eurasian Hominoids and the Extinction of European Great Apes

  • by Daniel DeMiguel, David M. Alba and Salvador Moyà-Solà

“Given the central adaptive role of diet, paleodietary inference is essential for understanding the relationship between evolutionary and paleoenvironmental change. Here we rely on dental microwear analysis to investigate the role of dietary specialization in the diversification and extinction of Miocene hominoids from Western Eurasian between 14 and 7 Ma. New microwear results for five extinct taxa are analyzed together with previous data for other Western Eurasian genera. Except Pierolapithecus (that resembles hard-object feeders) and Oreopithecus (a soft-frugivore probably foraging opportunistically on other foods), most of the extinct taxa lack clear extant dietary analogues. They display some degree of sclerocarpy, which is most clearly expressed in Griphopithecus and Ouranopithecus (adapted to more open and arid environments), whereas Anoiapithecus, Dryopithecus and, especially, Hispanopithecus species apparently relied more strongly on soft-frugivory. Thus, contrasting with the prevailing sclerocarpic condition at the beginning of the Eurasian hominoid radiation, soft- and mixed-frugivory coexisted with hard-object feeding in the Late Miocene. Therefore, despite a climatic trend towards cooling and increased seasonality, a progressive dietary diversification would have occurred (probably due to competitive exclusion and increased environmental heterogeneity), although strict folivory did not evolve. Overall, our analyses support the view that the same dietary specializations that enabled Western Eurasian hominoids to face progressive climatic deterioration were the main factor ultimately leading to their extinction when more drastic paleoenvironmental changes took place” (read more/open access).

(Open access sourcePLoS ONE 9(5): e97442, 2014)

A leopard ate a chimpanzee: First evidence from East Africa

“Primates may have suffered predation pressures throughout their evolutionary history. Hominoids have been sympatric with arge carnivores since the early Miocene in Africa (Werdelin and Peigné, 2010), and it is thought that predation pressure by large carnivores has played a significant role in their evolution (Hart and Sussman, 2005). For example, carnivore predation on Proconsul has been inferred from site R114 (‘Pot-hole’) on Rusinga Island, Kenya, where the partial skeleton of Panthera heseloni KNM-RU 2036 was recovered (Walker and Shipman, 2005).

In addition to fossil evidence, data on predation on living primates is also important for reconstructing the predation pressure on our human ancestors. Among potential nonhuman predators of living African apes, leopards (Panthera pardus) and lions (Panthera leo) have been known to actually prey upon apes. There has been only one report of lion predation on apes (Tsukahara, 1993). Lions are usually allopatric with apes because they are absent from tropical rainforests (Nowell and Jackson, 1996) where the majority of apes live. On the other hand, because leopards occur in most parts of sub-Saharan Africa (ibid.), they may be more likely than lions to prey upon apes. There has been limited information on leopard predation on apes, and all data have come from West and Central Africa (Table 1). Moreover, despite long-term research on chimpanzees (Pan troglodytes schweinfurthii) at several sites in East Africa, no instances of leopard predation have been reported. This is probably because of the recent extirpation of leopards from most of the research sites. According to personal communications from experienced field researchers, there has been no evidence of the presence of leopards for a decade or more at the research sites of Gombe (M.L. Wilson) in Tanzania, and Kalinzu (C. Hashimoto), Kibale (T. Struhsaker, J.C. Mitani, and D.R. Mills) and Budongo (N.E. Newton-Fisher) in Uganda. The only exception is Mahale in Tanzania where leopards have lived sympatrically with chimpanzees, without evidence of predation by the former on the latter (Nishida, 2012). There have been several reports of encounters between leopards and chimpanzees from Tanzania including Mahale (reviewed in Pierce, 2009). Responses of chimpanzees to leopards varied from emitting loud, fearful calls, vigilance, and acting in a threatening manner (e.g., Pierce, 2009); stalking a leopard that had called in the distance (Personal communication, J.C. Mitani); to surrounding a den and killing a cub (Hiraiwa Hasegawa et al., 1986)” (read more/not open access).

(Source: Journal of Human Evolution, in press 2013)