We have tested for the first time a multiproxy analysis to reconstruct the diet of Macaca cf. sylvanus from North Africa. The multiproxy approach include isotopic signal and both occlusal and buccal microwear.
An interdisciplinary Spanish–Moroccan project started in 2006 as an international cooperation between the Université Mohamed Premier Oujda (UMP, Eastern Morocco) and the Catalan Institute for Human Palaeoecology and Social Evolution from Tarragona (IPHES-CERCA, Catalonia, Spain). The aim of this cooperation is to establish the geochronological and archeo-paleontological context of the Aïn Beni Mathar/Guefaït fluvio-lacustrine basin, in the northern part of the High Plateaus (Jerada Province, Eastern Morocco).
One of the systematic surveys in the region revealed the fossiliferous level of Guefaït-4. This horizon yielded a rich and diverse faunal assemblage of vertebrates, which was systematically excavated at the GFT-4.2 site (reptiles, amphibians, and both small and large mammals), including the macaque fossil remains analyzed in this work. Fossil remains were concentrated in a palustrine level constituted of clay and marls, at the base of Unit 2, within the Dhar Iroumyane stratigraphic section.
Material and methods
Macaca genus belongs to Cercopithecidae (Old World monkeys), Cercopithecinae, Papionini. The presence of Macaca in North Africa is well known from the Late Miocene to the Late Pleistocene. The diet of fossil Macaca, however, has been poorly described in the literature. In this study, we investigated the feeding habits of Macaca cf. sylvanus (n = 4) from the Plio-Pleistocene site Guefaït-4.2 in eastern Morocco through multiproxy analysis combining analyses of stable carbon and oxygen isotopes from tooth enamel, buccal microtexture, and low-magnification occlusal dental microwear. For both microwear analyses, we compared the macaques with a new reference collection of extant members of Cercopithecoidea.
Results and conclusions
Our occlusal microwear results show for the fossil macaque a pattern similar to the extant Cercocebus atys and Lophocebus albigena, African forest-dwelling species that are characterized by a durophagous diet based mainly on hard fruit and seed intake. Buccal microtexture results also suggest the consumption of some grasses and the exploitation of more open habitats, similar to that observed in Theropithecus gelada.
The δ13C of M. cf. sylvanus indicates a C3 based-diet without the presence of C4 plants typical of the savanna grassland in eastern Africa during this period. Furthermore, the high δ18O values of M. cf. sylvanus, compared with the contemporary ungulates recovered from Guefaït-4.2, could be associated with the consumption of a different resource by the primate such as leaves or fresh fruits from the upper part of trees. The complementarity of these methods allows therefore, for a dietary reconstruction covering a large part of the individual’s life.
Frontiers in Ecology and Evolution, February 2023