Dietary niches of terrestrial cercopithecines from the Plio-Pleistocene Shungura Formation, Ethiopia: evidence from Dental Microwear Texture Analysis

Scientific Reports, Sep 2018

This study aims to explore the feeding ecology of two terrestrial papionins, Papio and Theropithecus from the Shungura Formation in Ethiopia, the most complete stratigraphic and paleontological record of the African Plio-Pleistocene. Two aspects were evaluated using Dental Microwear Texture Analysis: differences in diet between the extinct genera and their extant relatives, and any potential dietary fluctuations over time. Amongst more than 2,500 cercopithecid dental remains, 154 Theropithecus molars and 60 Papio molars were considered. Thirty-nine extant wild baboons and 20 wild geladas were also considered. The results show that diets of extinct monkeys from Member G already differed between genera as it is the case for their extant representatives. The shearing facets on the Theropithecus molars display significant variations in microwear textures, suggesting several dietary shifts over time. Two events point to higher intakes of herbaceous monocots (tougher than dicots foliages), at about 2.91 Ma (between members B and C) and at 2.32 Ma (between members E and F). These two events are separated by an inverse trend at about 2.53 Ma (between members C and D). Some of these variations, such as between members E and F are supported by the enamel carbon isotopic composition of herbivorous mammals and with paleovegetation evidence.

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Dietary niches of terrestrial cercopithecines from the Plio-Pleistocene Shungura Formation, Ethiopia: evidence from Dental Microwear Texture Analysis

SCIENtIfIC REPORTS | Dietary niches of terrestrial cercopithecines from the Plio- Pleistocene Shungura Formation, Ethiopia: evidence from Dental Microwear Texture Analysis Florian Martin Jean-Renaud Boisserie 0 3 0 Laboratory Paleontology Evolution Paleoecosystems Paleoprimatology (PALEVOPRIM) - UMR CNRS-INEE/ University of Poitiers , 86073, POITIERS CEDEX 9 , France 1 School of Geology, Aristotle University of Thessaloniki , 52124, THESSALONIKI , Greece 2 De la Pre?histoire l'Actuel: Culture, Environnement et Anthropologie (PACEA) - UMR 5199 CNRS/Universite? de Bordeaux/Ministe?re de la Culture et de la Communication , 33615, PESSAC CEDEX , France 3 Centre Franc?ais des Etudes Ethiopiennes (CFEE) - USR 3137 CNRS/Ministe?re de l'Europe et des Affaires OPEN Published: xx xx xxxx This study aims to explore the feeding ecology of two terrestrial papionins, Papio and Theropithecus from the Shungura Formation in Ethiopia, the most complete stratigraphic and paleontological record of the African Plio-Pleistocene. Two aspects were evaluated using Dental Microwear Texture Analysis: differences in diet between the extinct genera and their extant relatives, and any potential dietary fluctuations over time. Amongst more than 2,500 cercopithecid dental remains, 154 Theropithecus molars and 60 Papio molars were considered. Thirty-nine extant wild baboons and 20 wild geladas were also considered. The results show that diets of extinct monkeys from Member G already differed between genera as it is the case for their extant representatives. The shearing facets on the Theropithecus molars display significant variations in microwear textures, suggesting several dietary shifts over time. Two events point to higher intakes of herbaceous monocots (tougher than dicots foliages), at about 2.91 Ma (between members B and C) and at 2.32 Ma (between members E and F). These two events are separated by an inverse trend at about 2.53 Ma (between members C and D). Some of these variations, such as between members E and F are supported by the enamel carbon isotopic composition of herbivorous mammals and with paleovegetation evidence. - Papio and Theropithecus are terrestrial cercopithecids whose extinct relatives were more diverse and widespread. For example, the modern gelada (Theropithecus gelada) is a refugee species in the Ethiopian High Plateau, with a restricted geographical range and likely a reduced set of habitats compared to its extinct relatives (Fig.?1). The present work aims to investigate the ecological segregation between these two primate genera found in eastern African Plio-Pleistocene sites. The second goal is to track changes in the feeding habits of these cercopithecids that reflect variations in food resources over time, in the context of environmental changes during the Plio-Pleistocene at a regional scale. To do so, dental microwear textures of specimens of Papio and Theropithecus from the Shungura Formation were analyzed. Shungura is a geological formation situated within the Lower Omo Valley, on the northern part of the Turkana Basin in southwestern Ethiopia (Fig.?1). Its sedimentary deposits have yielded major Plio-Pleistocene paleontological and archeological records, including numerous hominin and lithic remains. It is subdivided into 12 geological members, from the lowermost to the uppermost: Basal, A to H, and J to L. The main volcanic tuffs of the formation, forming the base of each member, allow for long distance stratigraphic correlations. These and other ash layers have been dated by radiochronological methods, including 40K/40Ar and 40Ar/39Ar, and by magnetostratigraphy. These methods and extrapolations from their results are Addis Ababa SNNPR Shungura Lake Turkana Guassa Indetu ETHIOPIA 0 100 km indicative of a time interval of 3.6 Ma to 1.05 Ma for the deposition of the formation. This in turn led to a particularly accurate chronostratigraphic framework for testing evolutionary hypotheses. Unlike all other African Plio-Pleistocene sites, this formation displays a good chronological continuity of its sedimentary deposits, notably between 3 Ma and 2 Ma, documenting a critical period in hominin evolution marked by the transition between Australopithecus and Homo and by the emergence of Paranthropus. The inter-specific and temporal variations in the dental microwear textures of these terrestrial monkeys were compared with enamel stable carbon isotopic data and paleovegetation evidence. This provides insights into the available vegetation in the cercopithecid habitats along the ancestral Omo River and therefore allows for identifying environmental trends. Most primate remains found in the Shungura Formation belong to Papio and Theropithecus. The latter taxon has a unique dietary specialization among extant primates: it forages predominantly on the herbaceous layer and mostly on monocotyledons. Today, Papio is represented by several species throughout Africa. Up to six species have been recognized (...truncated)


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Florian Martin, Chris-Alexander Plastiras, Gildas Merceron, Antoine Souron, Jean-Renaud Boisserie. Dietary niches of terrestrial cercopithecines from the Plio-Pleistocene Shungura Formation, Ethiopia: evidence from Dental Microwear Texture Analysis, Scientific Reports, 2018, Issue: 8, DOI: 10.1038/s41598-018-32092-z