Abstract
During the latest Miocene and the early Pliocene, tetraconodontine suids were the most predominant large omnivorous mammals in Africa. Yet, new species were often identified on the grounds of limited evidence, a situation impacting their value for biochronological correlations as well as for environmental and biogeographical reconstructions. The description of the most abundant known collection of craniodental remains attributed to the tetraconodontine Nyanzachoerus helps to improve this situation. These specimens were collected in the upper Miocene deposits at Toros-Ménalla, northern Chad, central Africa, by the Mission Paléoanthropologique Franco-Tchadienne. We compared them with Nyanzachoerus from eastern and southern Africa, using extant species as a reference for patterns of morphological variation. Thanks to a large sample of observations, our work focused as much on craniomandibular morphology as on dental morphology and metrics (improved by an index scoring for the complexity of distal third molars and a detailed investigation of premolar-molar ratios). We recognized two taxa at Toros-Ménalla: Nyanzachoerus khinzir nov. sp. and Ny. cf. australis. We also revised the taxonomic status for other species, including: the restriction of Ny. syrticus to its holotype specimen from Sahabi (Libya), the resurrection of the nomen Ny. tulotos, and the synonymy of Ny. kuseralensis with Ny. waylandi. At Toros-Ménalla, Ny. khinzir was the only suid coexisting with the anthracotheriid Libycosaurus and the hominid Sahelanthropus, whereas Ny. cf. australis was associated with a different, probably younger faunal context. Nyanzachoerus. khinzir, which probably had a diversified diet, supports a latest Miocene biogeographical distinction between central Africa and eastern Africa.
Highlights
The Suidae have played an important role in building biochronological frames for late Neogene African sites [1,2,3,4,5]
It is not surprising that relatively recent contributions propose significantly different appraisals of the diversity and relationships within Nyanzachoerus [1,10,16,17,18], and that, to date, no formal, cladistic phylogenetic analysis of African tetraconodonts has been published. These large and abundant omnivores possibly occupied a significant niche in African Mio-Pliocene ecosystems, this current lack of systematic and phylogenetic consensus impedes their use in paleoenvironmental reconstructions, as well as casts doubts on their merits for building biochronological and paleobiogeographical hypotheses
In this work we propose to erect yet another species of Nyanzachoerus, based on fossils discovered at Toros-Menalla in the Djourab desert, northern Chad, by the Mission Paleoanthropologique Franco-Tchadienne
Summary
The Suidae have played an important role in building biochronological frames for late Neogene African sites [1,2,3,4,5]. It is not surprising that relatively recent contributions propose significantly different appraisals of the diversity and relationships within Nyanzachoerus [1,10,16,17,18], and that, to date, no formal, cladistic phylogenetic analysis of African tetraconodonts has been published. These large and abundant omnivores possibly occupied a significant niche in African Mio-Pliocene ecosystems, this current lack of systematic and phylogenetic consensus impedes their use in paleoenvironmental reconstructions, as well as casts doubts on their merits for building biochronological and paleobiogeographical hypotheses
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