A new species of Nyanzachoerus (Cetartiodactyla: Suidae) from the late Miocene Toros-Ménalla, Chad, central Africa

PLoS One. 2014 Aug 27;9(8):e103221. doi: 10.1371/journal.pone.0103221. eCollection 2014.

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.

Publication types

  • Historical Article
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Bicuspid / anatomy & histology
  • Bicuspid / physiology
  • Chad
  • Female
  • Fossils / anatomy & histology*
  • Fossils / history
  • Genetic Speciation
  • History, Ancient
  • Male
  • Mandible / anatomy & histology
  • Mandible / physiology
  • Molar / anatomy & histology
  • Molar / physiology
  • Paleontology
  • Phylogeny*
  • Phylogeography
  • Swine / anatomy & histology*
  • Swine / classification*
  • Swine / physiology

Grant support

The funders of our work are: Agence Nationale de la Recherche (latest funding: ANR-09-BLAN-0238, PI: M. Brunet); French Ministère des Affaires Étrangères (DCUR/RECH in Paris, French Embassy in Chad, FSP n° 2005-54 of the Franco-Chadian cooperation); Région Poitou-Charentes ; Revealing Hominid Origins Initiative (U.S. National Science Foundation Award #BCS-0321893); European Union Synthesis program (grant GB-TAF 886 to AS for work at NHM). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.