Elsevier

Gondwana Research

Volume 99, November 2021, Pages 21-35
Gondwana Research

A fossil terrestrial fauna from Tobène (Senegal) provides a unique early Pliocene window in western Africa

https://doi.org/10.1016/j.gr.2021.06.013Get rights and content

Highlights

  • Description of ten mammalian taxa with high proportion of carnivorans from Senegal.

  • First report of an early Pliocene terrestrial vertebrate fauna from western Africa.

  • Global weathering events constrain the minimal age of the Tobène fauna.

  • Faunal similarities with eastern Africa suggest a wide biogeographical realm.

Abstract

Early Pliocene hominin evolutionary scenarios proposed to date mostly rely on paleontological investigations from eastern Africa. Filling major geographical gaps in the fossil record could potentially invalidate these scenarios and stimulate development of improved theories. Based on published literature, no Pliocene fossil of continental vertebrates have been discovered in Western Africa and the situation is only slightly better in central and northern Africa. Here, we expand the Pliocene vertebrate continental fossil record to western Africa with the description of the Tobène fauna, a new fossiliferous Neogene locality from Senegal. We describe a diversity of large mammals, including at least ten taxa based on fragmentary remains recovered from alluvial channel deposits. Estimation based on weathering events and biochronology suggests an early Pliocene age. Most of these mammalian taxa were widely distributed over the African continent during the early Pliocene. Possible faunal correlations with eastern African localities call for continent-wide paleontological investigations.***************

Introduction

Hypotheses on early hominins temporal and spatial distribution across Africa were formulated on the basis of geographically restricted paleontological data. The informal concept of “cradle of humankind” – repeatedly recognized in different regions– perfectly exemplifies how grey areas in the fossil record can bias our understanding of early human history. Although Pliocene localities are common and intensively surveyed in eastern and southern Africa (Werdelin, 2010), this time period remains poorly documented in the rest of the continent, notably in northern and central Africa (Arambourg, 1979, Brunet et al., 1995, Brunet et al., 1998, Brunet et al., 2000, Werdelin, 2010, Zouhri et al., 2017). Researchers however acknowledge important biases in the fossil record when proposing new biogeographic hypotheses or conceptual models (e.g. Joordens et al., 2019), especially the lack of vertebrate remains in western Africa for this time period. Outcrops exploitable for fossil discoveries are rare in this area, mostly due to Cenozoic lateritic weathering, vegetation, and the widespread Quaternary sand cover along the southern fringe of the Sahara (e.g., Michel, 1973, Beauvais et al., 2008).

Recent prospections undertaken as part of the PaleoSen project between 2012 and 2015 uncovered several vertebrate fossils in the Taïba Ndiaye quarry, Senegal (Fig. 1). Most of these remains were found in limestone deposits embedded in the Lutetian-Bartonian phosphate ore formation, and belonged to marine vertebrates (Hautier et al., 2012, Hautier et al., 2014, Vautrin et al., 2019). Remains have also been excavated from the overlying continental deposits intercalated between the Eocene phosphate ore and the Quaternary sand cover in the Tobène pit of the Taïba Ndiaye quarry (Hautier et al., 2014).

This paper provides a description of the Tobène site, which hosts the only known Pliocene fauna from Senegal and well-beyond classical African Pliocene faunas, being 2,400 km distant from the nearest known Pliocene fossil site of Lissasfa, Morocco (Raynal et al., 1999) and Kossom Bougoudi and Kollé, Chad (Brunet et al. 1998, 2000) (Fig. 1). The Tobène locality, although poor in fossils relative to other Pliocene localities, is key to documenting the distribution of Pliocene ecosystems in Africa. Its age estimation was based on the combined study of biochronological markers and lateritic weathering events documented regionally and dated using geochronology (Beauvais et al., 2008). The taxonomic richness of the locality and the abundance of carnivorans is encouraging for future discoveries.

Section snippets

Geological context

The PaleoSen project is a collaborative framework between Senegalese and French paleontologists from the University Cheikh Anta Diop of Dakar and the Institut des Sciences de l’Evolution of Montpellier. In addition to numerous field expeditions led in Senegalese Paleogene outcrops, three fieldtrips (2012, 2013, and 2015) focused on prospecting the upper part of the Tobène pit in the Taïba Ndiaye quarry, i.e., in strata overlying the exploited phosphate ore (Hautier et al., 2014).

During ore

Description of cf. Osteolaemus

Class Reptilia Laurenti, 1768

Order Crocodylia Gmelin, 1789

Family Crocodylidae Cuvier, 1807

cf. Osteolaemus

Age of the fossiliferous conglomerate

The age of the Tobène fossiliferous locality is first discussed from the perspective of paleoweathering chronology, then from the perspective of biochronology.

Cenozoic climate changes over Sahelian western Africa led to punctuated erosion/weathering history of its landscape. During the Neogene, three main pediment systems (erosion and transportation land surfaces) formed under a dominantly semi-arid climate (Chardon et al., 2018). Each of these surfaces was weathered/duricrusted under

Conclusions

Most Sahelian sediments of putative late Cenozoic age are overlain by Quaternary sands that preclude surveys for fossil remains. In Senegal, Pliocene continental sediments are only exposed in mining quarries. The Tobène pit fauna shows that the latest iron duricrusts formed in West Africa in the late Pliocene may cap (and protect) continental strata that have the potential to fill a major gap in our understanding of African fossil faunas. Furthermore, the conspicuous and widespread occurrence

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

We would like to thank Mr El Hadji Mansour Sambe and Mr Ibrahima Gaye, authorities of the Industries Chimiques du Sénégal of the quarry of Taïba Ndiaye, for their logistic help and authorization. We also thank Faye Lassy of the ICS for his help in the field. The work benefited from the support of the Geology Department of the University Cheikh Anta Diop (Prof. E. Sow and Dr. Faaye Cisse S.). We are indebted to colleagues who allowed us accessing their collection: dir. Desalegn Abebaw, and T.

Funding

This work was supported by the CNRS PICS Grant; the International Exchange Scheme of the Royal Society; the National Geographic Society’s Global Exploration Fund (Northern Europe); the Sidney Sussex College (Cambridge, UK) and the IRD.

REFERENCES (110)

  • C.C. Gilbert et al.

    Partial skeleton of Theropithecus brumpti (Primates, Cercopithecidae) from the Chemeron Formation of the Tugen Hills

    Kenya. J. Hum. Evol.

    (2011)
  • Y. Haile-Selassie et al.

    Comparative description and taxonomy of new hominin juvenile mandibles from the Pliocene of Woranso-Mille (Central Afar, Ethiopia)

    J. Hum. Evol.

    (2019)
  • F.J. Hilgen et al.

    The Neogene period

  • J.C.A. Joordens et al.

    Relevance of the eastern African coastal forest for early hominin biogeography

    J. Hum. Evol.

    (2019)
  • M.E. Lewis

    The femur of extinct bunodont otters in Africa (Carnivora, Mustelidae, Lutrinae)

    C. R. Palevol

    (2008)
  • F.K. Manthi et al.

    Diets of mammalian fossil fauna from Kanapoi, northwestern Kenya

    J. Hum. Evol.

    (2020)
  • A. Novello et al.

    Phytoliths indicate significant arboreal cover at Sahelanthropus type locality TM266 in northern Chad and a decrease in later sites

    J. Hum. Evol.

    (2017)
  • M. Pickford et al.

    Late Miocene hominoid from Niger

    C. R. Palevol

    (2009)
  • J.-P. Raynal et al.

    Contribution du site paléontologique de Lissasfa (Casablanca, Maroc) à une nouvelle interprétation du Mio-Pliocène de la Meseta. C. R. Acad. Sci

    Paris

    (1999)
  • K.E. Reed

    Paleoecological patterns at the Hadar hominin site, Afar Regional State

    Ethiopia. J. Hum. Evol.

    (2008)
  • D.L. Roberts et al.

    Regional and global context of the Late Cenozoic Langebaanweg (LBW) palaeontological site: West Coast of South Africa

    Earth-Sci. Rev.

    (2011)
  • M. Sahnouni et al.

    Ecological background to Plio-Pleistocene hominin occupation in North Africa: the vertebrate faunas from Ain Boucherit, Ain Hanech and El-Kherba, and paleosol stable-carbon-isotope studies from El-Kherba

    Algeria. Quat. Sci. Rev.

    (2011)
  • B. Simon et al.

    Deformation and sedimentary evolution of the Lake Albert Rift (Uganda, East African Rift System)

    Mar. Petrol. Geol.

    (2017)
  • M. Sotnikova et al.

    Carnivora of the Tamanian faunal unit (the Azov Sea area)

    Quatern. Int.

    (2009)
  • M. Antón et al.

    First known complete skulls of the scimitar-toothed cat Machairodus aphanistus (Felidae, Carnivora) from the Spanish Late Miocene site of Batallones-1

    J. Vert. Paleontol.

    (2004)
  • M.T. Antunes

    Presença de Osteolaemus tetraspis nas lagoas asfálticas de Sassa-Zau (Maiombe)

  • R. Aoki

    Fossil crocodilians from the late Tertiary strata in the Sinda Basin, eastern Zaire

    Afr. Study Monogr. : Supplementary issue

    (1992)
  • C. Arambourg

    Vertébrés villafranchiens d’Afrique du Nord

    (1979)
  • C. Basu et al.

    The extinct, giant giraffid Sivatherium giganteum : skeletal reconstruction and body mass estimation

    Biol. Lett.

    (2016)
  • Beaumont, G., de, 1975. Recherches sur les félidés (mammifères, carnivores) du Pliocène inférieur des sables à...
  • A. Beauvais et al.

    Modes, tempo, and spatial variability of Cenozoic cratonic denudation: the West African example

    Geochem. Geophys. Geosyst.

    (2013)
  • A. Beauvais et al.

    Chemical and physical erosion rhythms of the West African Cenozoic morphogenesis: the 39Ar- 40Ar dating of supergene K-Mn oxides

    J. Geophys. Res.

    (2008)
  • F. Bibi

    Mio-Pliocene faunal exchanges and African biogeography: the record of fossil bovids

    PLoS ONE

    (2011)
  • F. Bibi et al.

    A new African fossil caprin and a combined molecular and morphological bayesian phylogenetic analysis of Caprini (Mammalia: Bovidae)

    J. Evolution. Biol.

    (2012)
  • Brochu, C. A., 2020. Pliocene crocodiles from Kanapoi, Turkana Basin, Kenya. J. Hum. Evol. 140, 102410. DOI:...
  • M. Brunet et al.

    The first australopithecine 2 500 kilometres west of the Rift Valley (Chad)

    Nature

    (1995)
  • M. Brunet et al.

    Chad : discovery of a vertebrate fauna close to the Mio-Pliocene boundary

    J. Vert. Paleontol.

    (2000)
  • M. Bukhsianidze et al.

    Capra dalii nov. sp. (Caprinae, Bovidae, Mammalia) at the limit of Plio-Pleistocene from Dmanisi (Georgia)

    Cour. Forsch. Senck.

    (2006)
  • T.E. Cerling et al.

    Dietary changes of large herbivores in the Turkana Basin, Kenya from 4 to 1 Ma

    Proc. Natl. Acad. Sci. USA

    (2015)
  • P. Christiansen

    Phylogeny of the sabertoothed felids (Carnivora: Felidae: Machairodontinae)

    Cladistics

    (2013)
  • P. Christiansen et al.

    Osteology and ecology of Megantereon cultridens (Mammalia; Felidae; Machairodontinae), a sabrecat from the late Pliocene–early Pleistocene of Senéze

    France. Zool. J. Linn. Soc. London

    (2007)
  • H.B.S. Cooke et al.

    Nyanzachoerus (Mammalia: Suidae: Tetraconodontinae) from Langebaanweg

    South Africa. Durban Mus. Nov.

    (1992)
  • Y. Coppens

    Une nouvelle espèce de suidé du Villafranchien de Tunisie, Nyanzachoerus jaegeri nov. sp

    C. R. Acad. Sci. Paris

    (1971)
  • Y. Coppens

    Les vertébrés villafranchiens de Tunisie : gisements nouveaux, signification

    C. R. Acad. Sci. Paris

    (1971)
  • Y. Coppens et al.

    Découverte d’un gisement de vertébrés fossiles avec industrie acheuléenne près de Zouérate en Mauritanie

  • E. Crégut-Bonnoure et al.

    Perspectives morphométriques et phylogéniques du genre Capra au Pléistocène (Mammalia, Artiodactyla, Caprinae)

    Quaternaire

    (2018)
  • M. Delfino

    New remains of Crocodylus checchiai Maccagno 1947 (Crocodylia, Crocodylidae) from the Late Miocene of As Sahabi

    Libya. Garyounis Sci. Bull.

    (2008)
  • M.J. Eaton

    Dwarf Crocodile Ostaeolaemus tetraspis

  • A.W. Gentry

    Fossil Bovidae (Mammalia) from Langebaanweg, South Africa

    Ann. TransvaalMus.

    (1980)
  • A.W. Gentry

    A new bovine (Bovidae, Artiodactyla) from the Hadar formation

    Ethiopia. Trans. R. Soc. South Africa

    (2006)
  • Cited by (4)

    • Evolution and Fossil Record of African Proboscidea

      2023, Evolution and Fossil Record of African Proboscidea
    View full text