Cranial and endocranial morphology of a new species of giant civet (Carnivora, Viverridae) from the early Pliocene of Langebaanweg ‘E’ Quarry, South Africa

Abstract

We present an extensive cranial sample of an extinct large viverrid from the Pliocene Varswater Formation at Langebaanweg ‘E’ Quarry (South Africa, 5.2 Ma), comprising a complete skull, multiple dentaries, and isolated dentition. The intermediate temporal position of Langebaanweg relative to Toros Menalla (Chad, 7 Ma) and Laetoli1 (Tanzania, 3.8–3.5 Ma), the type localities of Sahelictis korei and ‘Viverra’ leakeyi respectively, influenced the historical attribution of the known material of this viverrid as belonging to either taxon. The re-evaluation of the classical material from this locality, in conjunction with these new specimens, permits its assignment to a new species, named Civettictis vulpidens. It emerges as the most complete sample of a large viverrid in the fossil record. Civettictis vulpidens sp. nov , exhibits some intraspecific variable traits, particularly regarding the degree of development of the P4 parastyle, and the cuspids position in the m2. It differs from C. leakeyi in the upper canine cross sections, which is circular and without smaller cristae on the distal face, in the absence of P3 mesial and distal accessory cusp, and in a more primitive morphology of the carnassials, comprising a relatively longer P4 metastyle, a reduced to absent P4 paraconule, a reduced m1 metaconid, and a shorter and slenderer m1 talonid, with no crista obliqua. It also differs from S. korei in a relatively shorter P4 mestastyle, a more bunodont M1, a slenderer P3, and a better developed m1 talonid with an entoconid. Our cladistic analysis demonstrates a sister-group relationship of C. vulpidens sp. nov., with a clade composed of C. leakeyi and the extant Civettictis civetta (African civet), which is morphologically distinct from the extant Viverra zibetha (large Indian civet). We also obtained a relationship of successive sister groups between, Civettictis Megaviverra, and Sahelictis. The endocast of C. vulpidens sp. nov., has the same superficial brain morphology in C. civetta, with the addition of an ectosylvian sulcus on the left hemisphere, a long entolateral sulcus on each hemisphere and an anteroposteriorly oriented sulcus medial to the right coronal sulcus. We propose the term “entocoronal” for this sulcus. The endocranial skull surface is damaged where a left entocoronal sulcus might have been reproduced. The common presence of a straight posterior cerebellar vermis distinguishes both C. civetta and C vulpidens sp. nov. from V. zibetha, Viverra megaspila Viverra tangalunga and Viverricula indica. Preliminary ecomorphological comparison show that this giant civet is less specialised and larger than the modern C. civetta and may have played a mesocarnivore role in the Langebaanweg fauna, like the smaller-sized canine Eucyon khoikhoi from the same locality.