Dinofelis sp.

Bonis, Louis de, Peigné, Stéphane, Mackaye, Hassane Taisso, Likius, Andossa, Vignaud, Patrick & Brunet, Michel, 2018, New sabre toothed Felidae (Carnivora, Mammalia) in the hominid-bearing sites of Toros Menalla (late Miocene, Chad), Geodiversitas 40 (3), pp. 67-86 : 82-84

Dinofelis sp.

REFERRED MATERIAL FROM TOROS MENALLA. — TM 74-01-06, left upper canine.

LOCALITY. — TM 79, Toros Menalla, Chad.

GEOLOGICAL AGE. — Late Miocene; c. 7 Ma.

DESCRIPTION

The tooth is almost complete except the top of the crown and is a little weathered, the enamel being flaked off in some parts ( Fig. 5B ). The crown, without any striation or crenulation, and the root, are compressed. The former displays an almost flat lingual surface and a slightly convex buccal one, with two, mesial and distal, cutting keels, the distal one being more trenchant, but both without any crenulation and striation. The proportions of (TM 74-01- 06) fit clearly the morphology of Dinofelis (mesiodistal and buccolingual maximum diameters are about 21.5 mm and 10.5 mm respectively, and the root height is 47 mm). The size is close to that of some specimens studied by Werdelin & Lewis (2001: table 1), but the material from Toros Menalla remains undiagnostic at species level.

DISCUSSION

The type species, Dinofelis cristata , comes from the late Miocene of China and India but the genus has been recovered in other places in Asia, in Europe until south of Spain, and it is probably the most common fossil felid in Africa. In the latter continent, the earliest records of the genus are known from Lothagam, Kenya, into layers dated from 7.5 to 4 Ma ( Werdelin & Lewis 2001; Werdelin & Peigné 2010). The genus was represented in Chad in the lower Pliocene of Kossom Bougoudi ( Bonis et al. 2008) by a piece of mandible and a piece of postcranium.

CONCLUSION

Tchadailurus adei n. gen., n. sp. displays some characters indicating machairodont affinities.The typical machairodonts have large, trenchant, sometimes dirk-like or scimitar-like upper canines with several others features linked to these canines, particularly large opening of the mouth, elongated glenoid process, reduced ascending ramus of the mandible, low mandibular condyle, large mastoid process, reduced lower canine and presence of a mandibular flange. Tchadailurus adei n. gen., n. sp. does not display all of these characters but is different from the extant and fossil Felinae in its quite compressed, relatively elongated and double keeled upper canines, which are a trade mark of the group although it is quite primitive when compared to other machairodonts, particularly those classified as Eumachairodontia ( Christiansen 2013). Tchadailurus adei n. gen., n. sp. displays also postcranial characters that bring it near the machairodont felids. The long coracoid process of the scapula and its small facet for the m. biceps brachii, the elongated medial process of the scapholunar, the short and robust Mc I, and its associated first phalanx are closer to the morphology of early machairodontines such as Promegantereon ogygia and Pseudaelurus quadridentatus than to that of pantherines ( Salesa et al. 2010b). Some Eumachairodontia, Amphimachairodus Kretzoi, 1929 and Lokotunjailurus , are known in the same geological level and, for some specimens, in the same localities as Tchadailurus n. gen. despite the large difference in evolutionary degree. If the machairodonts form a monophyletic group, the divergence of the primitive Tchadailurus adei n. gen., n. sp. could be quite old and its lineage did exist together with those of more specialized lineages without leaving any known traces in the fossil record during a long time in Africa and elsewhere.

The new studied materials allow completing the list of the Toros Menalla carnivorans with addition of two taxa. This Chadian assemblage now includes 8 species of felids from the size of a wild cat to that of a lion. Such a great richness of the fossil felid assemblage is extremely rare in the fossil record. In Eurasia, the richest fossiliferous localities comprise not more than four or five species of felids with, for example, the late Miocene sites of Batallones and Las Casiones ( Spain; Salesa et al. 2012a, b). In North America, no Miocene or Pliocene sites includes as many as felid species, and only the Pleistocene sites of Rancho La Brea counts up to eight felid species ( Stock & Harris 1992).

Obviously, this is in the particular context of the evolutionary history of the Felidae in Africa that Toros Menalla appears of paramount significance. The fossil record of the Felidae in Africa is heterogeneous, in both time and space ( Werdelin & Peigné 2010). The first half of the Neogene is very poorly documented, since only three genera of felids are known so far: the oldest record is Asilifelis Werdelin, 2011 from Kenya and dated to c. 18-20 Ma; it is followed by Diamantofelis Morales, Pickford, Soria &Fraile, 1998 and Namafelis Morales, Pickford, Fraile, Salesa & Soria, 2003 , both from Namibia and dated to c. 17-17.5 Ma.During the second half of the Neogene appeared the sabre-toothed cats in the early late Miocene, with the genus Machairodus Kaup, 1833 , first recorded in Bled Douarah, Tunisia, dated to c. 11-10 Ma ( Kurtén 1976). The family reached its greatest diversity during the late Miocene-early Pliocene, and especially during the middle Pliocene ( Werdelin & Lewis 2005), with Toros Menalla being one of the richest felid assemblages. Given that 90% of the fossil occurrences are situated in eastern and southern Africa ( Werdelin & Peigné 2010), the great diversity at Toros Menalla appears as quite exceptional. The few other very rich and comparable African felid assemblages are more recent than Toros Menalla, of Pliocene or Pleistocene in age, and they include six or seven species (Awash 7, Omo Usno, Woranso-Mille, and probably Langebaanweg; Werdelin & Peigné 2010); only the Laetolil Beds Upper Unit comprises as many taxa as Toros Menalla ( Werdelin & Peigné 2010; Werdelin et al. 2014).

The large number of carnivoran taxa, especially felids, in the fauna of Toros Menalla indicates certainly a favourable environment for this group of meat eater predators. Each of them was probably specialized in a type of prey depending on the size and habitat of these preys. We may imagine a diversified paleoenvironment with large plains occupied by big games which were elected prey for large felids or for the hunting hyaena Chasmaporthetes Hay, 1921 of which the long limb bones indicate a good runner ( Galiano & Frailey 1977). It is interesting to note that most of the Toros Menalla felids are machairodontines with different degrees of adaptation to that special way of life. Amphimachairodus kabir Peigné, Bonis, Likius, Mackaye, Vignaud & Brunet, 2005 , with its robust limbs ( Peigné et al. 2005a) was probably hunting by ambush in a forested area favoured by the presence of water. Lokotunjailurus fanonei Bonis, Peigné, Likius, Mackaye, Vignaud, Brunet, 2010 was smaller than Amphimachairodus and reached the size of a leopard. Based on the paleobiology of its close relative Lokotunjailurus emageritus Werdelin, 2003 , we infer that its relatively slender limbs “lacking extreme machairodont features” (except maybe by the robust first digit of the hand) certainly implies another way of preying upon medium-sized preys, as cf. Megantereon sp. and Dinofelis sp. probably did. The smallest species of the quintet, Tchadailurus adei n. gen., n. sp., would have hunt smaller animals. This great spectrum of carnivores, especially the large ones, indicates scenery with diverse habitats stocked by diverse herbivorous animals and leaving in mind the idea of a “paradise lost”.

Figures

FIG. 5. — Tchadailurus adei n. gen., n. sp., TM 112-00-99, from Toros Menalla. Metatarsals:right Mt II (A1) and Mt III (A2) in medial view; left Mt IV lateral view (A3) and subcomplete left Mt V in anterior view (A4). Dinofelis sp., TM 74-01- 06, from Toros Menalla: left upper canine in lateral (B1) and medial (B2) views. Scale bar: 10 mm.