Thalassictis sp.

Peigné, Stéphane, 2016, Carnivora, Geodiversitas 38 (2), pp. 197-224 : 214-217

cf. Thalassictis sp.

( Fig. 7 A-C; Table 8)

Ictitherium sp. – Malik & Nafiz 1933: 67, pl. 12, fig. 5. — Yalçınlar 1954: 140. — Ozansoy 1957: 33. Uncertain synonymy.

REFERRED MATERIAL FROM KÜÇÜKÇEKMECE. — Kadi Mezarligi Quarry unnumbered: right m1.

DESCRIPTION

The tooth ( Fig. 7 A-C) is complete except for the distal root. The paraconid and protoconid blades and the hypoconid tip show slight wear. The crown is low relative to its length. The paraconid blade is horizontal and similar in length to the protoconid one; the paraconid is lower than the protoconid. The metaconid is strongly reduced and lower than the paraconid; in occlusal view, it is slightly distal to the protoconid. The talonid is short (approximately 20% of m1 length; Table 8) and narrow, and displays only two cuspids of approximately equal height, although the hypoconid (a little worn here) probably was taller than the entoconid. The hypoconid crest is individualized and well distinct from the basal cingulid;mesially it starts between the metaconid and protoconid and becomes taller and cuspid-like distally.Mesially, the entoconid crest is very low and emerges in the middle of the metaconid distal side. It then runs obliquely and distally forms a small cuspid that is less individualized than the hypoconid. The distal margin of the talonid is nearly transversely oriented and no cuspid is present: the hypoconulid is clearly absent/vestigial in this tooth. A developed cingulid is present on the labial side of the crown and extends slightly on the lingual side of the paraconid.

COMPARISONS AND DISCUSSION

The Hyaenidae is one of the most diverse carnivoran families in Europe during the Miocene. This family experienced a diversification and geographic expansion during the late Miocene (Vallesian and early Turolian), before decreasing in diversity toward the end of the Turolian ( Werdelin& Solounias 1996). Morphologically (reduced metaconid and talonid, medium size), the carnassial from Küçükçekmece resembles that of species assigned to genera that are classified in the third ecomorph proposed by Werdelin & Solounias (1996), comprising Ictitherium Wagner, 1848 , Thalassictis , Hyaenotherium Semenov, 1989 and Hyaenictitherium Kretzoi, 1938 . Given their probable close relationships with the genera mentioned above and/or their similar m1 (see Werdelin 1988; Werdelin & Solounias 1991: fig. 38), I consider that Miohyaenotherium Semenov, 1989 and Palinhyaena Qiu, Huang & Guo, 1979 also belong to this ecomorph. The definition and specific content of these taxa have known many changes in the past ( Werdelin & Solounias 1991, 1996) and even recent authors do not always agree regarding their taxonomy (compare, e.g., Viranta & Werdelin 2003; Bonis 2004, 2005; Tseng & Wang 2007; Özkurt et al. 2015). It is beyond the scope of this paper to discuss this topic. In the context of this study, I have first considered the type species of each of these genera. Among them only Hyaenotherium wongii (Zdansky, 1924) (type species of Hyaenotherium ; = H. magnum Semenov, 1989), Palinhyaena reperta Qiu, Huang & Guo, 1979 (type species of Palinhyaena ), Hyaenictitherium hyaenoides (Zdansky, 1924) (type species of Hyaenictitherium ) and Ictitherium viverrinum Roth and Wagner, 1854 (type species of Ictitherium ) were included in Werdelin & Solounias (1991) cladistic analysis. The character analysis performed by these authors includes only two characters applicable to the tooth from Küçükçekmece: the number of talonid cuspids (character 7 in Werdelin & Solounias 1991: 51) and the presence/absence of the metaconid (character 8 in Werdelin & Solounias 1991: 51). The latter is not informative as the metaconid is present in all the species considered here and in the tooth from Küçükçekmece. The number of talonid cuspids is more diagnostic as the latter specimen has only two cuspids in the talonid, the hypoconid and the entoconid; the hypoconulid is absent/vestigial. All the type species listed above retain the primitive feature, i.e. three cuspids in the talonid of m1 (see also Semenov 2008: fig. 6; analysis of Tseng & Wang 2007: Appendix 2, character 6). However two genera were not included in the cladistic analysis of Werdelin & Solounias (1991): Miohyaenotherium and Thalassictis . These authors placed the species of these genera in a clade comprising Hyaenotherium , Hyaenictitherium and more derived genera (e.g., hunting hyaenas and bone-cracking taxa; Werdelin & Solounias 1991: fig. 38), considering, however, that the type and only species of Miohyaenotherium , M. bessarabicum Semenov, 1989 , is a possible synonym of Hyaenictitherium parvum (Khomenko, 1914) . In a recent analysis, Tseng & Wang (2007) considered the two latter species as synonyms of H. wongii . The close relationship of M. bessarabicum with Hyaenictitherium spp. and/ or Hyaenotherium wongii suggest that it is distinct from the species from Küçükçekmece. The genus Thalassictis includes the type species Thalassictis robusta Gervais, 1850 ex Nordmann MS and according to Werdelin & Solounias (1991) perhaps also: T. certa (Major, 1903) , T. sarmatica (Pavlow, 1908) , T. proava (Pilgrim, 1910) (= T. chinjiensis ( Pilgrim, 1932) ; see Werdelin & Solounias 1991: 35), T. montadai ( Villalta & Crusafont, 1943) and T. spelaea (Semenov, 1988) . Thalassictis sarmatica is based on a skull and not comparable to the material from Küçükçekmece. The m1 of the species of Thalassictis is described as having a protoconid taller than the paraconid, a reduced metaconid, and a short and low talonid with two or three cuspids. Generally, late Orleanian-Astaracian (MN5-8) specimens have an m1 talonid with three cuspids ( Villalta & Crusafont 1943; Viret 1951; Crusafont & Petter 1969; Schmidt-Kittler 1976; Kurtén 1982; Heizmann & Kubiak 1992; Mayda et al. 2015) and Vallesian and Turolian specimens (i.e. MN9-12) have only two cuspids ( Viranta & Werdelin 2003; Bonis 2005). The only exceptions are late Miocene specimens from the Turolian of Dorn-Dürkheim ( T. robusta ; Morlo 1997) and from Chinji ( T. proava ; Pilgrim 1932; for age, see Werdelin & Solounias 1991) that have a three-cusped m1 talonid. In addition, intraspecific morphological variability of the relative development of talonid cuspids is observed in some species. For example, in Thalassictis montadai the m1 may have a tall hypoconulid associated with a tall entoconid (specimens from Spain and Poland; Villalta & Crusafont 1943; Heizmann & Kubiak 1992) or an entoconid smaller than the hypoconid, as in specimens from the Sinap ( Viranta & Werdelin 2003).

The m1 from Küçükçekmece resembles Thalassictis species in having a protoconid taller than the paraconid, a reduced metaconid, and a short and low talonid with two cuspids. In fact in the number and relative development of the talonid cuspids, it differs from T. proava and T. certa and resembles late Miocene specimens assigned to T. montadai and T. spelaea . The m1 from Turkey differs from species of Thalassictis in having a longer paraconid relative to the protoconid (measured parallel to the alveolar margin) and a shorter talonid. Pending discovery of more material, I maintain the taxonomic assignment open.

Malik & Nafiz (1933: pl. 12, fig. 5) assigned to Ictitherium sp. an incisor and a p4 (L: 19 mm; w: 11 mm) that could belong the same species. This is reported in the published faunal lists of Küçükçekmece (e.g., Yalçınlar 1954; Ozansoy 1957). These specimens were destroyed by fire during the last century. Nicolas (1978) also listed Ictitherium sp. cf. I. orbignyi , which is now Plioviverrops orbignyi , but this species is clearly distinct from cf. Thalassictis sp. described here. In Nicolas’ collection stored in the MNHN, there is no evidence supporting the presence of P. orbignyi or a closely related species.

Figures

FIG. 7. — A-C,cf.Thalassictis sp.: Kadi Mezarligi Quarry unnumbered,right m1 in labial (A), occlusal (B), and lingual (C) views;D-N, Machairodus aphanistus (Kaup, 1832): MNHN.F.TRQ1214, right p4 in occlusal (D) and labial (E) views; TRQ1213, right m1 in labial (F) and occlusal (G) views; TRQ1215, right P4 in occlusal (H), lingual (I), and labial (J) views; TRQ694, fragment of right Mt III in proximal (K) and anterior (L) views; TRQ700, proximal fragment of proximal phalanx in proximal (M) and anterior (N) views. Scale bars: 10 mm.