Thalassictis sp.

Bonis, Louis de, 2005, Carnivora (Mammalia) from the late Miocene of Akkaşdağı, Turkey, Geodiversitas 27 (4), pp. 567-589 : 576-578

cf. Thalassictis sp.

MATERIAL. — Piece of right half mandible with m1 (AK7-107).

A m 1 in a piece of mandible (AK7-107) does not match the Carnivora described above. Smaller than that of Adcrocuta eximia , it is a little larger than Hyaenictitherium wongii ( Fig. 9 ).

DESCRIPTION ( FIG. 9 )

The tooth is in a fragment of mandible with a bit of the ramus but without the inferior part of the corpus. It belongs to a young adult and its morphology is very clear without any trace of wear. The paraconid is short relative to the protoconid. The latter is slightly taller than the former. The occlusal blades of both cuspids are almost in a straight line. The metaconid is reduced and it is sligthly visible in buccal view. There is a moderate buccal cingulum. The talonid is slightly reduced in length and is narrow, tapering toward the distal end. The hypoconid is centrally situated and linked by a small crest to the middle of the distal face of the protoconid. The entoconid is small and the talonid basin is closed by a clear hypoconulid which bears very tiny cusplets. There is no m2.

COMPARISONS

AK7-107 differs clearly from the species of Ictitherium by the higher trigonid, the reduced metaconid, the reduced talonid and the absence of m2. It differs from Palinhyaena Qiu, Huang F Guo, 1979 (see Werdelin 1988) by the slightly lower trigonid, the less reduced metaconid, the less reduced talonid and the absence of m2. It differs by the same characters from Lycyaena Hensel, 1861 of which the proportions between paraconid and protoconid are different: the paraconid is longer and the protoconid is higher in the type specimen of L. chaeretis ( Gaudry, 1861) from Pikermi, type species of the genus. The buccal cingulum at the base of the paraconid is stronger in the Greek species. The metaconid is more reduced and more distally situated. The talonid is also a little different with a more trenchant hypoconid, a smaller entoconid and a very weak hypoconulid. The absence of m2 is sometimes considered as a character of Lycyaena but it is impossible to know if this tooth is present or not on the two mandibles from Pikermi that I have studied.

The talonid of Hyaenictitherium wongii or H. hyaenoides has quite the same length reduction relative to the trigonid length as that of AK7- 107, and the metaconid is similar but the talonid is broader.

The morphology of the Thalassictis robusta lower carnassial is quite similar to that of AK7-107 ( Kurtén 1982: fig. 1) and the proportions of the talonid length relative to the trigonid are similar but the talonid of T. robusta is less narrow. The T. robusta m1 is smaller than AK7-107 and the m2 is present. The type specimens of T. certa (Forsyth- Major, 1903) was recovered in the late middle Miocene (MN 7-8) of La Grive Saint-Alban (Isère, France). This species was considered the type of the genus Miohyaena Kretzoi, 1938 . The m1 is a little smaller than AK7-107 and the trigonid is higher relative to the talonid which is more reduced. In fact this species does not differ substantially from the proportions of the genus Miohyaenotherium Semenov, 1989 . T. spelaea ( Semenov, 1988) from the late Miocene of Gritsev ( Ukraine) is smaller than AK7-107. T. proava from the late middle Miocene or late Miocene of Pakistan is smaller and the metaconid of m1 is more reduced. The largest species of Thalassictis is T. montadai (Villalta Comella F Crusafont Pairo, 1943) described from Hostalets de Pierola in the late middle Miocene of Spain (Villalta Comella F Crusafont Pairo 1943) under the name Ictitherium montadai . It is a little smaller than AK7-107 but the morphological characters of the m1 seems to be quite similar except that the metaconid of m1 is a little less reduced in the Spanish species and the talonid is more reduced (J. Morales in litt.). Nevertheless, the absence of m2 on the Akkaşdagwı carnivore seems to be a great difference but we know that this tooth is quite reduced and regressive in the species of Thalassictis . The same species has been identified as Progenetta montadai vallesiensis in the early Vallesian of Can Barra (San Quirza), Spain (Crusafont Pairo F Petter 1969). The m1 (20/ 10 mm) is smaller than that of AKK- 107. The late middle Miocene Turkish locality Yeni Eskihisar has also yielded remains of T. montadai although attributed to the genus Miohyaena Kretzoi, 1938 . The size of m1 is quite similar to that of Akkaşdagw ı but m2 is present. The Turolian locality Akkaşdagw ı is younger than the Spanish ones with T. montadai as well as the locality Yeni Eskihisar, so if the loss of m2 is not an individual character, it could be a derived feature of a new younger species of Thalassictis . But, however, another specimen identified as Hyaena namaquensis Stromer, 1931 and later referred to Hyaenictitherium (Werdelin F Solounias 1991) seems to be close to AKK- 107 in the morphology of m1. The metaconid seems to be reduced in the same way and the talonid is narrow but it bears three distinct and well developed cuspids. Nevertheless, the m2 is present in the mandible of H. namaquensis although the type specimen is younger geologically than AK7-107 (early Pliocene). Another mandible recovered from the locality of Sahabi (latest Miocene or early Pliocene) first described as Ictitherium (Palhyaena) arkesilai Esu F Kotsakis, 1980 and later referred to Hyaenictitherium namaquensis (Werdelin F Solounias 1991) can be compared to AK7-107. The lower m1 is quite similar in the morphology but it is larger and m2 is present. So with this poor material it is difficult to reach a firm conclusion. Another species, Miohyaenotherium bessarabicum (Simionescu, 1938) , with a relatively high trigonid and short talonid has also been described from localities of Ukraine and Georgia. The m1 can reach 20 mm in length but the morphological characters do not differ substantially from those of some species of Thalassictis . So the relationships between some Hyaenictitherium , Thalassictis , Miohyaena or Miohyaenotherium species are yet unclear. Until the recovering of new documents, it is better to consider the fragmentary mandible AK7-107 as cf. Thalassictis sp. despite the lack of m2.

Family FELIDAE Fischer de Waldheim, 1817

Figures

FIG. 9. — Cf. Thalassictis sp., fragment of right mandible with m1 AK7-107, Akkaşdağı, late Miocene (Turolian), Turkey; A, buccal view; B, lingual view. Scale bar: 3 cm.