Promephitis hootoni Şenyürek, 1954

Bonis, Louis de, 2005, Carnivora (Mammalia) from the late Miocene of Akkaşdağı, Turkey, Geodiversitas 27 (4), pp. 567-589 : 581-584

Promephitis hootoni Şenyürek, 1954

Promephitis hootoni Şenyürek, 1954: 276 .

MATERIAL. — Right half mandible (AK5-674) with i1-m1.

Remains of small carnivorans are quite rare in the late Miocene Turkish localities ( Şenyürek 1952, 1953, 1954; Ozansoy 1965; Schmidt-Kittler 1976; Bonis 1994) so the discovery of a small carnivore half mandible in AK5 yields new insights into this group of mammals in the Near East. This is a well preserved right mandible with the right incisors, the canine, the p2 alveolus and p3- m1 followed by the m2 alveolus. The corpus and the ascending ramus are complete.

DESCRIPTION ( FIG. 14 ; APPENDIX: TABLE 3)

The body of the mandible (corpus) is short, deep (Appendix: Table 3) and robust. The symphysis is steeply inclined and the maximum deep is beneath p3. The inferior border is quite straight under p3 to m2 and ascends steeply under the coronoid process; it ends in a short angular process. The coronoid process (ramus) is tall and triangular, the top not being distally curved. The masseteric fossa is quite shallow but limited mesially along the coronoid process by a strong crest; on the corpus, the fossa ends anteriorly under the posterior part of m2. The lingual surface of the coronoid process is a little hollow which could indicate a strong temporal muscle. The articular condyle is situated a little above the level of the top of the m1 protoconid; it is very extended bucco-lingually. A mental foramen is situated at mid-height beneath the distal root of p3 ( Fig. 14 ).

The incisors are small and much worn. It is impossible to observe any detail on the crowns. Their size increases slightly from i1 to i3. The basal sections of the i1 and i2 crowns are oval, while that of i3 is more rounded. The canine is tall and robust especially at the base of the crown. There is a very smooth distal crest. The crown is oval in cross section but the mesio-distal axis increases greatly from the tip to the base. There is a lingual cingulum. We can see a small, horizontal wear facet on the tip of the canine. There is no diastema between the canine and the premolars, nor between the cheek teeth themselves. The p2 is represented only by a small rounded alveolus which is placed slightly lingual to the rest of the toothrow. The other premolars are reduced and simple without any accessory cuspids and their size increases from p3 to p4. The basal sections of the crowns are egg-shaped with the maximum breadth at the distal part. In lateral view, both p3 and p4 are asymmetric, the distal part being longer than the mesial one. A distal cingulum demarcates a small hollow talonid. The top of p4 is slightly higher than the protoconid of m1. The first molar is low; the protoconid is higher than the paraconid but the latter is partially worn. The metaconid is as tall as the paraconid, robust and situated in front of the distal part of the protoconid but not visible in buccal view. The hollow talonid is as long as the trigonid and surrounded by a crest. The hypoconid is taller and larger than the entoconid and another cuspid situated between the latter and the metaconid. The alveolus of m2 is oval and is not horizontal, but slightly inclined along the ramus. The dentition on the whole shows a crushing adaptation.

COMPARISONS

If we except otters, with whom the Akkaşdagwı mandible shares no characters, three subfamilies of mustelids have crushing dentitions: Leptarctinae Gazin, 1936 , Melinae Bonaparte, 1838 and Mephitinae . Among these we can find some species of a size similar to AK5-674. The differences between species are sometimes tiny and the genera can be put in one subfamily or another depending on the authors’ opinions.

The Miocene Leptarctinae are represented by three genera ( Ginsburg 1999). Trochotherium Fraas, 1870 ( T. cyamoides Fraas, 1870 ) is a very derived carnivore whose mandible is robust like that of AK5-674 but the coronoid process is lower. The base of the canine is large and the premolars, p2 and p3, are reduced. But p4 is larger and more asymmetric, and the lower carnassial has no metaconid and is so inflated that it is difficult to see the demarcation between the other cuspids of the trigonid. This species was certainly a shell crusher. Gaillardina Ginsburg, 1999 is known from “ Mustela ” transitoria Gaillard, 1899 with only a skull from La Grive Saint-Alban (middle Miocene, MN 7-8). The third genus, Trocharion Major, 1903 ( T. albanense Major, 1903 ), is less derived and well known through material from La Grive Saint-Alban in France, Valles Pénédes in Spain ( Petter 1963, 1967, 1976) and especially Steinheim in Germany ( Helbing 1936). The mandible is deep but less so than AK5-674. There is a full premolar dentition and the premolars are larger, p2 is double-rooted and p4 is considerably more than half the length of m1. The carnassial is lower-crowned with a larger metaconid. The talonid is as long as the trigonid with small cusps on the hypoconid ridge. The m2 is double-rooted. Most of the characters are different from those of AK5-674. We must note that Trocharion is a Melinae for Helbing (1927) or Petter (1967), a Leptarctinae for Ginsburg (1999), while for Pilgrim (1932) it is allied to Mephitis E. Geoffroy Saint-Hilaire F G. Cuvier, 1795 .

The Melinae are well represented in the Miocene by several genera. Some have only large species or are known through upper dentitions and cannot be compared to AK5-674. Taxodon Lartet, 1851 is known through two species; one, T. sansaniensis Lartet, 1851 , from Sansan, dated to the middle Miocene (MN 6) and another, T. hessicum Ginsburg, 1999 , from the late Miocene of Spain and Germany (MN 9 to MN 12). The premolars are longer and p4 has a posterior accessory cuspid and a bulging anterior cingulum. There is a deep notch between protoconid and talonid of m1 whose metaconid is more reduced and the talonid a little shorter. Several species belong to the genus Trochictis Meyer, 1842 . They differ from AK5-674 by a slender mandible, the presence of p1, the double-rooted p2, and the longer p3 and p4 ( Meyer 1842; Schlosser 1888; Helbing 1927; Pilgrim 1932; Viret 1933; Petter 1976). Plesiomeles cajali Viret F Crusafont, 1955 is founded on a mandible with m1 from the Vallesian of Spain. The mandible is badger-like, slender with a double-rooted p2 and the m1 has a long talonid with several cusplets on the entoconid edge. Grivamephitis Beaumont, 1973 was first established as a subgenus of Plesiomeles Viret F Crusafont, 1955 . The best known species G. pusilla ( Major, 1903) is a minute one and has a slender mandible, a p4 with a small posterior accessory cuspid and a notch on the distal crest of the crown and a m1 with a metaconid placed rather posteriorly, a longer talonid and cusplets on the entoconid crest. Palaeomeles Villalta F Crusafont, 1943 ( P. pachecoi Villalta F Crusafont, 1943 from the latest middle Miocene) differs from AK 5-674 in a m1 with a more reduced and distally situated metaconid and a huge multicuspid talonid. Promeles Zittel, 1890 species ( P. palaeattica (Weithofer, 1888) and P. macedonica Schmidt-Kittler, 1995 ), both in the late Miocene, are far larger than AK5-674. The mandible is robust but less than in AK5- 674. The top of the coronoid process is rounded and not sharp. The lower p1 is absent, but p2 is double-rooted and the premolars are relatively longer, while p4 has a small posterior accessory cuspid. The metaconid of m1 is posteriorly placed and the talonid longer, with several cusplets on the entoconid edge.

Nowadays, the Mephitinae live in northern and southern America but during the Miocene they were present in Eurasia. They have been described from the late early Miocene of Wintershof- West in Germany with Miomephitis pilgrimi Dehm, 1950 . This primitive species shows some of the main characters of the group. The mandible is robust, the canine is stout and the premolars are reduced. The m1 has a large metaconid and is adapted to a crushing diet. AK5-674 differs from Miomephitis Dehm, 1950 in its deeper mandible, more reduced premolars and the shape of the coronoid process. Proputorius Filhol, 1891 from the late middle Miocene and the upper Miocene is founded on P. sansaniensis Filhol, 1891 . It differs from AK 5-674 in its less robust mandible, double-rooted p2, less reduced premolars with a large cingulum and less crushing m1 with a shorter talonid. There are two other species, P. pusillus (Viret, 1951) and P. medius Petter, 1963 , of which the latter is sometimes considered as belonging to a different genus, Mesomephitis Petter, 1967 . Both have similar characters.

The genus Promephitis Gaudry, 1861 was created for P. larteti Gaudry, 1861 , recovered from the Turolian (MN 12) locality Pikermi. The size is similar to AK5-674,as is the robustness of the mandible and the shape of the coronoid process. But the inferior border of the mandible is not upwardly directed under the ascending ramus. The lower carnassial is also similar to that of AK5-674. We note the same difference for P. alexejevi Schlosser, 1924 from Mongolia which is also larger than AK5-674. The p3 is also shorter relative to m1. P. majori Pilgrim, 1933 from Samos has a less robust canine and smaller premolars relative to m1; the metaconid of m1 is more distally situated. Another species, P. hootoni Şenyürek, 1954 , was recovered from Asia Minor in the Turolian locality of Küçükyozgat. The shape of the mandible is very similar to that of AK5-674 but the corpus is a little less robust (robustness index under m1 = 79.5 against 99); the size of the dentition is also similar. For Şenyürek, this species differs from P. larteti , whose lower p2is missing and whose m2 alveolus is horizontal. In P. hootoni this alveolus “is seen to be slanting upward, in side view”. It differs also from P. majori in its less reduced lower premolars. Two other species, P. maeotica Alexejew, 1916 and P. malustenensis Simionescu, 1930 , are larger. The latter one has a large distance between p4 and m1; the m1, which has a cingulum, is larger absolutely and relatively, the metaconid of the carnassial is also smaller than that of AK5-674 and this specimen could belong to another genus. In summary, I refer the specimen from Akkaşdagwı to Promephitis hootoni . The skunks seem to have been quite diversified in Eurasia through the late Miocene, but the differences between the species are slight. It seems that they invaded the New World before becoming extinct in the Old one after the Pliocene if the Asian genus Mydaus F. Cuvier in Geoffroy Saint-Hilaire F F. Cuvier, 1821 is closer to the badger than to the skunks.

We can remark that Promephitis gaudryi Schlosser, 1902 , described from an isolated m1 from the Vallesian of Melchingen, seems very similar to the m1 of Trocharion albanense and does not belong to the Mephitinae .

Figures

FIG. 14. — Promephitis hootoni Şenyürek, 1954, right half mandible with c, p3-m1 AK5-674 (drawings), Akkaşdağı, late Miocene (Turolian), Turkey; A, lingual view; B, buccal view; C, occlusal view. Scale bar: 1 cm.