Mustela putorius Linnaeus, 1758

Marciszak, Adrian, Hilpert, Brigitte & Ambros, Dieta, 2024, The remarkable record of mustelids from Hunas (Bavaria, Germany), Comptes Rendus Palevol 23 (23), pp. 339-383 : 348-350

Mustela putorius Linnaeus, 1758

( Fig. 5C, D)

Putorius cf. stromeri Heller, 1983: 207 ; fig. 44; pl. 6/9-15; table 27. – Groiss 1983: 354; table 48. – Koenigswald & Heinrich 1999: 95. – Rosendahl, Ambros, Hilpert, Hambach, Alt, Knipping, Reisch & Kaulich 2011: 19; table 3/2.

Mustela cf. stromeri Ambros, 2006: 36 ; fig. 42-1/2/3; table 53.

Mustela putorius Ambros 2006: 36 .

Putorius stromeri Baumann, 2011: 8 .

REFERRED MATERIAL. — 2 C1, maxilla fr., 3 mandibles, baculum, 2 × metacarpal 4 and metacarpal 5 .

DESCRIPTION

Among the 10 bones assigned to M. putorius , the most interesting and informative are two mandibles and one mandible fragment. The mandibular body is elongated and high, the corpus height decreasing slightly distally, and is the smallest in the middle length of m1. The body is relatively high and thick, and the thickness increases slightly into the distal direction. The ventral margin deviates dorsally, with a constant lateral thickness along most of its length. The margin is slightly curved, with maximum convexity under m1. The symphyseal area is elongated and relatively robust. Starting from the symphysis, on the mandibular body running moderately developed, longitudinal, lingual furrow.Two oval-shaped mental foramina are located on the buccal side. The larger mesial one is below p2, while the smaller, distal one is below the distal root of p4. The mesial edge of the masseteric fossa reaches m2, and it is rounded and rather deep. The tooth row is straight in the occlusal view, with only the p2 crown forming an angle of 50-60° with the rest of the teeth. Distal parts of p3 and p4 are oriented disto-buccally. They are tightly spaced to each other.

The c1 tooth is flattened laterally and relatively short mesio-distally, with a well-developed cingulum. The oval, two-rooted p2 is large and weakly reduced. The two-rooted p3 is low and narrow and bears an elongated, weakly developed distal cingular projection. It has a strong, irregular shape in the lateral view. Its lingual margin is convex, mesial and distal margins are rounded, while on the buccal margin occurs a moderate concavity. The p4 tooth is two-rooted and narrow, with a high, prominent protoconid, which is separated from the surrounding cingulum by a shallow, V-shaped valley. A stronger cingulum is present in the mesial and distal margins of the crown. In the p4 of the HHu 4605 individual, the mesial margin of the tooth is blunt, buccal straight, while the distal margin is arched. The first half of the lingual margin is straight, but the second half is strongly widened disto-lingually, and a well-developed convexity occurs on this part.

The occlusal outline of the HHu 4606 p4 is similar, but the convexity is better developed on the buccal side, and the lingual bulge is well marked. The well preserved m1 of HHu 4605 is elongated and robust, with rounded mesial and blunt distal margins. The buccal margin is concave, while most of the lingual margin is straight, with a prominent, median bulge. The m1 tooth has an elongated and low paraconid and prominent protoconid. Both the main cusps are separated by a deep valley, and the distal wall of the paraconid and mesial wall of the protoconid form an open angle. The trigonid is relatively long and high in relation to the tooth length, while the talonid is trenchant, moderately long and narrow. The talonid bears a large and dominant hypoconid, which is slightly connected with the distal cingulum.

REMARKS

The Hunas polecats were small, robust individuals. Heller (1983d, e) conducted detailed morphometrical analysis of both mandibles and concluded that they represented the Early Pleistocene species Mustela stromeri Kormos, 1934 ( Putorius cf. stromeri according to Heller 1983d, e). He compared the Hunas polecat with the material of Mustela eversmanii (Lesson, 1827) from Hohlefels, Mauer, Sirgenstein and Weimar-Ehringsdorf ( Soergel 1917) and M. stromeri from Villány 5 and Beremend 5 ( Kormos 1934). For comparison, he used 14 individuals of the extant M. eversmanii and 89 extant specimens of M. putorius from Silesia (SW Poland), taken from Soergel (1917).

Kormos (1934) described M. stromeri as a small polecat, with elongated, narrow and tear-shaped infraorbital foramen, straight upper teeth row, large P2, M1 with broad trigon, elongated and slender mandibular body, narrow m1 with a small bulge in the place of the non-existing metaconid and with a high, broad and long talonid. Heller (1983d, e) described two mandibles as belonging to this species. He determined them as M. stromeri based on their small size, slender but thick body mandible (especially strong thickening under m1), strong cingulum on p3, p4 and m1, and narrow m1 with broad, long and less trenchant talonid. However, revision of the European occurrence of M. stromeri showed that some specimens, previously assigned to this species might in fact represent Mustela plioerminea Stach, 1957 , Mustela strandi Kormos, 1934 or even other, related forms. Such a statement was found, e.g. for the material from Osztramos 7 ( Jánossy 1978). On the other hand, material from Erpfingen 3 seems to belong to some intermediate form.

The elongated symphyseal area is moderately massive, as in M. putorius , and stronger in HHU 4606. It is intermediate between very robust symphysis of M. eversmanii and elongated, rather weak symphyseal area in M. stromeri . In Hunas polecats, the masseteric fossa is quite deep, with a rounded mesial margin, reaching the m1/m2 boundary (HHU 4606) or only m2 (HHU 4605) ( Fig. 5). Although variable, such morphology of the masseteric fossa is characteristic for M. putorius . In M. stromeri it is shorter and shallower, maximally reaching m2, with a triangular mesial margin. In M. eversmanii it is noticeably deep and long, and its mesial margin is rounded. The lower surface is extended and forms a flat surface of a rectangular shape for the attachment of powerful muscles. Mustela eversmanii also possesses a strong longitudinal, lingual furrow of the mandibular body. This structure in the form of a gentle arc runs from the symphysis along the whole mandibular body. In M. putorius this lingual furrow is weaker, however, the degree of development of this structure in this species is variable. Together with individuals with a strong lingual furrow, many specimens show weak development. In M. stromeri this structure is usually absent, and if already present, is noticeably weakly developed. In both Hunas specimens the furrow is moderately developed ( Fig. 5).

Also, analysis of the dental material shows strong affinities of Hunas polecats to M. putorius , like in the moderately massive p4 and m1 with long and moderately robust trigonid and short and reduced talonid. The values of the two main indexes describing m1, the talonid breadth/length to the trigonid breadth/length, are above those characterised M. eversmanii in both specimens, but corroborate with those of M. putorius ( Table 4). Simultaneously, they are distinctly below the indexes of M. stromeri , and a low degree of evolution can be seen in the morphology of m1, with an elongated and low crown, proportionally short and weak trigonid and long and narrow talonid. A higher evolutionary level, also represented by specimens from Hunas, can be seen in M. putorius , for which indexes showed intermediate values between primitive M. stromeri and the most advanced and specialised M. eversmanii . The last polecat is characterised by particularly enlarged and robust lower carnassials, an adaptation to crushing skulls and bones of large prey ( Rempe 1970). All those aforementioned features allow us to determine the Hunas polecats as M. putorius .

When comparing the Hunas specimens with three polecat species, it is clear that the individual strongly resembles M. putorius and differs from M. stromeri and M. eversmanii in many morphometrical features. The results are in clear opposition with Heller’s (1983d, e) determination ( Table 4). Metrical values showed that the Hunas individuals were small, comparable in size with ♀♀ of extant polecats and exceed values obtained for M. stromeri . The mandibular body of M. stromeri is elongated and slender, and the corpus height is roughly constant on the whole-body length. The body height after m1 for the Hunas specimens are 7.49 mm (HHu 4605) and 7.66 mm (HHu 4606), which exceeds values of M. stromeri , following the smallest ♀♀ of M. eversmanii , but well corroborated with the values of M. putorius ♀♀ ( Table 4).

Among three polecats, M. eversmanii possesses a particularly high and thick mandibular body. The body height measured after m1 (measurement no. 14) is very useful in species identification. Values below 8.0 mm almost always indicate M. putorius , while values greater than 9.5 mm almost exclusively allow classification of the specimen as M. eversmanii ( Marciszak 2012; Crégut-Bonnoure et al. 2018).Research on large samples of both species showed that the measurement is also correlated with age and individual variation. On rare occasions, some huge individuals with comparatively not very high mandible bodies are also known ( Marciszak 2012). An index of L m1 to the mandible body height measured after m1 is also useful. Its mean value for M. eversmanii is 92.1, while for M. putorius the mean is 114.6 ( Table 4). The data showed that ratios of both polecats overlap very little. The Hunas specimens with ratios of 104.9 and 109.9 are much closer to the mean of M. putorius than to M. eversmanii ( Table 4). The low value of this index in M. stromeri is not related to the massive mandibular body like in M. eversmanii , but to its slender and elongated build.