Mustela erminea 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 : 351-352

Mustela erminea Linnaeus, 1758

( Fig. 7A)

Mustela aff. palerminea Heller, 1983: 200 ; fig. 44; pl. 6/5-8; table 26. – Groiss 1983: 354; table 48. – Koenigswald & Heinrich 1999: 94. – Ambros 2006: 35; fig. 41-3/7/8; tables 47, 78, 85. – Rosendahl, Ambros, Hilpert, Hambach, Alt, Knipping, Reisch & Kaulich 2011: 19; table 3/2.

Mustela palerminea Baumann, 2011: 8 .

REFERRED MATERIAL. — Humerus, ulna, femur, tibia, 3 metapodials .

DESCRIPTION

Long and narrow humerus has a flat and narrow head. The greater tubercle extends distally along the side of the articulation surface ( Fig. 6). The well-marked neck is directed distally. The lesser tubercle is well-developed. The rugose area on the inner surface of the shaft for the attachment of the inner humeral head of the triceps muscle is prominent. The lateral epicondylar crest is strongly developed towards the lateral epicondyle from the last distal fourth. The medial epicondylar crest is prominent and has a narrow supracondylar foramen. The strong medial condyle is situated slightly back, while the lateral condyle is deeper in the mesio-distal direction. A rounded and shallow coronoid fossa does not connect with the wide and deep olecranon pit ( Fig. 6). The radius is thin and flattened dorso-ventrally, and it has a slightly concave ventral surface ( Fig. 6). The moderately large head has a shallow and rounded articular surface. It is mesially collared by a moderately prominent coronoid process.

The articulation surface for the lesser sigmoid cavity is relatively large. The distal end is widened laterally, with a well-marked elliptical glenoid cavity, framed by a rough condyle on the ventral and medial sides. The facet for the ulna is small, while the styloid process is well-developed. The grooves for the extensor muscle tendons, extensors carpi radialis longior and brevior muscles are broad and deep. The scapholunar articulation area is relatively short and broad ( Fig. 6). The ulna is massive, with a strong but short proximal end ( Fig. 6). The surface for attachment of the scapular head of the triceps muscle is broad and strongly rugose. The olecranon has a quadrilateral shape with its apex hollowed out in part of a small cavity bordered by two fairly prominent tubercles. The shaft is curved in the lateral and medial view and massive in its longitudinal extent. The articulating surface for the radius is large, while the articulating surface for the pisiform is quite narrow. The distal end is characterised by a significant protrusion of the ulnar styloid process ( Fig. 6).

The long, cylindrical femur possesses a spherical head with a prominent neck ( Fig. 7). The trochanteric fossa is narrow and deep. The lesser trochanter is a slight conical prominence. The shaft is slightly bowed in its longitudinal extent. The greater trochanter rises distinctly above the head level and is obliquely truncated on its lateral side. The surface of the trochanter extends further down the proximal extremity of the femur. The tibial articulations are nearly equal in size. At the distal end, the condyles are separated by a broad and deep groove. The lateral condyle is slightly more developed than the medial one ( Fig. 7). The body of the long and thin tibia is triangular in its proximal third, slightly convex medially, with a large tibial fossa from the lateral side ( Fig. 7). The distal surface below the head is narrow and shallow. The tibial crest is well marked but relatively short. At the distal end, the articular surface consists of two separate grooves. The medial throat is deeper than the lateral one. The grooves for tendons of the flexor longus digitorum and tibialis posticus muscles are well defined at the distal epiphysis. The notch incising the mesial border of the distal surface is quite small ( Fig. 7).

REMARKS

A permanent problem in faunistic analyses is distinguishing small species of the genus Mustela . Many authors made several attempts, resulting in the conclusion that the only reliable criterion is size. This was largely the case with the rich material from Hunas, where Heller (1983d, e) also attempted to classify this material. No cranial material of M. erminea was found in Hunas. Apart from the abundant cranial material, attributed exclusively to M. nivalis , even more numerous postcranial skeletal elements in Hunas were found. It is represented mainly by long bones, but also some pelvis and metapodials. They are well preserved and about one-third are complete. No substantial differences between M. erminea and M. nivalis were found in the morphology of the postcranial bones. The variability of the features is so high that it is impossible to establish any characteristics for that species. In this context, the only reliable criteria for distinguishing the postcranial elements of small Mustela species are dimensions.

A similar situation was found for the material of the Early and early Middle Pleistocene M. palerminea and M. praenivalis , where size was the only criteria for their classification ( Rabeder 1976; Wiszniowska 1989; Marciszak et al. 2021). Long bones are recognisable and measurable markers for species determination. Small mustelids are characterised by extreme sexual dimorphism, with ♂♂ 1.5 times larger than ♀♀ ( Kratochvíl 1977a, b; King 1989; King & Powell 2007). The metrical analysis of sexes’ long bones of M. erminea and M. nivalis from Hunas is based on the differences in size of ♂♂ and ♀♀ in extant, Silesian populations. These differences were shown in all long bones, and the most important was greatest length (L). This value was lower in ♀♀ than♂♂ in all analysed bones ( Table 5). The long bones differ significantly in size like in extant forms, where size ranges of M. erminea ♀♀ and M. nivalis ♂♂ do not overlap ( Table 5). Since the individuals of M. erminea and M. nivalis from Hunas are comparable in size with the extant, Silesian populations, respectively, it is possible to track sexual dimorphism based on long bones. It is possible even in the case of incomplete bones, since the proportions of bone parts are quite constant ( Reichstein 1986; Marciszak 2012; Marciszak et al. 2021). It allows us to estimate the total length of such bones and also use them in the analysis ( Table 5).

The analysis of the dimensions of the numerous postcranial materials allowed to include for M. erminea only a few bones. Between two humeri, the larger (HHu 4207, L 34.44 mm) was determined as ♂, while the smaller (HHu 4569, L 27.81 mm) was assigned as ♀. A single incomplete radius (HHu 4301) and three femora, one intact (HHu 4205, L = 35.02 mm) and two incomplete (HHu 4209 and HHu 4496), showed intermediate values, so they cannot be properly sexed. The proximal half of the sole tibia (HHu 4206) belongs to a moderately large individual, most probably ♀ ( Table 5). Because metapodials of the extant M. erminea cannot be reliably sexed, we did do this for the material of this species from Hunas. The study of the postcranial material of M. erminea from Hunas does not show a predominance of♂♂ or ♀♀ and shows the presence of medium-sized individuals ( Table 5). Metrically and morphologically, they are indistinguishable from the extant Silesian population.