Vulpes lagopus (Linnaeus, 1758)

Marciszak, Adrian & Kropczyk, Aleksandra, 2025, Canidae (Carnivora, Mammalia) from Niedźwiedzia Cave (Silesia, southwest Poland), Palaeontologia Electronica (a 15) 28 (1), pp. 1-33 : 18-21

Vulpes lagopus (Linnaeus, 1758)

( Figures 9–10 ; Table 4; Appendix 1)

Material. The material ( NISP 22, MNI 4; left/right bones are given in brackets) includes three maxillae fr. (2/1), one M1 (0/1), one M2 (0/1), seven mandibles (4/3), three humeri (1/2), two ulnae (1/ 1), two femora (2/0), and three tibiae (2/1).

Description. The premolar teeth row is straight, and the teeth are set loosely. The elongated and narrow P2 and P3 bear an elongated distal cingular projection. The prominent protocone is situated almost exactly in the middle axis of the crown and is pushed more mesially. The small mesio-lingual prominence of the cingulum forms a faint mesial crest to the apex of the protocone of the P3. The cingulum is weakly developed on the lingual side. The relatively long and narrow P4 has almost straight buccal and lingual margins. The paracone is high and well separated from the proportionally short and low protocone. Its length is smaller than the distal breadth of the crown. The cingulum is strongly developed on the lingual margin of the metacone. The triangular M1 has a broad, moderately expanded trigon and a long and wide talon. The paracone is large and high, exceeding the metacone slightly in size and height. The small and low protocone is connected by a thin and sharp crest with the small entocone. A small protoconule is situated on the mesio-lingual part of the talon. The low and elongated hypocone is a strong crestlike structure. The main basin between the trigon and the talon and between the protocone and hypocone are deep. There is a well-developed mesio-buccal cingulum. The M2 is more strongly reduced compared to the size of M1, with a wide talon oriented strongly disto-lingually. All main cusps are low with the paracone being larger and higher than the metacone. There is no connection between the protocone and the metacone. The trigon fossa communicates with the talon fossa by a narrow, V-shaped valley ( Figure 9 ).

The mandibular corpus is deep and stout, becoming medio-laterally thicker ventrally and its height gradually increases distally. Two mental foramina are located below the mesial roots of p2 and p3 ( Figure 9 ). The rounded mesial edge of the deep masseteric fossa reaches the m3. The lower mandibular body margin is straight, only in one specimen forms a gently curved arch, with the maximum under the m1. The symphysis part is elongated and narrow. The cheek teeth row is straight, and the premolars are located more buccally in relation to the molars and are tightly arranged.

The c1 is long and robust, with an elongated and hook-shaped crown ( Figure 9 ). The p1 is an elongated, oval, small, and one-rooted tooth. The p2 is high-crowned, with the protoconid strongly displaced mesially. The crown is elongated and narrow, gently convex buccally and with a weak median convexity. It has an elongated distal cingular projection. The elongated and narrow p3 gently widens distally. The protoconid is also displaced mesio-medially, but less so than in p2. The high-crowned p4 has a protoconid strongly displaced mesio-medially. A prominent cuspid is present after the protoconid. The crown is slightly broadened in the distal direction, with straight buccal and lingual margins. The elongated and narrow m1 has a massive and high trigonid and a proportionally long and low talonid, slightly narrower than the trigonid. The large and trapezoidal metaconid is moderately distinct from the protoconid. The cingulum is moderately developed. The hypoconid is large and high, while the entoconid is lower and smaller. The talonid basin is round, smooth, and wide, partially enclosed lingually by the entoconulid ( Figure 9 ). The elongated and narrow m2 has a slightly irregular, rounded occlusal outline. On the trigonid are located a larger and higher protoconid mesio-buccally and a lower and smaller metaconid medio-lingually. The talonid is narrower, with a conical and low hypoconid and a rudimentary entoconid. The moderately developed cingulum is stronger only on the distal margin. The m3 has an oval outline and bears two equally sized cusps, the protoconid, and the metaconid.

Comparison. The dentognathic material from Niedźwiedzia Cave metrically and, above all, morphologically corresponds to Vulpes lagopus . Numerous features that distinguish the dental material of both foxes from Niedźwiedzia Cave have been found.

Compared to Vulpes vulpes , V. lagopus possesses:

(1) more tightly set teeth;

(2) less elongated and expanded crowns of I1–I3 with weak lingual cingulum;

(3) shorter and less curved C1 with weak lingual cingulum;

(4) narrower and more reduced P1;

(5) P2 relatively short and low, not widened distally;

(6) broader and more compact P4, with short protocone that does not protrude far mesio-lingually, less projected metastyle, and without lingual cingulum;

(7) M1 with distinctly less expanded trigon, more reduced metacone and protocone, and a mesial cingulum that is not connected to the hypocone forearm;

(8) M2 with distinctly narrower trigon, a completely interrupted protocone–metacone connection, and a trigon fossa that is connected to the talon fossa;

(9) mandible with straight lower margin and lower and narrower mandibular body in its mesial part;

(10) narrower and less curved c1;

(11) more compact and broader p2–p4, with lessdeveloped distal accessory cuspulids;

(12) narrower m1 with less positioned metaconid and no connection between the entoconid and hypoconid; and

(13) narrower m2.

Postcranial material. In addition to the described dentognathic remains, the postcranial material of foxes from Niedźwiedzia Cave is also abundant. It is represented by long bones and calcanei, mainly well preserved and often complete. However, most authors concluded that there are no substantial differences between Vulpes vulpes and V. lagopus in the morphology of the postcranial bones (Mostecký, 1969; Beneš, 1975). The variability of particular features is so high that it is impossible to establish any characteristics for the particular species. In this context, the only reliable criteria for distinguishing the postcranial elements of Vulpes species are dimensions. A diagnosis of the postcranial skeleton usually has not been given. Gromova (1950) pointed out that a “distinction is possible on the basis of measurement only, the possibility of confusion of extreme values being considerable.” Additionally, Beneš (1975) sum-

marised this pattern as follows: “The great unifor-

mity of canids leads either to underestimation or overestimation of morphological or metric differences. This results either in the endeavour to concentrate all Pleistocene foxes into one or two recent species, or the creation of a great number of new species based on subordinate features only.”

Apart from the uniform morphology and great variability, there is also the problem of the oftenfragmentary nature of the analysed postcranial material. However, this problem can be overcome by estimating the total length of a given bone based on the preserved fragment. Analysis of the extant series of Vulpes vulpes from Silesia showed that the mutual proportions of length and width of a given skeletal element show a relatively small range of variability and are quite constant. Using the obtained constants, it is possible to estimate the total length with statistically significant probability and compare it to the range of variability of a given species. Body size and sexual dimorphism is marked enough in foxes to separate V. vulpes and V. lagopus and to separate males and females based on long bones (Monchot and Gendron, 2010). Metrically, there is some overlap between V. vulpes and V. lagopus , but it is possible to distinguish the long bones of these two species. The bones of V. lagopus are always smaller than those of V. vulpes of the same sex. No overlap occurs in the ranges of measurements between the two species and sexes, except for a very few parameters, and even that overlap is rather little (Monchot and Gendron, 2010). Long bones are recognisable and measurable markers for species determination ( Figure 10 ). Foxes are characterised by moderate sexual dimorphism, with male being 10–15% larger than females (Monchot and Gendron, 2010). The metric analysis of sexes of V. vulpes and V. lagopus from Niedźwiedzia Cave is based on the differences in size between males and females of extant foxes ( Table 4). These differences were shown in all long bones, and the most important was the greatest length (GL). This value was lower in females than in males in all analysed bones ( Figure 10 ).

For the humerus, the two main indexes are the ratio of the length of the proximal epiphysis to the greatest length (pL/GL) and the breadth of the distal epiphysis to the greatest length (dB/GL) ( Table 4). The first ratio (pL/GL) is 20.4 (18.7–22.3, n = 68), while the second index (dB/GL) is 16.6 (14.8–18.2, n = 68). Of the five fox humeri from Niedźwiedzia Cave, two were identified as Vulpes vulpes , such as the huge complete humerus (JN.2.10) with a GL of 166.14 mm, which even slightly exceeds the size of the extant Silesian V. vulpes , and belongs to a male ( Table 4). The second specimen (JN.2.24) is smaller, with an estimated GL of 135 mm (125–145 mm), which may indicate both a small male and a large female, but rather closer to a male. Three humeri were assigned to V. lagopus , two of which have similar dimensions: JN.3.6 with a GL of 112.76 mm and JN.3.21 belonged to males, whereas the distinctly smaller third bone (JN.3.22) was a female.

The morphological differences are much less pronounced. Beneš (1975) found that the tuberculus major on the proximal epiphysis is larger and more expanded in relation to the surface in Vulpes vulpes than in V. lagopus . Simultaneously, all humerus edges of V. lagopus are more sharply developed and marked than those of V. vulpes . Our observations showed that both features, however, are quite variable, and can be traced only with difficulty. With regard to the metric differences, confusion of the humerus between V. vulpes and V. lagopus is little probable.

All three ulnae from Niedźwiedzia Cave are incomplete and are represented only by proximal parts. The two larger (JN.2.2 and JN.2.26) were assigned to Vulpes vulpes , while the smaller one (JN.3.4) to V. lagopus . As in the case of the humerus, there is a clear distinctness in the GL and pL between both fox species. Gromova (1950) found that the ulna of V. lagopus can be morphologically distinguished from that of V. vulpes on the basis of two main criteria. The central part of the diaphysis of V. lagopus is mostly strongly flattened, so that the largest anterio-posterior diameter rarely attains less than 140% of the transverse section. The posterior part of the olecranon processes in V. lagopus is raised only slightly. In V. vulpes , the dorsal points are highly raised, to the same levels as that or the olecranon itself, and between the posterior points and the olecranon there is a saddle-like depression (Beneš, 1975). Our observations did not confirm this distinctness with certainty and those features showed some degree of variation. Additionally, they are not regarded as very useful because the olecranon processes are often mechanically damaged. In this context, the metric differences are much more indicative ( Table 4).

The best preserved among all long bones of foxes are the femora represented by four complete specimens. The analysis of their taxonomic affiliation well illustrates the complexity of correct identification of the fox material. The largest bone (JN.2.22), with a GL of 133.82 mm, falls into the size variability of Vulpes vulpes as a small male or a large female. The two smaller femora, JN.3.19 with a GL of 114.16 mm and JN.3.20 with a GL of 105.64 mm, were identified as V. lagopus . The identification of the specimen JN.2.23 with a GL of 119.72 mm is problematic, which falls in the range of variability of V. vulpes females and V. lagopus males. The value is close to the mean of V. vulpes females and was therefore determined as such. However, it cannot be ruled out that this particular specimen is, in fact, V. lagopus , since no substantial morphological differences have been found between the two foxes (Gromova, 1950; Mostecký, 1969; Beneš, 1975).

Of the four tibiae from Niedźwiedzia Cave, only the largest one, JN.2.3 with a GL of 172.84 mm, represents a robust male of Vulpes vulpes ( Table 4). The other three tibiae (JN.3.16, JN.3.17, and JN.3.18) were assigned to small and mediumsized specimens of Vulpes lagopus . Also, in the case of this bone, no reliable morphological features distinguishing V. vulpes from V. lagopus can be found. Concluding, only metric data are reliable enough to distinguish between the two foxes, while morphological features have little value in taxonomic identification (Mostecký, 1969; Beneš, 1975; Reichstein, 1984; Bisaillon and Deroth, 1979, 1980; Altuna, 2004; Germonpré and Sablin, 2004; Baryshnikov, 2006; Monchot and Gendron, 2010).

Figures

FIGURE 9. Cranial material of foxes from Niedźwiedzia Cave. Vulpes vulpes: A, right mandible (JN.2.34). B, left mandible (JN.2.31). C, right maxilla (JN.2.15). D, right mandible (JN.2.33). Vulpes lagopus: E, left mandible (JN.3.8). F, right mandible (JN.3.2). G, right mandible (JN.3.3). H, left mandible (JN.3.8). I, left mandible (JN.3.10). All individuals showed in the same scale (15 mm), 1 – buccal view, 2 – lingual view, 3 – occlusal view.

FIGURE 10. Comparison of the length (in mm) of long bones in extant Vulpes vulpes and Vulpes lagopus with the fossil specimens of these species from Niedźwiedzia Cave. Extant Vulpes vulpes: black values (♂♂) and red values (♀♀); extant Vulpes lagopus: brown values (♂♂) and blue values (♀♀). Numbers indicate the specimens from Niedźwiedzia Cave.