Ursus arctos priscus Goldfuss, 1818
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publication ID |
https://doi.org/ 10.26879/581 |
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persistent identifier |
https://treatment.plazi.org/id/1766284A-FFF8-DB4B-FEA4-98BDFC2AFF18 |
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treatment provided by |
Felipe |
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scientific name |
Ursus arctos priscus Goldfuss, 1818 |
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Ursus arctos priscus Goldfuss, 1818
Figure 3 View FIGURE 3
Specimens. Crown of the right m2 (JSJ/Us/1).
Measurements. 1, 32.78 mm, 2, 17.51 mm; 3, 20.94 mm; 4, 15.02 mm; 5, 12.09 mm; 6, 20.01 mm; 7, 20.86 mm. See Appendix 2 for measured parts.
Description. The single m2 of exceptionally large size is the only remains of Ursus arctos from Solna Jama ( Figure 3 View FIGURE 3 ). Its general outline is typically arctoid, with the posterior part of the crown only slightly broader than the anterior one. In the cave bear the posterior tooth part is much broader and wider on the buccal than in the examined individual. The anterior and posterior margins are rounded, the lingual edge is almost straight, while the buccal side of the crown is curved in its posterior part. In occlusal view, the tooth appears solid and bulky. The surface morphology is complicated, but much less so than in U. spelaeus . The metalophid complex is complicated, and represents morphotype D. The large, rounded and high protoconid is connected with the metaconid by an almost straight, thick ridge. Between the two main cusps, also two smaller, accessory cusplets are present: a smaller, rounded entprotoconid and a flat, elongated entmetaconid. The frontal ridge is packed with about a dozen cusplets of different sizes, connected and closely associated with each other, oval-shaped and rather low. The trigonid surface between this ridge and the metalophid complex is complicated by a few ribs and grooves, and the overall surface is quite deeply concave. The metastylid is longer but lower, with simple structure, with three metastylids. The median one is the largest and the highest, while the other two are lower and elongated. This structure lacks any other accessory cusplets, such as entoconid, metaconid or mesostylid, which are characteristic of stratigraphically older forms. The mesolophid represents primitive morphotype B, with a simple mesolophid, developed into a semicircular, thick ridge. The enthypoconid complex has a complicated structure (morphotype C/D), with a well-developed, large hypostylid. This cusp is accompanied by a few thick, long ridges. The hypoconulid is present, with a somewhat “cusplet”-like structure situated close to it. Its general shape and morphology indicate an arctoid bear, even if the measurements of this single tooth correspond to the respective large-sized teeth of the U. spelaeus . This was already observed by Sabol (1999, p. 88): “Sometimes the teeth of the subspecies U. arctos priscus have morphological signs, which are common in the species U. spelaeus too.”
Remarks. Since the beginning of systematic cave research in the early nineteenth century, bear remains were found in vast numbers. The Ursus spelaeus had been known for a long time from different paleontological sites across Europe, when a distinct kind of bear was discovered. The second bear was usually smaller, with a rather flat forehead and arctoid-like morphological features. It was described by Goldfuss (1818a) under two different names. Thus from the very beginning the issue of U. arctos taxonomy was controversial. After recent re-examination, finally the name U.
MARCISZAK, GORNIG, & STEFANIAK: MAMMALS FROM SOLNA JAMA CAVE arctos priscus Goldfuss, 1818 was established as senior, firstly used to designate a new form ( Pacher, 2007).
The two main problems faced by scientists dealing with Ursus arctos taxonomy are the lack of well-specified morphometric characters and the absence of morphological features, which would allow to distinguish different forms/subspecies. As observed by Kurtén (1959, p. 81): “The bears in particular have been almost fantastically misinterpreted by incompetent taxonomists.” A single species, U. arctos , was split into more than 150 so-called species, forms, subspecies and even several genera. Some large, late Pleistocene individuals are so different from the modern, European specimens that sometimes in the past really bizarre hypotheses were created. Based on their flat crania (missing glabella), dentition morphology and the supposed late Pleistocene age, it was concluded that they must have belonged to a hybrid between U. spelaeus and U. arctos or, less likely, to a not yet fully grown U. spelaeus ( Ehrenberg, 1929) .
Fossil and subfossil specimens from Central European archaeological and paleontological localities can be divided into two main groups and classified based on their morphometric and morphological characters. The first group represents the huge, primitive U. arctos priscus , dated as the late middle and late Pleistocene. Most of them are dated as younger than 100 Ka (somewhere between 70 and 20 Ka), but bears from a few localities like Biśnik or Południowa Caves are almost certainly older. The second group includes individuals whose smaller and slighter build places them in the nominate subspecies U. arctos arctos , recently occurring in Central Europe. Almost all of them are younger than 15 Ka, but single individuals may be slightly older.
According to Wojtal et al. (2015), the Polish cave sites indicate that Ursus arctos may have replaced U. ingressus in the second half of the last glacial, but this scenario is not obvious and needs further verification. The oldest C14 date for U. arctos in Poland, Kraków Spadzista: 24360 ± 160 cal. BP, is almost within the range of the youngest dates obtained so far for U. ingressus from Poland: Komarowa (24550 ± 220 cal.BP) and Deszczowa (24580 ± 200 cal.BP) caves ( Wojtal et al., 2015). A much older (36500 ± 800 cal. BP) date was obtained from an incisor from layer 2g of Mamutowa Cave. All these dates suggest the occurrence of U. arctos also in cold phases of the last glacial, but they do not resolve the main problem of the cooccurrence of both bears. Some radiocarbon dates from open and cave localities are relatively young, and are certainly beyond the extinction dates of U. ingressus ( Wiśniewski et al., 2009) .
Another important issue is the large size of the examined m2 from Solna Jama, and of some populations of late middle and late Pleistocene U. arctos in general (e.g., Mostecký, 1963; Musil, 1964; Ballesio, 1983; Musil, 1996; Sabol, 2001a, 2001b; Rabeder et al., 2009). The size may have been associated only with the influence of temperature; according to the Bergman rule larger individuals are found in harsher climate. However, the matter is more complicated, due to the fact that large forms are also known from interglacial/interstadial periods. It seems likely that the large size was also associated with a high-protein diet, which the huge bears derived from two sources: hunting and kleptoparasitism. They could roam vast open areas in search of prey and food, also taking advantage of seasonal abundance of fish, berries etc. Their size was of considerable advantage during confrontation with other predators, and the abundance of large herds of hoofed mammals could provide the necessary amount of food to survive for such a large predator. The retreat of the glacier was followed by rebuilding of the fauna; the open grasslands were replaced by thick forests, with numerous but scattered small and medium-sized species. The world around the huge, hypercarnivorous U. arctos changed, and now it offered much more favourable conditions for smaller and more versatile animals. The huge, primitive, carnivorous U. arctos priscus was replaced by a smaller, more omnivorous U. arctos arctos , which then survived to this day. It is not clear if it was competition that was concerned, or filling the free niche by one form, following the decline of another. Preliminary results of isotopic studies ( Krajcarz et al., 2014c) also confirm a higher proportion of meat in the diet of the Pleistocene forms. In conclusion, we agree with many earlier authors (e.g., Thenius, 1956; Mostecký, 1963; Musil, 1964; Musil, 1996; Sabol, 2001a, 2001b; Pacher, 2007) on that the true U. arctos priscus may have represented quite a different form, that was adapted to open, steppe-like habitats.
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