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Revision of the Silesian bear fauna, based on material from 152 sites, mainly cave and karstic localities, and also archaeological and open-air sites, shows the presence of 13 forms and species. These records encompass the last 16.5 Ma and may be divided into five main morphophyletic groups. The oldest bears, represented by the genera Ballusia and Ursavus , are dated to 16.5–11 Ma, and belonged to the stem forms of the subfamily Ursinae. After a break of 6 My, the earliest members of the genus Ursus appeared, and all known Pliocene bears in Silesia belong to the genus Ursus were identified as Ursus minimus . They represent one or two migration events. Additionally, between 3.6 and 3.2 Ma, a single occurrence of Agriotherium insigne was recorded from the Weze 1 site. A few Early Pleistocene bear records are represented by U. etruscus , which was a probable ancestor of both arctoid and spelaeoid bear lineages. The oldest representative of Ursus ex gr. arctos known so far and assigned to U. a. suessenbornensis is known from one latest Early Pleistocene (1.2–0.9 Ma) locality, while other Polish records of this form require confirmation. The first occurrence of U. deningeri , the oldest taxon within the U . ex gr. deningeri–spelaeus lineage, was recorded from ~700 ka deposits in Silesia. During the pronounced cold period of MIS 12, the Scandinavian ice sheet covered almost the entire modern territory of Poland, with the exception of the Sudetes and the Carpathians. The accompanying drastic faunal turnover led to the formation of the pan-Eurasian Mammoth Fauna at ~460 ka. At that time a characteristic member of this fauna, the steppe brown bear Ursus arctos priscus , a specific ecomorph adapted to live in open grasslands, appeared in this region. It survived until the beginning of MIS 1, when modern Ursus arctos arctos appeared in Silesia and survived to the present day. U. deningeri was the most common bear during the Middle Pleistocene, while the first records of U. spelaeus spelaeus appeared since MIS 7. The latter form was replaced by U. ingressus during the Late Pleistocene (~110–100 ka). Spelaeoid bears totally dominated the cave assemblage, and finally vanished between 27 and 24 ka.

Fossil bear material from the lowermost deposits of the Jasna Strzegowska cave is described and its taxonomic status assessed. Comparison with bear remains from other Early and early Middle Pleistocene localities of Eurasia shows the presence of two bear species: Ursus etruscus and U. deningeri , based on morphological and size characters of the teeth and postcranial bones. The teeth of U. deningeri from the Jasna Strzegowska cave are larger, wider and have much more complicated occlusal surfaces when compared with the teeth of U. etruscus . Both bear species are characterized by relatively short and robust metapodials, although those of U. etruscus are on average less massive. Some differences in muscle attachments and articular surfaces have also been found. Metapodials of primitive arctoid bears, that co-occurred with U. etruscus and U. deningeri , are much longer and slimmer. U. etruscus and U. deningeri probably did not live in the Jasna Strzegowska cave at the same time. Based on its time range in Eurasia and morphological characteristics, the age of U. etruscus is estimated as Early Pleistocene, between 1.8–1.3 Ma. This is its first description from Poland, and the remains described are in size and morphology indistinguishable from material from other European localities. For U. deningeri , an early Middle Pleistocene age is suggested.

The Stajnia Cave is one of the most important archaeological sites due to the finds of the first remains of Neanderthals in Poland, and several tens of thousands of flint artefacts from the Middle Palaeolithic. Based on geological, geochemical, palaeobotanical, palaeozoological, archaeological and isotope analyses, coupled with absolute age determinations (OSL, U-Th and C 14 ), 15 lithostratigraphic layers were distinguished and palaeoenvironmental conditions during the sedimentation of these beds were determined. The cave loams accumulated through weathering, aeolian and fluvial processes. Their age may be correlated with an interval from the Early Glacial to the Late Pleniglacial of the Visulian (Weichselian) Glaciation. Archaeological relics related to the Neanderthals have been discovered in layer D with an absolute age of about 52,000–45,000 years BP and correlated with MIS 3 – the Middle Plenivistulian (Interplenivistulian). Climate oscillations in the Vistulian are reflected by the type of the sediments and their physical-chemical features, allowing determining warmer interstadial and colder stadial periods. Generally, the climate was cold, characteristic of tundra areas with a typical vegetation and fauna, and with the mean temperature of the warmest month not exceeding 12°C. Based on multi-proxy studies it can be concluded that from layer E1 upwards, the climate conditions became progressively drier. At that time, the climate was cold with continental features enhancing tundra domination. This conclusion is confirmed by palaeontological investigations and the record of stable oxygen isotopes in the teeth of reindeer. The studies have also indicated seasonal migration of reindeer on the tundra that surrounded the cave. Probably, short-term slight climate warmings occurred during the Middle Plenivistulian (Interplenivistulian).