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Studies on fossil bone microbial communities are scarce; even fewer studies were performed in cave deposits. For our research, sediments and fossil bones were sampled, and the whole community 16S rRNA gene-based metabarcoding analyses were performed on samples from Muierilor and Ursilor caves, some of Romania's most important archaeological and paleontological sites. Most of the identified taxa belong to Bacteria, with Proteobacteria, Acidobacteriota, Bacteroidota, and Actinobacteriota amongst the most abundant phyla in bone samples from both caves. The sediment samples presented similar composition, with Proteobacteria and Acidobacteriota being the most abundant phyla. The inferred bacteriomes indicated the presence of environment-specific bacteria, typical bone colonizers, and bacteria found in soils and decomposing human remains or archaeological profiles as well as phosphate-solubilizing and organotrophic bacteria. Diversity indices indicated a higher diversity in bone samples from Muierilor Cave than in Ursilor Cave samples and sediment samples from both caves. Environmental conditions, especially air relative humidity, were also considered in explaining the bacteriome diversity in different cave settings. These findings help to understand fossil bones' deposition and degradation in various environmental conditions. Furthermore, this is the first attempt to relate microenvironments and bacteria to preserving fossil bones from caves. [ABSTRACT FROM AUTHOR]

Bistriţa-Năsăud county from Romania has few remarcable caves. The most important is Tăuşoarelor cave, discovered in 1955 and placed third from the lenght point of view and the deepest cave in our country. It is located in Rodnei mountains, at 950 m altitude, near Rebrişoara village, having 20 km galleries lenght and 413.5 m depth. It contains cave bear bones, carstic formations, four underground rivers, a 15 m hight cascade and a specific fauna. It has only a scientific importance being closed for the mass tourism. Only specologists full equiped are allowed in the cave, but not more than 120 each year. [ABSTRACT FROM AUTHOR]

Research in cave bear palaeobiology focusing on population structure and mortality analysis may improve our understanding regarding the ecology of this species which vanished at the end of Marine Isotope Stage (MIS) 3, prior to Last Glacial Maximum (LGM), if assessed populations are large enough. Such population is available in Urşilor Cave, from north-western Romania, known as one of the most rich and complex European MIS3 cave bear sites. From the palaeontological excavation, situated at the lower level of the cave (= Scientific Reserve), more than 210 cave bear isolated lower molars, 160 mandibles and almost 180 canines were extracted and analyzed. The results obtained on the wear stages of the studied molars and mandibles indicated an "L"-shaped curve and suggest a non-attritional death pattern and a bone assemblage juvenile dominated. Moreover, the sex-ratio of upper and lower canines indicates a net dominance of females (5.4 females: 1 male). Although a "catastrophic" death pattern was obtained for cave bears, the animals seem to have died diachronically (non-simultaneously), over a time span of more than 6000 years. The triangular graph of age distribution is not appropriate for death assemblages from traps such as karst caves, where taphonomic processes like predation or scavenging would have played a less important role. [ABSTRACT FROM AUTHOR]

The most common methods used for assessing the relative age of a cave bear bone assemblage are the P4/4 index (morphodynamic index of the cave bear fourth premolar), the K-index, and the Index of Plumpness (both used for cave bear's 2nd metatarsal). Preliminary work on these indexes, for Urşilor Cave (NW Romania), has indicated one of the youngest European cave bear populations. As the number of extracted fossil bones from the palaeontological excavation increased recently, a re-assessment of the of the age of the cave bear assemblage is necessary. 206 cave bear fourth lower and upper premolars and 587 metapodials were analyzed. The P4/4 morphodynamic index, the K-index and the Index of Plumpness were calculated for the local MIS 3 cave bear bone assemblage. The results of the three indices have lower values when compared with the previously obtained for the same site and respect the subsequent radiometric ages (ca. 47-39 ky BP). However, the results for P4/4 morphodynamic index, K-index, and Index of Plumpness are of lesser relevance when used to assess the relative age of MIS 3 cave bear bone assemblages. All three methods require caution when applied and interpreted on short time intervals and on smaller geographic areas. [ABSTRACT FROM AUTHOR]

Urşilor Cave is one of the most complex MIS 3 cave bear settlements of Europe: it incorporates a large number of cave bears' palaeoichnofabrics ( bioglyphs : nests, footprints, scratch marks, fur imprints, etc.) and several bone assemblages of different age and genesis. This study has the aim of analyzing the spatial orientation and the internal architecture of the bone assemblage from the excavation chamber of the scientific reserve (lower level of the cave) in order to assess the environmental conditions of the bone deposition. As such, almost 580 long bones were analyzed for spatial orientation, and almost 100 plates of bone levels were documented at every 10 cm of depth (mapped, photographed and topographed). The obtained results point to an in situ thanatocoenosis (typical for cave traps) and reveal the taphonomic conditions at the time of the bone layers' deposition. Moreover, the taphonomic approach helped us to better understand the obtained radiocarbon data (on cave bear fossils)—which previously indicated a non-concordance with the stratigraphy—and to perform a taphonomic model for the bone’ deposition from the excavation chamber. Moreover, we report here the discovery of two fossil carnivore skeletons (a cave bear and a cave lion), one of the best preserved and anatomically connected, documented in such environments. [ABSTRACT FROM AUTHOR]

ABSTRACT In 1965, Ciur-Izbuc Cave in the Carpathian Mountains of Romania was discovered to contain about 400 ancient human footprints. At that time, researchers interpreted the footprints to be those of a man, woman and child who entered the cave by an opening which is now blocked but which was usable in antiquity. The age of the prints (≈10-15 ka BP) was based partly on their association with cave bear ( Ursus spelaeus) footprints and bones, and the belief that cave bears became extinct near the end of the last ice age. Since their discovery, the human and bear evidence and the cave itself have attracted spelunkers and other tourists, with the result that the ancient footprints are in danger of destruction by modern humans. In an effort to conserve the footprints and information about them and to reanalyze them with modern techiques, Ciur-Izbuc Cave was restudied in summer of 2012. Modern results are based on fewer than 25% of the originally described human footprints, the rest having been destroyed. It is impossible to confirm some of the original conclusions. The footprints do not cluster about three different sizes, and the number of individuals is estimated to be six or seven. Two cases of bears apparently overprinting humans help establish antiquity, and C-14 dates suggest a much greater age than originally thought. Unfortunately, insufficient footprints remain to measure movement variables such as stride length. However, detailed three-dimensional mapping of the footprints does allow a more precise description of human movements within the cave. Am J Phys Anthropol 155:128-135, 2014. © 2014 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

The Urşilor Cave (NW Romania) is a famous cave bear paleontological site hosting an important Late Pleistocene faunal assemblage and subject to systematic excavation works. To better understand the origin of fossil assemblages, the sedimentary history of the cave must be reconstructed. We conducted a series of investigations on various cave deposits which included sedimentology and grain-size analyses, U-series dating of speleothems, OSL dating of sediments, and AMS radiocarbon dating of fossil remains. The results allowed for the identification of several major chronological controls for the evolution of the cave during the last 300,000 years. Five evolutionary stages or key-moments were dated, and a tentative speleogenetic scenario is presented. The combined numerical dates and sedimentological study show that the evolution of the cave was more complex than previously thought. In particular, the fossil accumulation was related to a succession of rapid flooding events at ∼47-40 ka. Alternating depositional and erosional phases have occurred since at least 210 ka complicating the sediment structures. The results suggest that the upper and lower levels of the cave may have been functioned occasionally as hydrologically separated karst systems and that the animal populations from what is now a single cave system may not necessarily be synchronous. This case study shows that reconstructing sedimentary history of a given cave is crucial for the correct understanding of its thanatocenosis. [ABSTRACT FROM AUTHOR]

This paper presents a preliminary investigation of late Pleistocene cave bear traces from Ursilor Cave in the western Carpathians, Romania. The bears left thousands of traces on the walls, plateaus, and slopes of the cave interior. Some areas in the cave have been heavily trampled, leaving more than 140 hibernation beds as well as fur impressions. The footprints of cave bears are assigned to Ursichnus europaeus nov. ichnogen. and nov. ichnosp. and the cave bear-beds to Ursalveolus carpathicus nov. ichnogen. and nov. ichnosp. as behavioral traces. Tens of thousands of scratch marks on the slopes and top of a clay plateau are the result of bears moving from the hibernation area down to a stream and back. These traces reveal that the cave bears had short claws, similar to those of modern, primarily herbivorous black bears. Deep within the cave, three weathered, articulated cave bear skeletons still lie in their hibernation beds on the clay plateaus or a natural cave corner. One of these bears was a one-year-old male cub that did not survive its first hibernation; a second skeleton close was an adult female. The third, a young male, was found close to the end of the cave system. The bears of Ursilor Cave would have felt well protected against carnivores during their hibernation because their sleeping places were so deep within the cave. Their strategy may well have been to avoid any conflict with hyenas and lions during hibernation. [ABSTRACT FROM AUTHOR]

Previous bone collagen carbon and nitrogen isotopic studies of Late Pleistocene European cave bears (Ursus spelaeus) have shown that these bears frequently had low nitrogen isotope values, similar to those of herbivores and indicating either unusual physiology related to hibernation or a herbivorous diet. Isotopic analysis of animal bone from the Peştera cu Oase (Cave with Bones), Romania, shows that most of its cave bears had higher nitrogen isotope values than the associated herbivores and were, therefore, omnivorous. The Oase bears are securely identified as cave bears by both their morphology and DNA sequences. Although many cave bear populations may have behaved like herbivores, the Oase isotopic data demonstrate that cave bears were capable of altering their diets to become omnivores or even carnivores. These data therefore broaden the dietary profile of U. spelaeus and raise questions about the nature of the carnivore guild in Pleistocene Europe. [ABSTRACT FROM AUTHOR]

Stable isotope analyses provide one of the few means to evaluate diet of extinct taxa. However, interpreting isotope data from bone collagen of extinct animals based on isotopic patterns in different tissues of modern animal proxies is precarious. For example, three corrections are needed before making comparisons of recent hair and ancient bone collagen: calibration of carbon-13 variations in atmospheric CO2, different isotopic discrimination between diet-hair keratin and diet-bone collagen, and time averaging of bone collagen versus short-term record in hair keratin. Recently, Robu et al. [Isotopic evidence for dietary flexibility among European Late Pleistocene cave bears (Ursus spelaeus). Can J Zool. 2013;91:227-234] published an article comparing extant carbon (δ(13)C) and nitrogen (δ(15)N) stable isotopic data of European cave bear bone collagen with those of Yellowstone Park grizzly bear hair in order to test the prevailing assumption of a largely vegetarian diet among cave bears. The authors concluded that cave bears were carnivores. This work is unfortunately unfounded as the authors failed to consider the necessary corrections listed above. When these corrections are applied to the Romanian cave bears, these individuals can be then interpreted without involving consumption of high trophic-level food, and environmental changes are probably the reason for the unusual isotopic composition of these cave bears in comparison with other European cave bears, rather than a change of diet. We caution researchers to pay careful attention to these factors when interpreting feeding ecology of extinct fauna using stable isotope techniques.