Carnivore impact on cave bear bones and the analysis of their dispersion. Case study: UrŞilor cave (NW Romania)

In taphonomy, the study of carnivore modification of fossil bones and the analysis of their dispersion represent the best approach to assessing the extent of bone modification and displacement for a given bone assemblage. Here we analyze the excavated bone deposit from Ursilor Cave, a well-documented and fossil-rich Upper Pleistocene cave bear site from the Romanian Carpathian Mountains. More than 1400 limb bones or bone remains were analyzed (NISPleft and right = 1424) and 69 measurable puncture marks were identified, measured and morphologically analyzed. Moreover, for assessing the degree of bone scattering, almost 540 cave bear limb bones and mandibles were refitted and the Index of Skeletal Disjunction (ISD) was calculated for the entire bone assemblage. More than 30 % of the analyzed cave bear limb bones were affected by carnivores: the ulnae were the most affected (39.3 %) while the humeri and femora were less modified (24.7 % and 25.5 %, respectively). The range of variation in size of the puncture marks, the morphological features of various tooth marks and the faunal composition of the studied bone assemblage indicate that at least two carnivore taxa are responsible for the bone modifications. The results obtained for the ISD index indicate higher displacement for femora when compared to other bones (e.g. tibiae, mandibles, humeri). Our analyses of bone modifications caused by carnivores indicate a low level of the scattering of intensely modified (by in situ consumption) bones, and notable carnivore impact on the configuration of the bone assemblage. Key words: Ursus spelaeus, taphonomy, ISD, tooth marks, Ursilor Cave, Romanian Carpathians. Vpliv zveri na kosti jamskih medvedov iz jame UrŞilor (SZ Romunija) in analiza njihove razkropljenosti Proucevanje sledov zveri na fosilnih kosteh in razkropljenosti kosti v prostoru je najboljse tafonomsko orodje za pridobivanje podatkov o obsegu taksnih pojavov znotraj posameznega paleontoloskega zbira. V raziskavi obravnavamo kosti jamskega medveda iz jame Ursilor, dobro raziskanega mlajsepleistocenskega najdisca v Romunskih Karpatih. Analizirali smo vec kot 1424 dolgih cevastih kosti okoncin ali njihovih odlomkov in pri tem prepoznali, izmerili in morfolosko analizirali 69 odtiskov zob. Poleg tega smo izracunali indeks razkropljenosti okostja (Index of Skeletal Disjunction, ISD) za celotni paleontoloski zbir, zaradi cesar smo sestavili skoraj 540 dolgih cevastih kosti okoncin in spodnjih celjustnic jamskega medveda. Sledove zveri smo prepoznali na vec kot 30 % kosti okoncin, najpogosteje na komolcnicah (39.3 %), nekoliko redkeje pa na nadlahtnicah in stegnenicah (24.7 % oz. 25.5 %). Variabilnost v velikosti odtiskov zob, njihovih morfoloskih znacilnostih in favnisticni sestavi proucevanega paleontoloskega zbira pricajo o tem, da sta ugotovljene spremembe medvedjih kosti povzrocili vsaj dve razlicni zveri. Vrednosti indeksa razkropljenosti okostja kažejo na izrazitejso razkropljenost stegnenic v primerjavi z drugimi kostmi (npr. golenicami, nadlahtnicami, spodnjimi celjustnicami). Nasa analiza kaže na skromno razkropljenost intenzivno obgrizenih kosti (zaradi hranjenja v sami jami) in znaten vpliv zveri na konfiguracijo paleontoloskega zbira. Kljucne besede: Ursus spelaeus, tafonomija, ISD, ugrizi, jama Ursilor, Romunski Karpati.