1. INTRODUCTION Previously, biomechanical analyses have been widely applied in anthropology and primatology and sporadi- cally in the study of caviomorph rodents. Recently, because of the rich fossil record and contemporaneous presence of similarly designed, yet differently adapted forms, K U N S T (1996) applied biomechanical analyses on femora of Pleistocene European bears. Along with other skeletal traits, femoral cross-sectional shape was interpreted in Ursus spelaeus as being indicative of limb bone structure designed primarily for static stabili- ty. Therefore, the previous study of the cave bear limb bones from Croatian sites based on the variability of bone lengths, width of epiphysis and diaphysis (K R K- L E C , 1997; J A M B R E π I Ê et al., 2000) is now extended to the analysis of the inner structure, because the inter- nal bone structure yields some information on bone loading which can be analyzed and interpreted in bio- Osteometry, Variability, Biomechanics and Locomotion Pattern of the Cave Bear Limb Bones from Croatian Localities Gordana JAMBRE©I∆ and Maja PAUNOVI∆ mechanical terms. Thus, the aim of this paper is to test a hypothesis of convergent adaptation that was regis- tered on the metapodial bones from Mixnitz (S I V E R S , 1931). 2. MATERIAL AND METHODS The sample of 1328 limb bones of adult cave bears comprises 147 humeri, 392 radii, 218 ulnae, 160 femo- ra, 343 tibiae, and 58 fibulae originating from different Middle and Late Pleistocene levels (oxygen isotope stages 6-2) of the Vindija, Velika peÊina, and Veternica (NW Pannonian Croatia) and CerovaËke peÊine caves (E Central Croatia) (Table 1). The results are analysed together for each site because of the low statistical frequency of bones in stratigraphically different levels (Table 1). Different lengths and widths were measured after D R I E S C H (1976) and T S O U K A L A & G R A N D A L D ’ A N G L A D E (1997) with a digital calliper. The data obtained were compared and also used for computation of the robusticity index (Ir), representing the ratio of the mean value of the smallest diaphysis diameter and max- imal bone length, and bone index (BI) representing the Geologia Croatica 55/1 1 - 10 8 Figs. 5 Tabs. ZAGREB 2002 Key words: Cave bear, Limb bones, Rtg-osteometry, Variability, Biomechanics, Locomotion, Pleistoce- ne, Vindija, Velika peÊina, Veternica, CerovaËke peÊine, Croatia. Institute of Quternary Paleontology and Geology, Croatian Academy of Sciences and Arts, A. KovaËiÊa 5, HR-10000 Zagreb, Croatia; e-mail: goga@hazu.hr Abstract The estimated stylo- and zeugopodial bone index is lower for the cave bears from the mountainous region (CerovaËke peÊine caves) than the bone index from the hilly-lowlands caves (Vindija, Velika peÊina, Veternica) and indicates that limb loading depends on the body mass and palaeoenvironment. The type of movement was similar to the locomotion of the recent brown bear but with somewhat more expressed plantigrady on the hind limbs. At the same time, the sex ratio of the studied material depends firstly on the site morphology (endogene or exogene cave), i.e. its function (dense or periodically visited shelter), and also on geological processes and human activity. KljuËne rijeËi: spiljski medvjed, kosti udova, Rtg- osteometrija, varijabilnost, biomehanika, lokomo- torika, pleistocen, Vindija, Velika peÊina, Veternica, CerovaËke peÊine, Hrvatska. Saæetak Analize dugih kosti udova (stilopodija i zeugopodija) spiljskih med- vjeda iz pleistocenskih naslaga spilja Hrvatske pokazale su niæe vri- jednosti indeksa kostiju za medvjede koji su obitavali u visokogor- skom podruËju (CerovaËke peÊine) u usporedbi s medvjedima bre- æuljkastog tipa nalaziπta (Vindija, Velika peÊina, Veternica). Takvi rezultati dovode do zakljuËka da naËin optereÊenja udova ovisi kako o masi tijela tako i o okoliπu. NaËin kretanja spiljskih medvjeda sliËan je naËinu kretanja recentnih medvjeda s neπto jaËe izraæenom planti- gradnoπÊu straænjih ekstremiteta. Istodobno omjer spolova na obrae- nim lokalitetima prvenstveno ovisi o morfologiji terena i samog nalaziπta (egzogena ili endogena spilja), njegovoj funkciji (brlog ili povremeno skloniπte) te o geoloπkim procesima i ljudskoj aktivnosti. 2 Geologia Croatica 55/1 ratio of the mean value of the smallest diaphysis diame- ter and diaphyseal length. Diaphyseal length is the max- imal length of a central axis which is defined as passing through two reference points. These reference points are different for each bone: - femur (Fig. 1): proximal point lies on the superior face, in the middle between the femoral head and the greater trochanter, while the distal one is the most projecting point of the central trochlea; - humerus: proximal point is located on the caput humeri and the distal one on the condylus humerii between the trochlea humerii and capitulum humerii; - radius: proximal point is situated on the caput radii and distal one on the facies articularis carpea. Diaphyseal length of ulna, fibula and tibia c o r r e- spond to the maximal bone length. For selected bones from each site radiographs were taken with the aim of measuring outer diameter (D), inner diameter (M), lateral cortical thickness (CL), and medial cortical thickness (CM) at 50% of the diaphy- seal length from the distal end and perpendicular to the central axis (Fig. 1). These parameters have been used for calculation of the general cortical index (CI), medial cortical index (CIM), lateral cortical index (CIL) and cortical area (CA). CI=((CM+CL)/D)x100, CIM=(CM/D)x100, CIL=(CL/D)x100, CA=D2-M2 Data were analysed with “K-means clustering” and the “Hierarchical Joing (tree clustering)” method (ROHLF, 1992). To test our results, comparisons were made with rel- evant data obtained from the material of the Conturines, Herdengel, and Gamssulzen (REISINGER & HOHE- N E G G E R, 1998), Azé and Berzé (A R G A N T , 1 9 9 1 ) , Cova Eiros (GRANDAL D’ANGLADE, 1993) caves and 38 other caves from Spain (TORRES PEREZ- HIDALGO, 1988). 3. STRATIGRAPHY AND PALAEOGEOGRAPHY The present analysis was performed in order to try to confirm the hypothesis that the difference in morpholo- gy of the cave bear limb bones, opposite to the variabil- ity registered on the teeth, reflects distinct environmen- tal conditions and not different geological age. Namely, considering the age, the studied material was found in levels ranging from the OIS 7 or 6 to the OIS 2. Thus, Site Level humerus radius ulna femur tibia fibula Vindija E, F 8 36 17 8 21 G 17 67 26 13 30 H 3 40 15 4 58 I 9 9 5 12 J 4 27 30 7 50 K 27 4 24 L 7 35 11 13 46 M 1 3 1 Veternica d-j 29 36 33 27 39 11 CerovaËke c 62 62 63 67 52 13 Velika p. d, e, f 10 1 1 g, h, i 6 34 14 2 12 20 j, k 17 8 2 13 Table 1 Frequency of the limb bones found in Pleistocene levels of the Vin- dija, Veternica, CerovaËke peÊine and Velika peÊina caves. Fig. 1 Measuring points for radiograph analyses. for better understanding of the problem, the stratigra- phy of the investigated material must be reconsidered. The sample from the Vindija cave derives from deposits divided into 13 stratigraphic levels: the levels M and L appear to date to the OIS 7 or 6, unit K was previously correlated with the Eemian (OIS 5e), levels J-D encompass the Last Glacial (OIS 5d-2), while the upper three levels are Holocene (P A U N O V I ∆ et al., 2001). The cave bears from the Velika peÊina cave were found in level k (probably stadial phase of the Middle Würm), but also in levels j-i (interstadial phase of the Middle Würm), e-h (Late Würm), and d (Last Glacial Maximum). In the CerovaËke peÊine cave (P A U N O V I ∆ et al., 2001) only one fossiliferous level was registered and dated to the Last Glacial, i.e. to the OIS 3. Supported by palaeontological evidence the uppermost Pleistocene levels d and e from the Veterni- ca cave are ascribed to the OIS 2, and the levels f, g and h to the OIS 3 (PAUNOVI∆ et al., 2001). Also, the radiometrical data (Table 2) obtained from Croatian sites (WILD et al., 2001), as well as from Aus- trian and Italian caves (LEITNER-WILD & STEFFAN, 1993) show clearly the different ages of analysed popu- lations. At the same time, considering the geographical characteristics of the investigated sites, the analysed material was found in the caves belonging to: (1) the hilly-lowlands part of NW Pannonian Croatia (Vindija, Velika peÊina, Veternica) and (2) the Dinarides - moun- tainous part of E Central Croatia (CerovaËke peÊine). During the Last Glacial the northwestern part of Croatia was quite near to the ice cover of the Alps, while the northeastern area was part of huge steppe areas of the Pannonian Basin which featured a different vegetation, and was characterised by the dominance of sand steppe meadows, grassy steppes, riparian forests, and mixed deciduous and coniferous forests in the hilly regions. At 3JambreπiÊ & PaunoviÊ: Osteometry, Variability, Biomechanics and Locomotion Pattern... Cave Layer Age Method Vindija E 18,500 14C F/d/d 26,000 14C G1 28,020 AMS G1 29,080 AMS G1 27,010 U/Th G1 33,100 U/Th G1 33,000 AMS G3 41,000 U/Th G3 42,000 Amino acids G3 >42,000 AMS H 90,500 U/Th I/J 168,400 U/Th J 171,200 U/Th K 245,600 U/Th Velika peÊina e 26,450 14C g 31,168 14C i 33,850 14C Veternica c 13,660 14C i >43,200 14C CerovaËke c >40,000 14C Conturines Surface 17,900 U-series GSt4 44,500 U-series Spelaeothem under the bones >257,000 U-series Gamssulzen Fossiliferous layer 38,000 14C Fossiliferous layer 25,000 14C Fossiliferous layer 25,250 U-series Fossiliferous layer 27,250 U-series Herdengel Upper complex 37,000 14C Main fossiliferous layer 45,000 U-series Main fossiliferous layer 65,800 U-series Main fossiliferous layer 66,400 U-series Basal complex 126,900 U-series Basal complex 135,200 U-series Table 2 Radiometric dates from the Vin- dija, Velika peÊina, Veternica, Cero- vaËke peÊine, Conturines, Gamssul- zen and Herdengel caves (after W I L D et al., 2001, and L E I T N E R - WILD & STEFFAN, 1993). 4 Geologia Croatica 55/1 the same time, the Dinarides (as the southern extension of the Alps) played the role of a physiographic barrier between north and south. Although not glaciated today, they have supported isolated glaciers and were charac- terised by high mountain (?alpine) vegetation devel- oped on a karstic relief. Considering their palaeogeographical characteris- tics, i.e. the climate and altitude, the caves from Austria (Conturines, Gamssulzen, Herdengel), France (Azé, Berzé) and Spain also belong to these two main envi- ronmental types (Fig. 2). 4. RESULTS 4.1. Sexual dimorphism The first step in recognizing the problem of expressed sexual dimorphism registered among bears (P E R K I N S , 1973; STIRLING, 1993; REISINGER & HOHENEG- GER, 1998), required separation of the limb bones sam- ples into those representing males and females. The histograms and dendrograms (Fig. 3) showed a clear bimodal distribution for all bones - especially in the case of greatest and physiological length - in each site. Thus, the differences in sex ratio obtained by cluster analysis strengthen the clear differentiation into sexes obtained by univariate analyses. While in the investi- gated 6 limb bone elements from Velika peÊina the ratio is 73 : 61, in all other sites it is approximately 71 : 61. 4.2. Biometric analyses Because of the danger of allometric effects, i.e. size dependence of proportions which is especially relevant in materials representing variability in size and distribu- tions (sex ratio), the frequency distribution for each bone from each site was estimated (Fig. 4). It appears that all samples exhibit the same allometry, that the deviations from the regression are a result of modifica- tion, and that the single change deduced from the pre- sent data is size difference between geographically dif- ferent populations. The Hierarchical Joing (tree clustering) method showed the size variability of all limb elements, and a similar disposition for both sexes within the cluster of higher values for Vindija, Velika peÊina and Veternica, and the cluster of lower values for CerovaËke peÊine, Conturines, Herdengel and Gamssulzen (Fig. 5). A robusticity index, ratio of the mean value of smallest diaphysis diameter and maximal bone length, was calculated for both sexes together, by reason of comparison with relevant but unsexed data from some European localities. Calculated and compared robusticity index - Ir (Table 3) indicates the highest values for humeri (10.2- 11.7) and tibiae (10.6-12.5). The Ir of femora varies from 9.0 to 10.6, of radii from 7.5 to 11.0, of ulnae from 6.7 to 8.9, and of fibulae from 4.6 to 5.3. The strongest bones are the humerus and tibia. At the same time, the Ir of femora most probably indicates different types of locomotory and loading pattern: val- ues higher than 10.0 are registered among material from Veternica, Vindija, Velika peÊina and are similar to the indices from Azé, Berzé and the Iberian caves. On the other hand values lower than 10.0 are characteristic for bones from CerovaËke peÊine, Conturines, Herdengel and Gamssulzen (Fig. 6). Thus, biometric analyses, including robusticity index as an indicator of body size, show variability of the limb bones and the difference in body mass between geographically distinct populations of the cave bear. 4.3. Biomechanical and locomotory analysis The analysis consists of calculation and comparison of the bone index (BI), cortical index (CI) and cortical area (CA). Fig. 2 Absolute altitude (msl) of the studied caves. 5JambreπiÊ & PaunoviÊ: Osteometry, Variability, Biomechanics and Locomotion Pattern... Fig. 3 Examples of sex separation by K-means cluster- ing method. nlllA • VINDIJA 350 3IlD 250 200 1150 11)0 50 -<>- CIuRIr No. 1 """"'- " -- a....-N1I.2 B C D E F Gl H fI1IIIII8 VBr1IbIls TIBIA - VELIKA PECINA 350 300 250 200 150 100 50 --<>- Cluster No.1 females 0 ._.0-... Cluster No.2 A B C D E F G H males Variables TIBIA - VETERNICA 350 300 250 200 150 100 50 --<>- Cluster No.1 females 0 ... -0-... Cluster No.2 A B C D E F G H males Variables TIBIA - CEROVACKE PECINE 350 300 250 200 150 100 50 --<>- Cluster No. 1 females 0 .... 0-.- Cluster No.2 A B C D E F G H males Variables 6 Geologia Croatica 55/1 The bone index (BI) reflects the ratio between the mean value of the smallest diaphysis diameter and dia- physeal length. Unlike the maximal length (used in Ir), representing linear distance between two punctuate points on the epiphyses, diaphyseal length strictly con- note maximal length of a central axis and therefore rep- resent the length of the most laden part of the bone. Accordingly BI could indirectly reflect a type of bone loading. The estimated BI for CerovaËke peÊine and Con- turines, Herdengel and Gamssulzen caves are very sim- ilar, while the BI of the bears from the Veternica and Fig. 4 Example of distribution around intermediate regresion. Fig. 5 Example of size variability based on metric parameters for material from the caves Veterni- ca, Vindija, CerovaËke peÊine, Herdengel, Con- turines and Gamssulzen by Joing tree cluster- ing method. Fig. 6 Example for values of robusticity index (Ir) calculated for material from the caves Veterni- ca, Vindija, Velika peÊina, CerovaËke peÊine, Herdengel, Conturines and Gamssulzen, Azé, Berzé, Cova Eiros and Iberian caves. 7JambreπiÊ & PaunoviÊ: Osteometry, Variability, Biomechanics and Locomotion Pattern... Velika peÊina caves are higher, approximately 5-10% for males and 10-12% for females (Table 4, Fig. 7). Calculated general cortical index (CI), medial corti- cal index (CIM), lateral cortical index (CIL) and corti- cal area (CA), which also reflect the limb loading type, posture and locomotory pattern (Table 5), were exam- ined by the Hierarchical Joing (tree clustering) method. The dendrograms clearly show two main clusters con- humerus radius ulna femur tibia fibula Vindija 10.8 8.6 7.6 10.2 11.9 Velika peÊina 8.0 8.9 10.6 11.6 5.0 Veternica 10.4 7.5 7.8 9.9 11.7 4.6 CerovaËke 10.2 6.7 6.7 9.7 11.1 4.8 Conturines 10.2 6.8 7.3 9.6 11.1 Gamssulzen 10.6 7.0 7.4 9.8 11.1 Herdengel 10.3 6.9 7.5 9.8 11.3 Iberian caves 11.5 10.9 10.4 11.7 Aze . 10.5 10.0 9.9 11.6 4.3 Berze . 11.7 9.1 10.5 12.5 Cova Eiros 10.4 11.0 10.2 10.6 5.3 Table 3 Robusticity index (Ir) calculated for the material from the Veternica, Vindija, Velika peÊina, CerovaËke pe- Êine, Herdengel, Conturines, Gams- sulzen, Azé, Berzé, Cova Eiros and Iberian caves. humerus radius ulna femur tibia fibula Males Vindija 12.0 7.9 7.7 9.2 11.6 Velika peÊina 8.6 9.8 12.5 5.8 Veternica 12.0 8.2 9.2 9.5 12.0 5..5 CerovaËke 11.4 7.2 8.2 9.0 11.6 Conturines 11.6 7.9 8.7 9.1 11.4 Gamssulzen 11.3 7.9 8.6 8.8 10.9 Herdengel 11.4 8.0 8.9 9.0 11.5 Females Vindija 12.7 8.5 6.9 9.0 11.8 Velika peÊina 8.6 9.8 12.5 5.8 Veternica 12.3 8.0 8.6 9.0 12.1 5.4 CerovaËke 10.8 7.4 7.1 8.7 10.9 Conturines 11.3 7.2 8.1 8.7 11.1 Gamssulzen 11.6 7.6 7.9 8.7 11.3 Herdengel 10.7 7.0 7.2 8.6 11.3 Table 4 Bone index (BI) calculated for the material from the Veternica, Vin- dija, Velika peÊina, CerovaËke peÊi- ne, Herdengel, Conturines and Gam- ssulzen caves. Fig. 7 Example for values of bone index (BI) calcu- lated for material from the caves Veternica, Vin - dija, Velika peÊina, CerovaËke peÊine, Herden- gel, Conturines and Gamssulzen. 8 Geologia Croatica 55/1 Humerus 7 CA CAKa CI CIL CIM % Humerus 6 CA CI CIL CIM % Vindija 2816 53.3 28.3 25.0 11.6 Vindija 2541 60.0 30.9 29.0 6.1 Veternica 2573 50.8 29.8 24.5 17.8 Veternica 1525 55.8 30.2 27.9 7.6 2176 60.0 32.0 32.0 0 2400 54.5 29.0 25.4 12.4 CerovaËke 1365 48.8 27.9 20.9 25.1 CerovaËke 1071 45.0 22.5 20.0 11.1 1365 41.8 23.2 18.6 19.8 Recent Recent 522 41.3 17.2 24.1 28.6 Radius 7 CA CI CIL CIM % Radius 6 CA CI CIL CIM % Vindija 1113 56.7 29.7 27.0 9.1 Vindija 1008 48.6 27.0 21.6 20.0 1475 59.5 30.9 28.5 7.8 Velika peÊina 1276 55.0 30.0 25.5 17.0 Velika peÊina 616 48.2 27.5 20.6 25.0 1200 64.8 35.1 29.7 15.4 Veternica 1200 45.0 30.0 20.0 33.4 Veternica 800 48.4 27.2 21.2 22.0 1357 56.0 31.7 24.3 23.4 CerovaËke 1008 48.6 27.0 21.6 20.0 CerovaËke 440 37.0 22.2 14.8 33.3 960 58.8 35.2 23.5 33.3 Recent 731 42.8 36.6 20.0 45.4 Recent Ulna 7 CA CI CIL CIM % Ulna 6 CA CI CIL CIM % Vindija 864 63.6 33.3 27.2 9.0 Vindija 465 63.6 33.3 30.4 8.7 Velika peÊina 1525 58.1 30.2 30.3 7.6 Velika peÊina 1160 47.4 26.7 25.6 4.1 Veternica 1088 53.4 37.5 22.5 40.0 Veternica 825 42.8 25.7 17.1 33.4 1449 60.4 30.2 23.2 23.2 1365 52.3 23.8 23.8 0 CerovaËke 1056 60.0 31.4 28.5 9.2 CerovaËke 585 55.5 29.6 25.9 12.5 362 54.0 31.8 27.2 14.4 Recent Recent 528 53.3 25.0 17.8 28.8 Femur 7 CA CI CIL CIM % Femur 6 CA CI CIL CIM % Vindija 2059 58.0 28.0 30.0 6.6 Vindija 1375 62.5 30.0 32.5 7.6 1525 58.1 27.9 30.2 7.6 Velika peÊina 2241 49.0 23.6 25.4 7.0 Velika peÊina 2080 49.0 22.6 26.4 14.3 Veternica Veternica 1407 47.7 22.7 25.0 9.2 1452 51.1 22.7 27.2 16.5 1408 50.0 23.2 27.9 16.8 CerovaËke 1860 65.2 30.4 34.7 12.3 CerovaËke 1197 56.4 25.6 28.2 11.1 825 44.2 20.0 22.8 12.2 Recent Recent 473 38.3 18.5 22.2 16.6 Tibia 7 CA CI CIL CIM % Tibia 6 CA CI CIL CIM % Vindija 611 43.0 20.0 23.3 14.1 Vindija 1225 67.5 32.4 35.1 7.6 1045 54.3 24.3 27.0 10.0 Velika peÊina 1161 74.2 37.1 40.0 7.2 Velika peÊina 1121 48.7 23.0 25.6 10.1 945 63.6 30.3 33.3 9.0 Veternica Veternica 1710 60.0 28.8 31.1 7.3 1081 65.7 31.4 34.2 8.1 741 65.5 31.0 34.4 9.0 CerovaËke 1196 53.8 25.6 28.2 9.2 CerovaËke 633 60.7 28.5 32.1 11.2 800 63.6 21.2 27.2 22.0 Recent 319 60.0 25.0 30.0 16.6 Recent Table 5 General cortical index (CI), medial cortical index (CIM), lateral cortical index (CIL) and cortical area (CA) estimated for the cave bear long bones from the Veternica, Vindija, Velika peÊina, CerovaËke peÊine caves and the long bones of the recent brown bear. 9JambreπiÊ & PaunoviÊ: Osteometry, Variability, Biomechanics and Locomotion Pattern... sisting of males and females, and within each of them a disctinct sub-cluster of the CerovaËke peÊine cave (Fig. 8). The analysis of the CIM and CIL calculated for the cave bear bones and of CIM and CIL of the recent brown bear sample, shows that there is a difference in the loading pattern of limbs: on the forelimbs loading is stronger laterally, and medially on the hind limbs. But, there is no distinction between various populations of the cave bear as well as between these two species. 5. DISCUSSION Because the vertebrate body is defined by dimensions, weight, constitution, and proportions, its characteristics are closely related to the configuration, geometry and distribution of the mass, thus with inner mechanical forces deriving from the activity of the organism and/or caused by external forces connected with the environ- mental conditions (NIKOLI∆ & HUDEC, 1988). For example, performed anthropological studies (© E ∆ E- R O V , 1973) showed differences between the mountain and lowland populations expressed in the different width of the cortical bone and robusticity of the skeletal elements. These differences were explained with the subsistence and activity pattern of investigated human groups in different surroundings. The investigations of the human long bones were performed using, among other characteristics, the fact that the diaphyseal cross- section is non-homogeneous, and that the stress and tension is stronger on the outer contour of the bone than near the medullar cavity. Thus, using the actualistic theory, we have applied the same methods to study the biomechanical and loco- motory pattern of the fossil sample, especially because the cave bear was previously treated as a plantigrad ani- mal, and the obtained results showed a clearly different pattern of ecologically different populations. Therefore, if external mechanical forces depend on the activity of the organism, but in the first place reflect the ecological influences, the present study leads to the following conclusions: - The statement that large sized males are numerous at low altitudes, while females seem to be more abun- dant in higher regions (REISINGER & HOHENEG- G E R, 1998) must be reconsidered. Our oppinion is that the sex ratio of the cave bears depends in the first place on the site morphology (exogene or endogene cave), i.e. its function (dense or periodically visited shelter), geological processes and human activity. - The estimated bone index is lower for the material from the mountainous CerovaËke peÊine caves than the bone index for hilly-lowland sites Vindija, Velika peÊina and Veternica indicating that limb loading was caused by the smaller body mass, i.e. the type of movement was similar to the locomotion of the recent brown bear. - The RTG-osteometry of the studied bones showed the biggest difference in a cortical area (amount of cortical bone that is proportional to the axial rigidity, i.e. closely related to the body weight) indicating that the hilly-lowland forms from Vindija, Velika peÊina and Veternica were heavier and bigger and therefore featured clumsier locomotion. - Comparison of medial and lateral cortical indices of all samples leads to the conclusion that plantigrady (sensu D E N D A L E T C H E , 1986) described by P R A T & THIBAUT (1976) and C H A G N E A U (1986) is not a characteristic of the cave bears. From the obtained results it is obvious that the cave bear, similarly to the recent brown bears, was a semiplantigrad with some- what more expressed plantigrady on the hind limbs. Thus, because differences in biometry and biome- chanical characteristics between geologically older and younger populations were not registered, the obtained results confirmed only the discrepancy between the Fig. 8 Example of radiograph analysis performed on material from the caves Veternica, Vindija, Velika peÊina and CerovaËke peÊine by Joing tree clustering method. 10 Geologia Croatica 55/1 hilly-lowlands- and mountain-populations of the cave bear, and coinciding with the study of V I R A N T A (1994) indicated different limb loading and locomotory patterns. The smaller and more intensively movable forms (?cursorial) of the cave bear were adapted to harsher environmental conditions with insufficient food sources. 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