Pleistocene small cave bear (Ursus rossicus) from the South … · 2017. 12. 21. · tains Ursus rossicus, Panthera spelaea, Mammuthus aff. chosaricus, Equus aff. tauba - CAD. LAB

Cadernos Lab. Xeolóxico de LaxeCoruña. 2001. Vol. 26, pp. 373-398

ISSN: 0213-4497

Pleistocene small cave bear (Ursus rossicus)from the South Siberia, Russia

Un pequeño Oso de las Cavernas (Ursus rossicus)del Sur de Siberia, Rusia

BARYSHNIKOV, G.1, FORONOVA, I.2

A B S T R A C T

The skull, mandibles and cheek teeth of U. rossicus from four localities of the SouthSiberia are examined. This species inhabited the steppe regions in early Middle and LatePleistocene. By odontological characters it is more close to U. r. rossicus from Krasnodar,than to U. rossicus uralensis from Kizel Cave in Ural. Discriminant analysis, based onmeasurements of lower cheek teeth of the cave bears from seven sites of Europe andSiberia, demonstrated that U. rossicus most resembles morphometrically U. savini. As aresult of cladistic analysis employed 17 characters of skull, limb bones, and dentition, thephylogenetic tree has been obtained for 7 species of the genus U r s u s. A four species ofthe cave bears are included in the subgenus Spelearctos: U. savini, U. rossicus, U. denin -geri and U. spelaeus.

Key words: cave bears, U r s u s, Siberia, Pleistocene, evolution

(1) Zoological Institute, Russian Academy of Sciences, Universitetskaya naberezhnaya 1, 199034 St.Petersburg, Russia; e-mail: [email protected](2) Institute of Geology, Siberian Branch of Russian Academy of Sciences, pr. Akad. Koptiuga 3, 630090

Novosibirsk, Russia; e-mail: [email protected]

INTRODUCTION

Small cave bear Ursus rossicus Borissiak,1930 has been widely distributed inNorthern Eurasia in the Middle and LatePleistocene. In East Europe this specieswas found in the south of Ukraine,Northern Caucasus, Lower Volga River,Bolshoi Irgiz River basin, Ural River andin foothills of Ural Mountains(BORISSIAK, 1932, VERESHCHAGIN1959, 1982, K U Z M I N A, 1975,BARYSHNIKOV et al., 1991). It is alsoknown from the plain areas of Kazakhstan(KOJAMKULOVA, 1969). Two subspe-cies were distinguished: U. r. rossicus fromNorthern Caucasus (Krasnodar), LowerVolga (Kopanovka) and adjacent plains,and U. r. uralensis Vereshchagin, 1973from Kizel Cave and other cave localitiesof Middle and South Ural. The geographyof fossil findings points out that the smallcave bear was mainly a dweller of openherbaceous areas including the steppeones. It did not evidently penetrate toWest Europe where its remains are notrecorded.

In Siberia, N. Vereshchagin first iden-tified U . r o s s i c u s by os penis fromStrashnaya Cave in Altai(OKLADNIKOV et al., 1973). It was elu-cidated later that small cave bear was dis-tributed over the whole of South Siberia.It was recorded at Irtysh River (OmskRegion), Ob River (Krasnyi Yar), AltaiMountains (Strashnaya Cave, DenisovaCave), Kuznetsk Basin (Bachatsk andMochovsky quarries), Yenisei River(Kurtak) and in Transbaikalia (Tologoi onSelenga River) (A L E X E E VA, 1980;F O R O N O VA , 1982, 1999;

V E R E S H C H A G I N & T I K H O N O V,1994; B A RY S H N I K O V, 1995). Thesefindings are also associated with the zonesof spreading of the Pleistocene grass com-munities.

ALEXEEVA (1980), who gave briefcharacteristics of U. rossicus from KrasnyiYa r, came to the conclusion that theSiberian bear had been more specialized toconsume plants than other geographicraces. In the later paper she (ALEXEEVA,1996) proposed a new subspecies name U.rossicus obensis, but did not give a diagno-sis and did not designate the type, whichmakes this name not acceptible accordingto the Code of Zoological nomenclature.Vereshchagin & Tikhonov (1994) gave themap of findings of the small cave bear inSiberia. FORONOVA (1999, in press)published the photographs and brief mor-phological description of mandibles of U.rossicus from Kuzbass localities. The com-plete morphological analysis of theSiberian material is still absent.

This paper presents the first detaileddescription of skull fragments and teeth ofthe small cave bear from the collection ofZoological Institute Russian Academy ofSciences in Saint Petersburg (ZIN) andInstitute of Geology (IG), and Institute ofArchaeology and Ethnography (IAE),Siberian Branch of Russian Academy ofSciences in Novosibirsk.

MATERIAL AND METHODS

The material studied contains the skullfragment (ZIN 32748) and the right man-dible (ZIN 35075) from Krasnyi Yar inTomsk Province, the right mandible (IG328) from Bachatsk quarry (figure 1) and

374 BARYSHNIKOV & FORONOVA CAD. LAB. XEOL. LAXE 26 (2001)

the left mandible (IG 10128) fromMokhovo quarry (figure 2) in KemerovoProvince, 19 mandible fragments (IAE36, 63, 81, 88, 89, 93, 122, 171, 235,330, 331, 455 et al.) from Berezhekovo,Kurtak archeological region, KrasnoyarskTerritory (figure 3, 4), and also several iso-lated check teeth and limb bones fromthese localities. We have also used thephotograph of the skull from Kurtak,kindly provided by Dr. Nikolai Ovodov(Novosibirsk).

The material examined was comparedwith the collections of Ursus saviniAndrews from Bacton Forest Bed and U.deningeri von Reichenau from WestburyQuarry Cave, England (Natural HistoryMuseum, London) and Kudaro 1 Cave,Caucasus (ZIN), U. rossicus uralensis fromKizel Cave, Ural (ZIN), U. spelaeusRosemüller from Arcy-sur-Cure, France(Laboratoire díEthnologie prehistorique,Nanterre), from Odessa, Ukraine (ZIN

and University of Helsinki), and from theSecrets Cave, Ural Mountain (our data).

For the cranial characters analysis, weexamined also skulls of recent U. arctos L.and U. maritimus Phipps from ZIN collec-tion. We used the information on U. etrus -cus G.Cuvier published by MAZZA &RUSTIONI (1992). Additional data oncave bear was obtained from Andrews(1922), BORISSIAK (1932), RABEDER(1983), RABEDER & TSOUKALA(1990), M A Z Z A et al. (1995),Baryshnikov (1998), VERESHCHAGIN& BARYSHNIKOV (in press).

In the mode of measurements for skulland mandible we follow von denDRIESCH (1976). Cheek teeth were mea-sured following B A RY S H N I K O V(1998). Dimensions were taken with dialcalipers with accuracy up to 0.1 mm. Thedata were processed by Factor Analysis,Cluster Analysis and DiscriminantAnalysis from STATISTICA, 6.0. In

CAD. LAB. XEOL. LAXE 26 (2001) Pleistocene small cave Bear 375

Figure 1. Right mandible of Ursus rossicus from Bachatsk quarry, IG 328. Lateral view.

Discriminant Analysis, we used the for-ward stepwise method. PAUP computerprogram (version 3.1.1) was applied forthe phylogenetic analysis.

GEOLOGICAL SETTING ANDSTRATIGRAPHY

The studied material is originatedfrom the famous localities of the

Pleistocene mammal fauna in the south ofWestern and Middle Siberia: KuznetskBasin, Krasnyi Yar at the Ob River, andKurtak archaeological region.

The Kuznetsk Basin is situated in thesoutheast of the Western Siberia. It wasformed in the Late Cenozoic as an enor-mous intermountain depression, restrictedby the Kuznetsk Alatau, Gornaya Shoriya,and Salair Ridge. This region is one of the


Figure 2. Left mandible of Ursus rossicus from Mokhovo quarry, IG 10128. Lateral view.

Figure 3. Fragment of right mandible Ursus rossicus from Berezhekovo 4, IAE 171. Occlusal view.

most biostratigraphically important in thenon-glacial zone of Northern Asia. ThickQuaternary sediments (seven alternatedsub aerial and sub aquatic formations)with a great number of fossil bone remainsuncovered in opencast coalmines. Morethan 60 taxa of the carnivores, probosci-des, perissodactyls and artiodactyls ofvarious geological age were recorded here,allowing reconstruction of the faunal his-tory in the south of Western Siberia fromthe Early Pleistocene to Holocene, to tracephylogenetic lines in basic mammaliangroups, and also to elucidate the successi-ve stages of their evolution(FORONOVA, 1982, 1986, 1998, 1999,in press).

The bear remains (mandibles and pos-tcranial elements) have been recorded inthe Kuznetsk Basin in situ at differentstratigraphical levels. The mandible IG328 of Ursus rossicus was found inLatyshovo levels of Kedrovka Formationin Bachatsk quarry. Kedrovka Formationrepresents bluish-gray loam and clay, plas-tic, flaky, with wood debris, basal shingle

and hydromorphic fossil soils. These depo-sits mainly have lacustrine-alluvial gene-sis, fill the pits in lower layers and reachthe thickness of 45 m. In Kuznetsk Basin,Kedrovka Formation is associated withthe most of Pleistocene large mammalsremains. In the morphology and ecologi-cal peculiarities, recorded species fromlower and upper levels of this formationbelong to the different faunistic comple-xes.

In the basal part, represented by theKrasnogorsk Member, the fossil remainscontain Gulo cf. schlosseri, Mammuthus tro -gontherii (corresponding in its morphome-trical data to those of this species fromSüßenborn locality in Germany), Equusmosbachensis, Rangifer sp., and a very largebison, Bison aff. priscus. This fauna is corre-lated with the Tiraspolian and Viatkianfaunas in East Europe and West Siberiaand the Cromerian faunas of We s t e r nEurope.

The overlying Latyshevo Member con-tains Ursus rossicus, Panthera spelaea,Mammuthus aff. chosaricus, Equus aff. tauba -


Figure 4. Left mandible of juvenal Ursus rossicus from Berezhekovo, IAE 268. Occlusal view.

chensis, E. ex gr. mosbachensis-germanicus,Coelodonta antiquitatis, Cervus elaphus,Megaloceros giganteus, Bison priscus. Theteeth of M. aff. chosaricus, in comparisonwith its ancestor M. trogontherii, differ inless enamel thickness, the length of platesand larger plate frequency. Generally, thespecies composition and evolutionary levelof the fauna representatives correspond tothe Holstein, which conform to Tobolinterglacial in Western Siberia.

The mandible IG 10128 was found inthe sediments of Krasnobrodsk Formationin Mokhovo quarry. These are lacustrine-alluvial loam with ferruginous shingle atits base and cryoturbations and frost-wedge casts in its upper part.Accompanied fauna is represented byremains of Vulpes vulpes, Panthera spelaea,Equus przewalskii, Equus ex gr. gallicus,Equus aff. hydruntinus, Coelodonta antiquita -tis, Cervus elaphus, Megaloceros giganteus,Alces alces , Rangifer tarandus , Bison priscus ,S a i g a sp., and Mammuthus primigenius.Both thin and thick-enamel variations ofmammoth teeth can be distinguished. Thefirst group may correspond to the begin-ning of the Weichselian, while the secondone having the radiocarbon dates 39.1,31.9 and 28.9 thousand years belongs tothe Middle Weichselian (Karginsk) war-ming. Creating of these formations finis-hes apparently in the Late Weichseliancooling, as evidenced by cryoturbationfeatures in the uppermost part of thesequence.

The locality Krasnyi Yar that is theplace of finding the skull ZIN 32748 andmandible ZIN 35075, is situated 0 t ObRiver in Tomsk Province. A lot of boneshave been gathered over several years on

the riverbank. These were not associatedwith geological layers, but mainly origi-nated from the Middle and LatePleistocene levels. The degree of conserva-tion of the bones allows suggesting thatthe main part of the bone assemblage hadbeen formed in the Later Pleistocene.Castor fiber, Canis cf. lupus, Ursus cf. denin -geri (large form), Crocuta spelaea, Pantheraspelaea, Equus caballus subsp., E. cf. prze -walskii, E. hemionus, Dicerorehinus kirchber -g e n s i s, Coelodonta antiqutatis, M e g a l o c e r o sgiganteus, Cervus elaphus, Alces alces, Bisonpriscus, Saiga borealis were recorded here(ALEXEEVA, 1980).

Kurtak archaeological region is situa-ted in the south of Middle Siberia, in theNorthern Minusinsk Basin. The sites werediscovered after the flooding of the YeniseiRiver valley and forming of KrasnoyarskReservoir. The thickest Quaternary sedi-ments of various origins are exposed in theleft riverbank, at Berezhekovo sites. Thereare opened here the ancient alluvial depo-sits of high Yenisei terraces, colluvial for-mations (filling of the former ravines cut-ting through terraces), and covering,mainly eolian loess-like loams and sandyloams, containing several paleosoil hori-zons. At the present time these sectionshave been examined geologically, archaeo-logically, and paleontologically, and ther-moluminescent and radiocarbon data havebeen obtained (DROZDOV, et al. 1990a,1992; DROZDOV, et al. 1990b). Thebear remains described in this study, havebeen found at the Berezhekovo 2,3 and 4sites in the Middle and Late Quaternaryeroded brown loams, in the basement ofsection, and on the river beach. Therewere found remains (determineted by


I.Foronova) of Canidae gen. indet.,H o m o t h e r i u m sp., Panthera spelaea,Mammuthus primigenius, Mammuthus sp.,Equus sp. (large form), Equus aff. hydrunti -nus, Equus cf. przewalskii, Coelodonta anti -quitatis, Cervus elaphus, Megaloceros gigan -teus, Alces alces, Rangifer tarandus, Capreoluscapreolus, Ovis cf. ammon, Bos sp., Bison pris -cus. The mandible IAE 36 was recorded inBerezhekovo 2, IAE 1681 in Berezhekovo4, IAE 93, 330, 331, 455 in Berezhekovo3-4. These localities are also associatedwith the Middle and Late Pleistocenesmall mammals fauna (KRUKOVER &CHEKHA, 1999).

DESCRIPTION

Skull

The skull of the bear from Krasnyi Yar(ZIN 32748) has only the facial portion.Cheek teeth are heavily worn. Their occlu-sal surface nearly lost enamel, demonstra-ting the patches of dentine. Small size andslender canines (length at enamel border16.3 mm, width 12.7 mm) indicate thisspecimen as an old female.

Frontal bones are convex, abruptly rai-sed over the nasal bones. The postorbitalprocess is short but broad and blunt.Orbits are placed closer than minimumbreath between orbits in the nominativesubspecies from Krasnodar (BORISSIAK,1932). The orbit is comparatively large(greatest diameter 52 mm) and directed inits upper portion more anterior than in U.arctos (ALEXEEVA, 1980). There are twolacrimal foramina approximately equal insize. The anterior root of the zygomatic

arch is thickened; its height equal to 40mm. The infraorbital foramen is small,situated over the posterior part of 1.Nasal bones are short, narrow, in anteriorhalf being parallel to the palate. Theiranterior end is finished at the level of 4.Nasal aperture is large, nearly as high asbroad. The palate is comparatively broad.Its breadth increases greatly in front of theanterior border of 4 (68.3 mm) to thecanine alveoli (89 mm). The distance bet-ween medial margins of the latter exceedsthat between 2, resembling in this featu-re the specimens from Krasnodar(BORISSIAK, 1932). The length of inci-sors row is 62.4 mm. The anterior premo-lars P1-3 are absent; ALEXEEVA (1980)mistakenly considered the alveolus of P3as an anterior alveolus of P4. The length ofpost canine diastema is 38.5 mm. The dis-tance from the level of P4 anterior marginto I1 alveolus is somewhat shorter thanthe length of P4-M2.

This specimen is peculiar in a ratherposterior position of incisive foramina,which exceed beyond the level of posterioredges of canines. This is not characteristicfor the cave bears and is probably causedby the very old age of the individual.

The skull ZIN 32748 in its size andmorphology is similar to those of U. rossi -c u s from Krasnodar and Kizel Cave(BORISSIAK, 1932, VERESHCHAGIN& BARYSHNIKOV, in press).

Measurements (mm): "snout" length -138, length C1-M2 - 137.5, length P4-M2 - 79.6, least breadth between theorbits - 74.6, greatest palatal breadth - 84,breadth at the canine alveoli - 89, breadthbetween for. infraorbitale - 73.8, greatestbreath of nasal opening - 57.6.


The skull from Berezhekovo is com-pressed and belongs to the young indivi-dual. The palatine between posteriormolars is narrow. The anterior premolarsare absent.

Mandible

Most specimens have worn to heavilyworn cheek teeth. In Berezhekovo, onlythree of 19 mandible fragments studiedmay be attributed to young animals. Thespecimen from Mokhovo quarry alsobelonged to a young bear.

Males of U. rossicus were probablymuch larger than females(VERESHCHAGIN & BARYSHNIKOV,in press), sexual dimorphism is shownmainly in the canine size. In the materialinvestigated, three mandibles were attri-buted to males due to their greater totallength and width of the lower canine(table 1, 2).

Mandibles demonstrate structure and

size common to U. rossicus. Anterior pre-molars p1-p3 are absent, the length ofdiastema changes from 34.5 to 46 mm.The body of the mandible is high; the lineof its inferior border is curved. The heightof the body is considerably decreasinganteriorly, reaching its minimum at thediastema. The angular process rising, thecondylar process is situated at the level ofarticular surface. There are two mentalforamina, the posterior one being largerand situating below p4, and sometimes itis divided in several small openings.

By the total size and the length of thedental row, the samples from Siberia arevery similar to those of U. rossicus fromKrasnodar (BORISSIAK, 1932) and fromKizel Cave (table 3). They are somewhatsmaller on average than mandibles of U.savini from Forest Bed, but this differenceis not statistically reliable.

Factor analysis has been carried out for11 measurements of male mandibles. Theresults are shown in the figures 5, 6 and in


Table 1. Sizes of mandibles in males of Ursus rossicus from the South Siberia.

table 4. In plote of the Factor 1 (c1-m3length, m2 length, m2 width) and Factor2 (m1 length), the samples are divided intwo groups. The first one comprises U.savini from Forest Bed and U. deningerifrom Kudaro 1 Cave; the second containsU. rossicus from Siberia localities and fromKizel Cave (figure 5). In space of theFactor 2 and Factor 3 (p4-m3 length, m1width), the sample of U. deningeri appea-red to be separated from others (figure 6).Despite the fact that we dealt with arather small collection, we can suggest a

morphometrical resemblance not onlybetween the U. rossicus from Siberia andfrom Ural, but also the similarity of thissmall cave bear with U. savini.

Dentition

Upper teeth. Upper cheek teeth ofthe skull ZIN 32748 are heavily worn andare not suitable for a morphological analy-sis. Therefore only M2 has been measuredin this specimen. Additionally, three sam-ples of this tooth with obliterated occlusal


Table 2. Sizes of mandibles in females of Ursus rossicus from the South Siberia.

Table 3. Comparison of mandibles in Ursus rossicus.

surface were recorded in Berezhekovo. Ona Berezhekovo skull, judging from photo-graph, the upper molars bear numerousadditional tubercles.

M2. The greatest length and width ofthis tooth is correspondent to those in U.rossicus from Krasnodar and Kizel Cave

(table 5). The paracone is large, with ablunt top. One specimen demonstrates thelack of the additional tubercle in front ofthe paracone, which is represented on theteeth from Krasnodar (B O R I S S I A K,1932) and is commonly present in U. spe -laeus. The metacone is undivided, conside-


Figure 5. Plot of factor scores of Factor 1 and Factor 2 from principal component analysis of man-dibles. d- Ursus deningeri , Kudaro 1 Cave; f- U. savini , Bacton Forest Bed; k- U. rossicus , SouthSiberia; z- U. rossicus, Kizel Cave.

Figure 6. Plot of factor scores of Factor 2 and Factor 3 from principal component analysis of man-dibles. The symbols are as in figure 4.

rably smaller than the paracone, and itsapex is moved anteriorly. The row of lin-gual tubercles in all specimens is heavilyworn. In U. savini, this tooth is on avera-ge somewhat shorter and narrower, and inU. deningeri from Westbury, it is, on thecontrary, longer and wider, but in bothcases the differences are not statisticallyreliable. It differs more noticeably withthat of M2 in U. spelaeus from Odessa,where it is apparently larg e r(BARYSHNIKOV, 1998).

Lower teeth. The lower cheek teethare more numerous; all of them were retai-ned in mandibles and show the variousdegrees of crown abrasion. Relative valuesof the average length for p4, m1, m2 andm3 are 16,3-27,7-29,1-26,9%. For thisindex, the small cave bear from Siberia issimilar to U. rossicus from Kizel Cave andKrasnodar, although the former has relati-vely longer m1 (29,1%). All the cavebears show m1 on average is shorter thanm2, with exception for U. savini, having


Table 4. Correlations of characters with the first three principal components for mandibles.

Table 5. Comparison of cheek teeth in Ursus rossicus.

in contrary m1 longer than m2 (a primiti-ve character inherited from U. etruscus).

p4. The crown is of the equal width inthe anterior and posterior parts. The pro-toconid is high, blunt-pointed, andwithout crests. Its base bears two largeadjacent cusps on the lingual side (paraco-nid and metaconid), these sometimesbeing linked with a small denticle (figure7, 8). The paraconid commonly extends infront of the protoconid. A slender ridgeruns from the metaconid posteriorly. Theposterior tooth part is abruptly bent back-ward, without additional tubercles, whichare recorded in the Krasnodar specimens(BORISSIAK, 1932). There are two well-separated roots.

The multiple discriminant functionanalysis based on three measurements(greatest length, greatest width, and dis-tance between paraconid and metaconidtips) was carried our for six samples: U.savini (n=10), U. deningeri (n=8), U. rossi -

cus, Siberia (n=5), U. spelaeus from Arcy-sur-Cure (n=41), from Odessa (n=40), andfrom Secrets Cave (n=13). The results ofthis analysis are present in figure 9, whichshows the centroid of each group plottedonto the first two canonical variates. A lit-tle over 85% of dental variation is explai-ned by the first canonical axis, 13% by thesecond. The first canonical variate discri-minates greatest width, on the secondcanonical variate including greatestlength (table 6). The bivariate plot of cen-troids clearly shows an ordination into 2separate groups, with savini/deningerisamples on the one hand and all the othersamples on the other. SquaredMahalanobis distances between membersof these groups are high (from 5.59 to14.5). In the second group, which con-tains U. rossicus from Siberia, the distancesare lower (less than 3.87). The Siberiansample shows statistically reliable diffe-rences only from U. deningeri (p


Figure 8. Lower cheek teeth p4 (a-d) and m1 (e-g) of Ursus rossicus from South Siberia. Lingualview. a-c, e-f - Berezhekovo, d- Bachatsk, g-Mokhovo.

Figure 9. Plot of centroids for each locality on the plane canonical variate 1 and 2 for p4.

Table 6. Correlations of canonical variate for p4.

Based on the results of this analysis, wemay conclude that p4 proportions in U.rossicus are similar to those of U. spelaeus,being different with those U. savini, andmore sufficiently from U. deningeri.

Among teeth of U. rossicus studied, themean of the greatest length is at a maxi-mum in Krasnodar and minimum inKizel Cave (table 5), and the differencesbetween them are reliable for this measu-rement (p

samples with the exception of U. rossicusfrom Siberia/U. savini . Thus the m1 pro-portions among U. rossicus are rather diffe-rent, but demonstrate more resemblancewith those in U. savini, than with othercave bears (in the least degree with U. spe -laeus).

In the samples of U. rossicus, the lon-gest m1 has been recorded in Kizel Cave(table 5), however its differences in thismeasurement with Siberian andKrasnodar specimens are not statisticallyreliable.

In U. spelaeus, the crown is mostnarrow at the trigonid and talonid junc-tion but in U. rossicus, U. savini and U.

deningeri, this place is approximately aswide as trigonid. U. etruscus, U. maritimusand U. arctos show the complicated meta-conid and entoconid, the latter consistingof one or two cusps. Cave bears demons-trate a trend toward further developmentof entoconid portion. In U. rossicus, U.savini and U. deningeri, it is formed by twoor three adjacent tubercles, while in U.spelaeus the entoconid more often has ashape of two large well-separated tuber-cles of almost equal height. Thus, U. rossi -cus demonstrates a rather primitive m1structure.

m2. This tooth is rectangular in shape,with talonid wider than trigonid. The


Table 7. Correlations of canonical variate for m1.

Figure 10. Plot of centroids for each locality on the plane canonical variate 1 and 2 for m1.

protoconid is undivided, situating belowthe metaconid. The latter is divided intwo or three nearly equal cusps, the mid-dle one being the longest. This tubercle isnot moved medially, which often takesplace in U. spelaeus. The hypoconid iswider than the entoconid. The latter islonger than hypoconid and consists of twol a rge and well-separated tubercles.Sometimes an additional denticle betweenthe metaconid and the entoconid occurs.

The discriminant analysis based onseven measurements (greatest length,labial length of trigonid, lingual length oftrigonid, labial length of talonid, linguallength of talonid, width of trigonid, andwidth of talonid) was carried out for sevensamples: U. savini (n=11), U. deningeri(n=31), U. rossicus from Siberia (n=9) andfrom Kizel Cave (n=13), U. spelaeus fromA r c y - s u r-Cure (n=43), from Odessa(n=37), and from Secrets Cave (n=8). Theresults of this analysis are presented infigure 11. More than 76% of dental varia-tion is explained by the first canonicalaxis, 11% by the second. The first canoni-cal variate discriminates labial length oftalonid, greatest length and width of tri-gonid, on the second axis lingual length oftalonid contributes to discrimination(table 8). The plot of centroids demonstra-te an ordination into 3 separate groups: 1)U. savini and U. rossicus, 2) U. deningeri,and 3) U. spelaeus. Squared Mahalanobisdistances between the first and secondgroups (from 2.95 to 6.74) are approxima-tely the same to those between the secondand third ones (from 4.57 to 8.94). In thefirst group, both samples of U. rossicussituate more close with one another(Mahalanobis distance 1.75), than to that

of U. savini (5.76, 5.81). Statistically relia-ble distances (p

The discriminant analysis based onfour measurements (greatest length,length of talonid, greatest width, andwidth of talonid) was carried out for sixsamples: U. savini (n=11), U. deningeri(n=47), U. rossicus, Siberia (n=6), U. spe -laeus from Arcy-sur-Cure (n=41), fromOdessa (n=42), and from Secrets Cave(n=8). The results of this analysis are pre-sented in figure 12. Nearly 74% of dentalvariation is explained by the first canoni-cal axis, almost 16% by the second. Thefirst canonical variate discriminates inclu-des all measurements (table 9). The plot ofcentroids clearly shows an ordination into2 separate groups, with all samples of U.

spelaeus on the one hand and all the otherexamined samples on the other. SquaredMahalanobis distances between samples ofthese groups are rather low (from 2.59 to5.06). In the first group, all the samplesdistribute very close to one another(Mahalanobis distances from 0.16 to1.65). Differences between the samples ofU. rossicus and U. spelaeus are statisticallyreliable (p

demonstrates the largest m3 in three sam-ples examined of U. rossicus (table 5), onlythe specimens from Krasnodar and KizelCave reliably differ in the greatest crownwidth (P

ples from Siberia and Krasnodar constitu-te one cluster, while the sample fromKizel Cave groups with that of U. savini.

The obtained results of the discrimi-nant analysis show the resemblance of U.rossicus with U. savini in proportions of thelower molars m1, m2 and m3. However inproportions of the lower premolar p4, theformer species is more close to U. spelaeus.The enlargement and complication of p4may be treated as a specialization of U. ros -sicus to consume rough herbaceous food.

Postcranial skeleton

The isolated limb bones of a smallcave bear have been found in Mokhovoquarry and in Berezhekovo. To identifytheir sex we used the data on the size sexdimorphism in U. rossicus , established forthe sample from Kizel Cave (see

VERESHCHAGIN & BARYSHNIKOVin press). The specimens examined resem-ble in size the corresponding bones fromKizel Cave (table 10). The single fourthmetacarpal, unlike those from Kizel Cave,does not have the incision on the distalarticulate ridge.

CLADISTIC ANALYSIS OF CAVEBEARS

The subgenus Speleartos E.Geoffroy,1833 includes four species: U. saviniAndrews, 1922 (early MiddlePleistocene), U. deningeri von Reichenau,1904 (Middle and Late Pleistocene), U.rossicus Borissiak, 1930 (Middle and LatePleistocene) and U. spelaeus Rosenmüller,1794 (late Middle and Late Pleistocene).The first and fourth species are found inEurope only, the both others are found in


Figure 13. Similarity dendrogram of samples of genus Ursus based on length and width means oflower cheek teeth p4, m1, m2 and m3.

the many localities of the NorthernEurasia.

We scored seven ursid taxa and 17 cha-racters of skull, cheek teeth, limb bones,and body size (see table 00). We used U.etruscus G.Cuvier, 1823 as an outgroup.This species is considered to be ancestralboth for the cave bears and the recent spe-cies of the genus Ursus (U. arctos and U.m a r i t i m u s) (E R D B R I N K, 1953,KURTÉN, 1968).

Characters. 1. Frontal profile: gentle(0), steep, so the frontal bones are stronglyraised over the nasal bones (1).

2. Nasal bones: long, terminatinganteriorly over the posterior edge of theupper canine (0), short, the anterior endsituated over 4 (1).

3. Condylar process: lies at the levelwith the occlusal surface of the lowercheek teeth (0), elevated higher than thelevel of the latter (1).

4. Body of the mandible: relativelylow, its inferior border being straight (0),high, and the inferior border is curved,forming a prominence under m2 (1).

5. Entepicondylar foramen of humerus:present (0), absent (1). Among recentbears this foramen is observed in primiti-ve Ailuropoda and Tremarctos, and is absentin the representatives of all other genera.In U. etruscus, this feature varies (MAZZA& RUSTIONI, 1992).

6. Metacarpal and metatarsal bones:short (0), relatively long (1).

7. Ridge of the distal articulate surfaceon metacarpal and metatarsal bones:round, without incision (0), with smallincision on the distal border (1).

8. Premolars P2-3/p2-3: present com-pletely (0), present partly (1), absent (2).

9. Anterior premolars P1/p1: present(0), absent (1).

10. Protocone of P4: simple (0), subdi-


Table 10. Sizes of limb bones in Ursus rossicus from South Siberia.

vided or associated with additional tuber-cles (1).

11. Medial wall of the metacone P4:without tubercle and enamel fold (0),those present (1).

12. Talon of M2: short and relativelynarrow (0), long and moderately wide (1),long and very wide, its inner field withlarge rugae (2). The genus Ursus is charac-terized by the elongation of 2 talon,which is secondary reduced in U. martimus(MAZZA, et al. 1995).

13. Lower carnassial tooth m1: large,longer than m2 (0), slender, shorter thanm2 (1).

14. Lower premolar p4: simple (0),complicated with labial cusps (paraconidand metaconid) (1), complicated withlabial cusps and additional tubercles (2).

15. Endoconid of m1: usually with asingle tip (0), with two tips or comb-sha-ped (1).

16. Talonid of m3: not developed (0),wide, separated from trigonid (1).

17. Body size: medium or small (0),large (1).

Results. The data matrix was run byheuristic search option of PAUP and onetree was produced (TL=23, CI=0.826,RI=0.852). A parsimony analysis resultedin the phylogenetic hypothesis shown infigure 14.

Among the selected features of thegroup U r s u s a r c t o s / m a r i t i m u s p l u sSpelearctos character 5 are here consideredequivocal, but character 8(1) is consideredan unambiguous synapomorphy. Bothpeculiarities separate this group from pri-mitive ursids.

Monophyly of the subgenus Spelearctosis supported by 12 synapomorphies. These

confirm the distinct taxonomic status ofthis subgenus. Peculiarity of the cavebears is caused by the high rate of theirmorphological evolution, and mainly bychanges of their masticatory system, pro-voked by transition from omnivorous tochiefly vegetable diet.

Relationships within S p e l e a r c t o s a r edetermined by two synapomorphies (cha-racters 14(2) and 3). These indicate thefurther specialization of the cave bears tovarious plant food.

The obtained phylogenetic tree gene-rally agrees with the data on the sequenceof cave bear species appearance in the geo-logical record. U. spelaeus, for example,seems to be not only the most advancedbut also the youngest among them.

DISCUSSION

Our investigation confirms that U. ros -sicus was widespread in South Siberia inMiddle and Late Pleistocene. In propor-tions of the cheek teeth, the Siberian bearis more similar to the nominative subspe-cies than to U. rossicus uralensis. Therefore,the range of the nominative taxon inclu-ded the steppe zone from Ukraine to theNorthern Caucasus in the west toKazakhstan and south of Middle Siberia inthe east. The specimens from the Middleand Late Pleistocene do not show suffi-cient differences, possibly the former aresomewhat larger.

BORISSIAK (1932: 190) suggested U.rossicus was a steppe race of the cave bear,which had more progressive dental struc-tures than in U. spelaeus from Europe.However, archaic characters of its denti-tion allow him to treat these bears as a


parallel branch, originating from the com-mon ancestor.

The obtained results partly support theBorissiak opinion. U. rossicus has a specia-lized lower premolar p4. The trend tocomplication of this tooth among cavebears is demonstrating by U. savini (seeANDREWS, 1922), reaches its greatestdevelopment in U. rossicus and U. spelaeus.U. deningeri, in contrast, demonstratessimplification of p4. The morphology ofthe other lower cheek teeth in U. rossicus israther primitive and consequently, the

level of differentiation of its dentitiondoes not exceed that in U. savini/deningeri.

Judging by material examined, publis-hed data (B O R I S S I A K , 1 9 3 2 ,VERESHCHAGIN & BARYSHNIKOV,2000), and distribution, we can imaginethat U. rossicus was a small bear of 1.5 min length and 0.8 m in height in scapulararea. It seems to have been relatively slug-gish and fed mainly on the vegetativeparts of plants, roots, berries, fruits, andoccasionally invertebrates, smaller verte-brates, and carrion. This bear inhabitedthe open landscapes of plains and lower


Figure 14. Proposed phylogenetic hypothesisfor the genus Ursus according to either accele-rated (ACCTRAN) optimization (L=23,CI=0.826, RI=0.852). See text for the descrip-tion of inferred synapomorphies 1-17.Character matrix is in table 11. Symbols: *-parallelism, R- revers.

Table 11. Character matrix for genus Ursus.

mountains, where its small height allowedit to hide from enemies in grass and reliefcavities. For over wintering, it evidentlydug earth dens at slopes and ravines, usingcaves rather seldom.

The phylogenetic analysis carried out,demonstrated the systematic unity of thecave bears. They may be treated either as asubgenus of Spelearctos within the genusUrsus, or as a distinct genus as has beenrepeatedly proposed by different authors(BORISSIAK, 1932; VERESHCHAGIN,1973; BARYSHNIKOV, 1998). Such apoint of view may be supported by the factthat distinctions, which subdivide the sis-ter species-group (U. arctos and U. mariti -mus), are quite often considered to be thegeneric ones (for example, ELLERMAN &MORRISON-SCOTT, 1966; McKeNNA& BELL, 1997).

Our phylogenetic hypothesis (figure14) is topologicaly identical with thephylogenetic tree for the genus Ursus pre-sented by MAZZA & RUSTIONI (1994).THESE authors interpreted the hypothe-tical ancestors for (deningeri + spelaeus) +(artos + maritimus), and for arctos + mariti -mus clades as belonging to "Ursus gr. arc -tos". The latter was originated, in theiropinion, from the early Ursus aff. etruscus,which was more omnivorous than the laterU. etruscus. Really, the brown bear retainedin dental morphology many features,which are primitive for the cave bears.However, the hypothesis of the origina-tion of the both cave and polar bears fromU. arctos, is unacceptable in our opinion,because if this a case U. arctos would repre-sent the paraphyletic association (see alsoTALBOT & SHIELDS, 1996).

The evolutionary scenario, which we

reconstruct for the cave bears, suggeststheir wide distribution in Eurasia andrapid adaptive radiation. We agree thatthey originated in the end of the EarlyPleistocene. Among Spelearctos, a small U.savini seems to be the most ancient, retai-ning to a considerable degree the omnivo-rous characters of dentition (the lower car-nassial tooth being large; additionaltubercles on molars are slightly develo-ped). It was probably a forest speciesmainly. Its remains are recorded only inEurope (England, Austria), but we believeit may be found also in Asia. To this spe-cies, probably, belongs also U. "etruscus"gombaszoegensis from Gombaszog, in denti-tion of which one may recognize the ten-dency to U. savini and in some degree toU. deningeri (KRETZOI, 1938).

In the early Middle Pleistocene, U. ros -sicus and U. deningeri appeared. The formerretained a small size and settled theAsiatic steppes. It did not reach the skele-ton proportions of U. spelaeus, but itscheek teeth were already partly specializedfor consuming vegetable food.

U. deningeri, in contrast, was an inhabi-tant of the forest and forest-steppe lands-capes of Europe, Caucasus, Central Asiaand south of Siberia. Its size has increased.The crowns of the upper and lower molarsbecame more complicated but even thelatest representatives of the species did notreach the level of complication observed inU. spelaeus.

In the late Middle Pleistocene, theforms transitional to U. spelaeus had appe-ared in Europe, this species predomina-ting in the Late Pleistocene faunas. Thesewere very large bears, inhabiting variousplain and mountain biotopes. In compari-


son with U. rossicus and U. deningeri, itshows the further strengthening of masti-catory structures, which were necessary formore effective fragmentation of plantfood. This contributed to the successfulcompetition of U. spelaeus with otheromnivorous large mammals of the LatePleistocene and species penetration far tonorth, up to the Northern Ural(Medvezhiya Cave at 620 N; see Kuzmina1971).

ACKNOWLEDGEMENTS

We express our gratitude to Prof. N.Vereshchagin (St. Peterburg), Dr. A.Lister and Dr. A. Currant (London), Dr. F.

David (Paris), Dr. A. Forsten and Dr. M.Fortelius (Helsinki) for the help in studythe collections. We are also obliged toProf. N. Drozdov and Dr. N. Ovodov(Krasnoyarsk), Dr. A. Averianov and Dr.N. Abramson (St. Petersburg), and Dr. E.Alexeeva (Izhevsk) who contributed inthis investigation. Dr. SvetlanaBaryshnikova (St. Peterburg) assists us inthe work with manuscript. Dr. I. Barnes(Oxford) improved the English version ofthe paper. Photographs were made byP.Labezkyi (Novosibirsk). We thank Dr.Aurora Grandal d’Anglade (La Coruña) forthe wonderful organization of the CaveBear symposium and editing our manus-cript.


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