ISSN 0012�4966, Doklady Biological Sciences, 2012, Vol. 445, pp. 239–243. © Pleiades Publishing, Ltd., 2012.Original Russian Text © G.G. Boeskorov, S.E. Grigoriev, G.F. Baryshnikov, 2012, published in Doklady Akademii Nauk, 2012, Vol. 445, No. 2, pp. 226–230.

239

For a long time, cave bears Ursus (Spelearctos) spp.were considered to be typical representatives of bearsthat lived in Europe during the Pleistocene [1, 2].Later, it has become clear that they also lived in thearea of modern Israel, the Caucasus, South Siberia,Kyrgyzstan, and Korea [3–5]. Dental morphologyand isotope data obtained indicate that cave bears atepredominantly plant food [1, 6]. Due to this, it wasassumed that they were absent in northern Siberia,where omnivorous brown bears (Ursus arctos L.)replaced cave bears due to an influence of environ�mental conditions [7].

It was a complete surprise to find cave bear remainsin northeastern Siberia (on the lower Kolyma Rivernear the settlement of Cherskii and the Oskhordokhlocality on the Adycha River). These finds have greatlyexpanded our understanding of the range of cave bears[8, 9].

These cave bear remains have been found morethan 1500 km northeast of the nearest boundary of therange of cave bears as it was assumed earlier (Fig. 1).Analysis of the stratigraphic position of these findingsand species of the accompanying fauna indicates thatthey belong to the Olyerian Formation preserved inthe Early and Middle Pleistocene sediments in Yaku�tia. Baryshnikov considers the lower jaw from the cavebear found in the area of the settlement of Cherskii tobelong to a small cave bear Ursus savini Andrews,1922, described in the Early–Middle Pleistocene sed�iments of England (the Cromer Forest�bed Forma�tion). Based on some morphological features of the

dental system, this find made it possible to identify apossible new subspecies U. savini nordostensis Barysh�nikov, 2011 [9]. According to molecular analysis, theastragalus bone from the cave bear from the Oskhor�dokh locality is similar to that from a large cave bear(U. deningeri kudarensis Baryshnikov, 1985) from theKudaro region (Southern Caucasus) and was namedas Ursus cf. deningeri [8, 9].

In the summer of 2011, in the Late Cenozoic sedi�ments at the Ulakhan�Sullar locality (the right bank ofthe Adycha River, 8 km downstream of the settlementof Betenkes, the Verkhoyansk region, the Republic ofSakha (Yakutia)) the left mandible of a cave bear wasfound. This finding has no precise stratigraphic attri�bution. Based on the major diagnostic criteria (anabsence of the anterior premolars p1–p3, the complexstructure of the chewing surfaces of molars, the verti�cal position of the anterior edge of the coronoid pro�cess, and a relatively great height of the horizontalbranch), it was established that this lower jaw belongedto a cave bear Ursus (Spelearctos) sp.?, but not to abrown bear Ursus (Ursus) arctos L. (Fig. 2). This is thefirst finding of the cave bear remains at this localityand the third finding in northeastern Russia.

This mandible (dental bone) is well preserved.Molar teeth m1�m3 are preserved. Canine alveoli andcanine diastema are damaged; molar teeth ml and m3are partially damaged. The lower jaw is dark brown incolor; tooth enamel is black. Fossil bones of such colorusually originate from the lower horizons of the sedi�mentary section of the Ulakhan�Sullar locality [9].Due to this, this new finding is most likely to belong tothe late Early and Middle Pleistocene fauna of theOlyerian Theriocomplex.

The Ulakhan�Sullar locality is a 65–80 m cliff ofthe forth above floodplain terrace, where UpperPliocene–Upper Pleistocene sediments are exposed[10–12]. Here, as well as in nearby localities of Kyra�Sullar and Oskhordokh that coeval with the Ulakhan�Sullar locality, bone remains of large mammals of theOlyerian Theriocomplex were found in the lower Early

New Evidence for the Existence of Pleistocene Cave Bearsin Arctic Siberia

G. G. Boeskorova, S. E. Grigorievb, and G. F. Baryshnikovc

Presented by Academician of A.F. Alimov February 16, 2012

Received February 21, 2012

DOI: 10.1134/S0012496612040060

a Diamond and Precious Metal Geology Institute, Siberian Branch of the Russian Academy of Sciences, Yakutsk, 677891 Russiab Yakutsk Scientific Research Institute of Applied Ecologyof the North, North�Eastern Federal University, Yakutsk, Yakutia, 677891 Russiac Zoological Institute of the Russian Academy of Sciences, St. Petersburg, 1999034 Russia

GENERAL BIOLOGY

240

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BOESKOROV et al.

Pleistocene bed. Among them are carnivorous mam�mals (Xenocyon cf. lycaonoides Kretzoi, Canis lupus cf.mosbachensis Soerg., Gulo sp., Homotherium sp.; peris�sodactyl mammals: Equus (Plesippus) verae Sher;artiodactyl mammals: Rangifer sp., Cervalces latifronsJohnson, Bison sp., Soergelia sp., Praeovibos sp.; pro�boscidean mammals: Mammuthus trogontherii(Pohlig) [12–14]. According to the palynological dataobtained, the middle part of the sedimentary sectionof the Ulakhan�Sullar locality formed during the Mid�dle Pleistocene. The use of electron spin resonance(ESR) allowed us to establish that the lower horizon ofthis part of the sedimentary section formed during thelower Middle Pleistocene (ESR dating is 360 ±

20 thousand years); the upper horizon, at the end ofthis period (ESR dating is 212 ± 10 thousand years)[12]. From time to time, the remains of the LateOlyerian mammalian fauna and species of the early

mammoth complex: Mammuthus trogontherii chosari�cus Dubrovo, M. primigenius of the early type, Equuslatipes orientalis Russ., Rangifer sp., Cervus sp., Cerval�ces postremus Vang. et Flerov, Bison sp., Pantheraspelaea cf. fossilis (von Reichenau), Ursus arctos cf.priscus Goldfuss, Canis lupus L., Canis cf. variabilis Peihave been found in this area. The upper part of the sec�tion is characterized by finds of the Late Pleistocenefauna (carnivorous mammals: Canis lupus L., Ursus arc�tos L., Panthera spelaea Goldfuss; proboscidean mam�mals: Mammuthus primigenius of the late type; perisso�dactyl mammals: Equus lenensis Russ., Coelodontaantiquitatis (Blum.); artiodactyl mammals: Cervus ela�phus L., Alces sp., Rangifer tarandus L., Bison priscusBoj., Ovibos pallantis (H. Smith) [7, 11, 12, 15].

The dimensions of the lower jaw found are small forcave bears (Table 1). They are similar to those typicalof the small cave bear Ursus savini. Bears from the

0 500 km

80° 90° 100° 110° 120°

1

2

3

4

5

6

Yana R.

Kolyma R.

Lena R.

Aldan R.

Ob R.

Yenisei R

.

Irtysh R.

Lake Baikal

Fig. 1. The range of cave bears in North Asia. The range assumed earlier: 1, Ursus deningeri; 2, U. spelaeus; 3, U. savini rossicus[3, 5]. New findings: 4, U. cf. deningeri, the Oskhordokh locality [8, 9]; 5, U. savini nordostensis, the Cherskii settlement [9];6, U. savini ssp., the Ulakhan�Sullar locality.

DOKLADY BIOLOGICAL SCIENCES Vol. 445 2012

NEW EVIDENCE FOR THE EXISTENCE OF PLEISTOCENE CAVE BEARS 241

group of large cave bears (U. deningeri von Reichenau,1904, and U. spelaeus Rosenmuller, 1794) are muchlarger [3].

According to the size of the canine alveolus, thenew mandible founded belonged to an adult male cavebear. The horizontal branch of the mandible is high,especially at the level of last mandibular molar m3,where the lower edge of the jaw is convex in shape;towards the anterior, its height becomes lower. There isweak chin�like projection on symphysis; there arethree chin vents; the large angular process is elevated.The articular process is located at the level of thechewing surface of the cheek teeth. The coronoid pro�cess has a very wide base, the anterior is very steeplyelevated above the horizontal branch. The mandibularnotch is not pronounced.

The dental system of the lower jaw found is typicalof cave bears. Anterior premolars pl–p3 and their alve�oli are absent. Judging from the p4 alveolus, this pre�

molar tooth had two separate roots. There is a smalldiastema between p4 and m1.

Molar teeth m1�m3 are slightly worn, with numer�ous additional cusps, especially on m3. The lowerpredatory teeth m1 is bigger; it is longer than tooth m2,which is characteristic of U. savini savini and U. savininordostensis. The talonid m1 is very wide (the width ismore than half the greatest length of the tooth); thehypoconid cusp occupies most of its surface. Theentoconid is composed of two large tubercles. Its baseis in contact with the base of the hypoconid. Due tothis, the talonid basin is not expressed.

The dental crown m2 is occupied by the small tal�onid, which is narrower than the trigonid (indicatingthat the new bone founded is similar to that from theU. savini nordostensis). Compression of the toothcrown, separating the trigonid and the talonid, isexpressed only on the labial side (contraction in thetooth crown of m2 from U. deningeri is well devel�oped).

1

2

3

Fig. 2. Left mandibular bone from the cave bear Ursus (Spelearctos) savini from the Ulakhan�Sullar locality (Yakutia): 1, the labialview; 2, set of molar teeth m1–m3, the lingual view; 3, molar teeth m1– m3, the occlusal view.

242

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BOESKOROV et al.

Dim

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DOKLADY BIOLOGICAL SCIENCES Vol. 445 2012

NEW EVIDENCE FOR THE EXISTENCE OF PLEISTOCENE CAVE BEARS 243

The metaconid is composed of three cusps (thesame as for U. savini nordostensis). The last molar m3is very large; probably, its talonid was not well sepa�rated from the trigonid.

The lower jaw found has archaic morphology char�acteristic of the ancient cave bear U. savini savini andU. deningeri [3]: the steep position of the anterior ofthe coronoid process, its wide base, the great height ofthe horizontal branch, elongated m1, and the smalland narrow talonid m2. These features allow us to cor�relate the jaw from the Ulakhan�Sullar locality withthe typical specimen of U. savini nordostensis. It issomewhat smaller, but this may be due to sexualdimorphism, since male cave bears were significantlylarger than female ones. The new finding is differentfrom the U. savini nordostensis by less elongated m1and a large number of additional cusps on the chewingsurfaces of molars. According to these features, U.savini nordostensis looks archaic. However, it should benoted that the manifestation of cusps on the chewingsurface is very changeable. It is possible that U. savininordostensis belongs to the lower horizon of the Olye�rian theriocomplex, while the jaw described is associ�ated with the upper horizon of this complex (the mid�dle Middle Pleistocene). Further studies, especiallymolecular genetic studies, make it possible to clarifysubspecific identity of this cave bear.

The new finding has confirmed that cave bears wasa part of the fauna of the Olyerian theriocomplex,Yakutia. Both species (Ursus cf. deningeri and thesmaller U. savini) were probably widespread in Siberiaduring the late Early�Middle Pleistocene, and couldbe sympatric species over a significant part of theirranges. The existence of these large herbivores in theArctic Siberia north of the Arctic Circle makes it pos�sible to assume that environmental conditions for cavebears were favorable there. They allowed them, duringa short warm period, to accumulate enough fat to sleepthrough the winter, which could go for many monthsso far north in Siberia.

Thus, the new findings of cave bears in Yakutiaallow us to expand the biodiversity of the PleistoceneTheriofauna of Siberia. Moreover, these findingschange significantly our understanding of the rangesand ecological features of these remarkable extinct

mammals, existed in different landscape zones fromthe Mediterranean Sea to the Siberian Arctic.

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