Morphometry of lower cheek teeth of cave bears (Carnivora, Ursidae) and general remarks on the dentition variability GENNADY F. BARYSHNIKOV AND ANDREY Y. PUZACHENKO Baryshnikov, G. F. & Puzachenko, A. Y.: Morphometryof lower cheek teeth of cavebears (Carnivora, Ursidae) and general remarks on the dentition variability. Boreas. https://doi.org/10.1111/bor.12447. ISSN 0300-9483. The variability of lower 6776 cheek teeth of spelaeoid (Ursus spelaeus, U. kanivetz, U. deningeri, U. kudarensis, U. savini and U. rossicus) and arctoid lineages (extant and extinct U. arctos) recovered from 176 palaeontological localitieswas analysed by methods of univariate and multivariate statistics. For comparison, teeth of U. minimus and U. etruscus species, which are ancestral taxa for cave bears and brown bear, were studied. The performed analyses indicate great variability of tooth crown in lower cheek teeth; no distinct general trend was identified in the changes, except for an increase in p4 roundness and in m3 size from U. minimus to big cave bears. Centroids of U. minimus and U. etruscus are at a great distance from those of cave bears; U. arctos occupies an intermediate position between the twogroups. Molar characteristics in general are close in U. savini and U. rossicus . The bear species are differentiated in the morphospaces by morphometric variations in the lowercheek teeth but less markedly than in the morphospaces of the upper cheek teeth. A test of the inhibitory developmental cascade model showed that a linear relationship between lower molar dimensions became clear only after premolar p4 was included in the model. Evolutionary trends were found in the tooth changes with time (differently expressed in individual species and in different teeth) depending on environments, in particular on the elevation of the locality above the sea level. The allometric pattern differentiation does not always coincide with phylogenetic relationships between taxa, being most often revealed at the subspecies level. There is a dominant covariance between the upper and lower rows of teeth in accordancewith the occlusion scheme. It may vary in manifestation depending on the particular species. Gennady F. Baryshnikov (g_baryshnikov@mail.ru), Zoological Institute Russian Academyof Sciences, Universitet- skaya nab. 1, Saint Petersburg, 199034, Russia; Andrey Y. Puzachenko, Institute of Geography Russian Academyof Sciences, Staromonetnyi per. 29, Moscow 109017, Russia; received 17th November 2019, accepted 25th March 2020. Cave bears belong to the most famous large mammal taxon of the Ice Age fauna of Eurasia. In the European subcontinent, these highly specialized representatives of Ursidae were distributed from the British Isles and Iberian Peninsula in the west to the Urals and Caucasus in the east (Kurt en 1968, 1976; Rabeder et al. 2000) . Now we know that the cave bear range extended far beyond the limits of Europe and their remains have been found in Siberia (as far as Transbaikalia and the Kolyma River in the east), central Asia (Kazakhstan, Kirghizia, China) and, presumably, on the Korean Peninsula (Baryshnikov 2007; Knapp et al. 2009; Sher et al. 2011; Jiangzuo et al. 2018). Numerous recent studies of ancient mtDNA show significant genetic diversity in the cave bear group (Valdiosera et al. 2006; Rabeder et al. 2008, 2010; Knapp et al. 2009; Dabney et al. 2013; Stiller et al. 2014; Knapp 2018; Gretzinger et al. 2019). There are several recognized evolutionary lineages or separate species: Ursus spelaeus Rosenm€ uller, 1794 (Late Pleis- tocene, western Europe and west Siberia), including subspecies U. s. eremus Rabeder, Hofreiter, Nagel et Withalm, 2004 (the Alps and Altai Mountains) and U. s. ladinicus Rabeder et al., 2004 (highlands in Alps), U. deningeri von Reichenau, 1904 (Middle Pleistocene, Europe and central Asia), including subspecies U. d. batyrovi Baryshnikov 2007 (Kirghizia), U. kanivetz Vereshchagin, 1973 (= U. ingressus Rabeder et al., 2004) (Late Pleistocene, central and eastern Europe and the Urals), and U. kudarensis Baryshnikov, 1985 including subspecies U. k. praekudarensis (Baryshnikov 1998) (Middle and Late Pleistocene, Caucasus and, probably, eastern Siberia). We accept two subspecies for U. kanivetz: U. k. kanivetz (Ural) and U. k. ingressus (European area). These data revealed an earlier splitting of U. kudaren- sis, whereas U. spelaeus and U. kanivetz (= ingressus) separated later from U. deningeri (Valdiosera et al. 2006; Baca et al. 2012, 2016; Fortes et al. 2016). According to Dabney et al. (2013), U. deningeri forms a sister lineage to U. spelaeus and U. kanivetz (= ingressus). Early Pleistocene Ursus etruscus G. Cuvier, 1823, is considered the ancestor of cave bears and the brown bear, which had a Palearctic distribution (Kurt en 1968). The small cave bear, U. rossicus Borissiak, 1930 (including subspecies U. r. uralensis Vereshchagin, 1973), is represented in the Middle and Late Pleistocene of eastern Europe, the Urals, western Siberia, and Altai Mountains (Vereshchagin & Baryshnikov 2000; Spassov et al. 2017). Baryshnikov (2007) integrates it with U. savini Andrew, 1922, from the Middle Pleistocene of England (Forest Bed), whereas Spassov et al. (2017) recently suggested the distinction between U. savini (including rossicus) and U. uralensis . According to mitochondrial evidence, it occupies the basal position in the lineage of ‘ingressus’ (Stiller et al. 2014), but is morphologically peculiar (Baryshnikov & Puzachenko 2011, 2017; Baryshnikov et al. 2018). According to DOI 10.1111/bor.12447 © 2020 Collegium Boreas. Published by John Wiley & Sons Ltd