The bears from Dmanisi and the first dispersal of early Homo out of Africa

Abstract

We report on the taxonomy and paleodiet of the bear population that inhabited the emblematic palaeoanthropological Early Pleistocene (1.8 Ma) site of Dmanisi (Georgia), based on a dual approach combining morphometrics and microwear of upper and lower teeth. Given that the teeth of Ursus etruscus Cuvier, 1823 from Dmanisi show considerable size variability, their systematic position has been debated. However, a comparative study of the coefficients of variation for tooth size measurements in several modern bear species shows that the variability in tooth size of the ursid population from Dmanisi could result from sexual dimorphism. The analysis of tooth microwear indicates that these bears inhabited a mixed environment of open plain with forest patches, where they had a browsing diet with a substantial contribution of meat and/or fish. Comparative tooth morphometric analyses of modern ursids and fossil U. etruscus indicate that this extinct species had an omnivorous behavior similar to that of extant brown bears. The ecological interactions of the Dmanisi bears with other members of the large mammals community, including the first hominins that dispersed out of Africa, are discussed in the light of this new evidence.

Fossil bear material from the oldest deposits in the Jasna Strzegowska cave (Silesia, southern Poland)

“…etruscus ap peared in Eur asia ~2.2-2.0 Ma and is regarded as a typ i cal Early Pleis to cene fau nal el e ment and rep resen ta tive of a new ur sine evo lu tion ary lin eage of Asi atic or i gin in Eu rope (Ta ble 3; Rustioni and Mazza, 1993a, b;Wag ner, 2010). Re mains of this bear have been found at many lo cal i ties across Eur asia dated be tween 1.8-1.3 Ma, such as Saint-Vallier (Viret, 1954;Argant, 2004), Puebla de Valverde (Kurtén and Crusafon-Pairó, 1977) and Dmanisi (Medin et al, 2019). In the evo lu tion ary his tory of this spe cies, four sub species were de scribed: (1) U. e. saintvallierensis Baryshnikov, 2007 (2.2-2.0 Ma, found in Saint-Vallier and La Puebla de Valverde), char ac terized by rel a tively small teeth, M2 with a nar row talon, m1 with a bi cus pid metaconid, and m2 with a short talonid; (2) U. e. etruscus Cuvier, 1823 (1.8-1.3 Ma, found in Olivola and Pietrafita), dis tin guished by smaller an te rior pre molars and pos te rior mo lars larger than those in U. e. saintvallierensis, M2 with a com par a tively large talon, m1 with a bicus pid metaconid, and m2 with a long talonid; (3) U. e. ve rescagini Sharapov, 1986 (2.0-1.7 Ma, found in Kuruksai), charac terized by the pres ence of large teeth, com par a tively broad M1 and M2, m1 with a monocuspid or bi cus pid metaconid, and m2 with a mod er ately long talonid; and (4) U. e. vekuai Baryshnikov, 2007 (1.9-1.7 Ma, Dmanisi) with teeth larger than in other sub spe cies, with par tic u larly en larged M2, and m1 with a bi cus pid metaconid (Baryshnikov, 2007;Medin et al, 2019).…”

“…Ac cord ing to Medin et al (2019) the morphometric and morpho log i cal vari abil ity dis played by the spec i mens from dif fer ent lo cal i ties in Eu rope is not suf fi cient to sep a rate them into dif ferent sub spe cies and the known vari abil ity can be at trib uted to sex ual di mor phism. Au thors how ever, in gen eral terms, agree with Baryshnikov (2007) in dis tin guish ing two main chronosubspecies, U. e. saintvallierensis and U. e. etruscus, with the lat ter as an autochthonous de scen dent of the for mer form.…”

“…Ac cord ing to Rustioni (1992, 1994), and later Wag ner (2010), this bear was a highly spe cialized spe cies with out de scen dants. By con trast, most authors have re garded U. etruscus as an an ces tor of arctoid and spelaeoid bears (Madurell-Malapeira et al, 2015;Medin et al, 2017Medin et al, , 2019. The main prob lem is that among the lat est re cords of U. etruscus, from which the spe cies was listed (some times ten ta tively), only a few lo cal i ties have yielded abun dant ma terial.…”

“…1. Ursus etruscus: Dmanisi (Medin et al, 2019); Fuente Nueva 3 (Medin et al, 2017); Monte Argentario (Petrucci and Sardella, 2009); Olivola (Mazza and Rustioni, 1992); Pietrafitta (Mazza and Rustioni, 1992); Pirro Nord (Petrucci et al, 2013); Saint Vallier and Senéze (Mazza and Rustioni, 1992;Argant, 2004); Trlica (Vislobokova and Agadjanian, 2015); Tsiotra Vryssi (Koufos et al, 2018); Valdarno (dif fer ent sites, Mazza and Rustioni, 1992); Venta Micena (Medin et al, 2017). 2.…”

Early Pleistocene Caniformia from Palan-Tyukan (Azerbaijan)

“…The morphological characters and the size of the m3 from Palan-Tyukan suggest similarities with the bear teeth from Upper Valdarno and Dmanisi localities (Table 2). Ursus etruscus is the typical ursid species recorded in the faunal assemblages of Eurasia during the Early Pleistocene (Baryshnikov 2007;Wagner 2010;Madurell-Malapeira et al 2014;Medin et al 2017;Wagner et al 2017;Koufos et al 2018;Medin et al 2019). The species was a forest and ecotonal animal and had an omnivorous diet, feeding on both plants and mammals depending upon availability.…”