Paleobiology, 29(2), 2003, pp. 205±229 Paleoecological reconstruction of a lower Pleistocene large mammal community using biogeochemical (d13C, d15N, d18O, Sr: Zn) and ecomorphological approaches Paul Palmqvist, Darren R. GroÈcke, Alfonso Arribas, and Richard A. FarinÄa Abstract.ÐEcomorphological and biogeochemical (trace element, and carbon, nitrogen, and oxygen isotope ratios) analyses have been used for determining the dietary niches and habitat preferences of large mammals from lower Pleistocene deposits at Venta Micena (Guadix-Baza Basin, Spain). The combination of these two approaches takes advantage of the strengths and overcome the weak- 13 ness of both approaches. The range of d Ccollagen values for ungulate species indicates that C3 plants 13 were dominant in the diet of these mammals. d Ccollagen values vary among ungulates: perissodac- tyls have the lowest values and bovids the highest ones, with cervids showing intermediate values. The hypsodonty index measured in lower molar teeth and the relative length of the lower premolar tooth row indicate that the horse, Equus altidens, was a grazing species, whereas the rhino, Ste- 13 phanorhinus etruscus, was a mixed feeder in open habitats. The similar d Ccollagen values shown in both perissodactyls does not re¯ect differences in feeding behavior with other ungulates, but rather a lower isotope enrichment factor in these monogastric herbivores than in ruminants, owing to their lower metabolic ef®ciency. The cervids Eucladoceros giulii and Dama sp. show low hypsodonty val- ues, indicating that they were mixed feeders or browsers from forested habitats, an ecomorphol- 15 ogically based conclusion corroborated in the former by its low d Ncollagen content (canopy effect). Bovid species (Bovini aff. Leptobos, Soergelia minor,andHemitragus albus) presumably inhabited 15 open environments, according to their comparatively high hypsodonty and d Ncollagen values. Car- nivore species (Homotherium latidens, Megantereon whitei, Pachycrocuta brevirostris, Canis falconeri,and 15 Canis etruscus) exhibit higher d Ncollagen values than ungulates. These results record the isotopic enrichment expected with an increase in trophic level and are also supported by low bone Sr:Zn 15 ratios. The elevated d Ncollagen value for a sample of Mammuthus meridionalis, which came from an 15 individual with unfused epiphyses, con®rms that it was a suckling animal. The d Ncollagen value of the scimitar-cat H. latidens is well above that obtained for the young individual of Mammuthus, which indicates that juvenile elephants were an important part of its diet. The hippo, Hippopotamus 15 antiquus, yielded unexpectedly high d Ncollagen values, which suggest feeding on aquatic, non-N2- 18 ®xing plants. The high d Ohydroxyl values of bovids Hemitragus and Soergelia and of cervid Dama in- dicate that these ungulates obtained most of their water requirements from the vegetation. The 18 megaherbivores and Eucladoceros exhibit the lowest d Ohydroxyl values, which suggest increased wa- ter dependence for them. Paleosynecological analysis was based on the relative abundance of spe- cies of large mammals from different ecological categories, determined by feeding behavior and locomotion types. The comparison of the frequencies of such categories in Venta Micena with those found in modern African communities indicates that the composition of the paleocommunity close- ly resembles those of savannas with tall grass and shrubs. The net above-ground primary produc- tivity estimated for the on-crop biomass of the mammalian species preserved in the fossil assem- blage also yields a ®gure congruent with that expected for an open environment. Paul Palmqvist. Departamento de GeologõÂa y EcologõÂa (AÂ rea de PaleontologõÂa), Facultad de Ciencias, Cam- pus Universitario de Teatinos, 29071 MaÂlaga, Spain. E-mail: [email protected] Darren R. GroÈcke. Department of Geology, Royal Holloway, University of London. Egham Hill, Egham, Surrey TW20 0EX, United Kingdom. E-mail: [email protected] Alfonso Arribas. Museo Geominero, Instituto GeoloÂgico y Minero de EspanÄa (IGME), RõÂos Rosas, 23, 28003 Madrid, Spain. E-mail: [email protected] Richard A. FarinÄa. Departamento de PaleontologõÂa, Facultad de Ciencias, Universidad de la RepuÂblica, IguaÂ, 4225, 11400 Montevideo, Uruguay. E-mail: fari;[email protected] Accepted: 1 November 2002 Introduction Pleistocene, with an estimated age of 1.3 6 0.1 Venta Micena (378449150N, 2824990W, eleva- Ma (Arribas and Palmqvist 1999). The fossils tion 974.5 m) lies near the village of Orce, in were preserved in 98±99% pure micritic lime- the eastern sector of the Guadix-Baza Basin stone, precipitated on a caliche paleosol that (Betic Chains, southeastern Spain; Fig. 1). This surrounded a shallow Pleistocene lake with site is dated by biostratigraphy to the early swampy marginal zones (Arribas and Palm- q 2003 The Paleontological Society. All rights reserved. 0094-8373/03/2902-0005/$1.00 206 PAUL PALMQVIST ET AL. FIGURE 1. Geological map of the Betic Chains, showing the situation of the Guadix-Baza intramontane basin and the stratigraphic pro®le of the early Pleistocene locality at Venta Micena. This sedimentary basin was endorheic (i.e., characterized by interior drainage) until late Pleistocene times, thus facilitating an exceptional record of Plio- Quaternary taphocenoses of large mammals preserved in swampy and lacustrine sediments. The 80±120-cm-thick Venta Micena stratum (VM-2) is one of the various fossiliferous units in the sedimentary sequence of Orce, whose surface stands out topographically in the ravines of the region and can be followed along ;2.5 km. This stratum has the following vertical structure from bottom to top: (1) A basal unit that is one-third to one-half the total thick- ness, formed by homogeneous micrite with some carbonate nodules and small mud banks. The sediment preserves abundant shells of freshwater mollusks and is sterile in vertebrate fossils, thus attesting to a ®rst generalized la- custrine stage in the region, in which the micrite was precipitated in water of variable depth. The absence of both pyrite and carbonate facies rich in organic matter is evidence that the lake was not eutrophic. (2) A 4±15-mm-thick calcrete paleosol (hardpan) developed on the surface of the micrite sediments. The calcrete forms an irregular sur- face, subparallel to the bedding plane, and is thicker at topographic highs. It de®nes a stratigraphic unconformity indicating a major drop of the Pleistocene lake level, and thus the emergence of an extensive plain around the lake. (3) An upper unit of micrite deposited in a subsequent rise of the lake level, which continues up to the top of the stratum, showing rootmarks, mudcracks, and a high density of fossil bones of large mammals resting on the pa- leosol. qvist 1998). The macrovertebrate assemblage Arribas and Palmqvist 1998). The selection by comprises ;5800 identi®able skeletal remains predators of speci®c ungulates was basically a of 225 individuals, which belong to 20 species function of differences in the body mass of ju- of large mammals (Table 1). venile and adult prey individuals, as well as Taphonomic research on the composition of in the sex of prey (Palmqvist et al. 1996). Major the Venta Micena assemblage has shown that taphonomic biases in the preservation of the the skeletal remains were scavenged by the gi- bone assemblage are related to the selective ant, short-faced hyena Pachycrocuta brevirostris transport by hyenas of ungulate carcasses and from carcasses of ungulates preyed upon by body parts to their maternity dens, and to the ¯esh-eating carnivores (Palmqvist et al. 1996; preferential consumption of low-density, mar- ECOLOGY OF PLEISTOCENE MAMMALS 207 TABLE 1. Herbivores larger than 10 kg and carnivores larger than 5 kg found in the fauna of Venta Micena, their trophic habits, their number of identi®able specimens (NISP), their minimal number of individuals (MNI)(data from Palmqvist and Arribas 2001), their estimated mass (data from Palmqvist et al. 1996), their calculated on-crop bio- mass, and their mass-speci®c basal metabolic rate. Abbreviations: Br 5 browser, .75% leaves. Mf 5 mixed feeder, 25±75% grass. Gr 5 grazer, .75% grass. F 5 ¯esh eater, .70% vertebrate ¯esh in diet. Mi 5 meat and insect eater, 20±70% ¯esh. Mb 5 meat and bone eaters. O 5 omnivore, ,20% ¯esh. Basal Body mass On-crop metabolic Trophic NISP MNI (adults, biomass rate Species habits (teeth/bones) (juv./adults) in kg) (kg km22) (J kg21 s21) Mammuthus meridionalis Mf 48 (16/32) 5 (4/1) 6000 840.5 0.47 Hippopotamus antiquus Gr 58 (19/39) 5 (3/2) 3000 706.8 0.55 Bovini aff. Leptobos Gr 775 (382/393) 27 (16/11) 450 439.8 0.89 Soergelia minor Mf 334 (215/129) 13 (3/10) 225 369.9 1.06 Praeovibos sp. Gr 6 (3/3) 1 (0/1) 320 403.9 0.97 Hemitragus albus Gr 305 (209/96) 14 (2/12) 75 281.0 1.39 Caprini gen. et sp. indet. Mf 1 (0/1) 1 (0/1) 10 169.8 2.31 Eucladoceros giulii Br 962 (557/405) 36 (15/21) 385 423.0 0.93 Dama sp. Mf 417 (231/186) 20 (3/17) 95 298.1 1.31 Stephanorhinus etruscus Br 90 (55/35) 6 (2/4) 1500 594.3 0.66 Equus altidens Gr 2562 (1183/1379) 70 (32/38) 350 413.1 0.95 Vulpes praeglacialis Mi 24 (19/5) 1 (0/1) 5 3.6 2.93 Canis falconeri F 65 (40/25) 3 (0/3) 30 6.9 1.80 Canis etruscus Co 33 (20/13) 4 (0/4) 10 4.7 2.43 Lynx aff. issiodorensis F 6 (2/4) 1 (0/1) 10 4.7 2.43 Megantereon whitei F 16 (7/9) 3 (0/3) 100 10.7 1.30 Homotherium latidens F 7 (6/1) 2 (0/2) 200 13.8 1.08 Pachycrocuta brevirostris Mb 62 (34/28) 10 (4/6) 70 9.4 1.44 cf.