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| Palmqvist, P.; Gr”cke, D.R.; Arribas, A.; Fari¤a, R.A. | |
| Paleoecological reconstruction of a lower Pleistocene large mammal community using biogeochemical and ecomorphological approaches | |
| 2003 Paleobiology (29): 205-229 | |
Ecomorphological 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 weakness of both approaches. The range of d13Ccollagen values for ungulate species indicates that C3 plants were dominant in the diet of these mammals. d13Ccollagen values vary among ungulates: perissodactyls 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, _Stephanorhinus etruscus_, was a mixed feeder in open habitats. The similar d13Ccollagen values shown in both perissodactyls does not reflect differences in feeding behavior with other ungulates, but rather a lower isotope enrichment factor in thesemonogastric herbivores than in ruminants, owing to their lower metabolic efficiency. The cervids _Eucladoceros giulii _and _Dama _sp. show low hypsodonty values, indicating that they were mixed feeders or browsers from forested habitats, an ecomorphologically based conclusion corroborated in the former by its low d15Ncollagen content (canopy effect). Bovid species (Bovini aff. _Leptobos_, _Soergelia minor_, and _Hemitragus albus_) presumably inhabited open environments, according to their comparatively high hypsodonty and d15Ncollagen values. Carnivore species (_Homotherium latidens_,_Megantereon whitei_, _Pachycrocuta brevirostris_, _Canis falconeri_, and _Canis etruscus_) exhibit higher d15Ncollagen 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 ratios. The elevated d15Ncollagen value for a sample of _Mammuthus meridionalis_, which came from an individual with unfused epiphyses, confirms that it was a suckling animal. The d15Ncollagen 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 antiquus_, yielded unexpectedly high d15Ncollagen values, which suggest feeding on aquatic, non-N2-fixing plants. The high d18Ohydroxyl values of bovids _Hemitragus _and _Soergelia _and of cervid _Dama _indicate that these ungulates obtained most of their water requirements from the vegetation. The megaherbivores and _Eucladoceros _exhibit the lowest d18Ohydroxyl values, which suggest increased water dependence for them. Paleosynecological analysis was based on the relative abundance of species 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 closely resembles those of savannas with tall grass and shrubs. The net above-ground primary productivity estimated for the on-crop biomass of the mammalian species preserved in the fossil assemblage also yields a figure congruent with that expected for an open environment. |
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