South American endemic ungulates in the Pleistocene of the Pampean Region (Argentina): Ecological Insights from stable isotopes (diet, competition and predator pressure). Libro de Resúmenes del IV International Paleontological Congress

COTTE, M.; FRANCISCO J. PREVOSTI; SOIBELZON, L.; BAURIELD, S.; BOCHERENS, H.

Congreso; IV International Paleontological Congress; 2014

During the Pleistocene, South American endemic ungulates coexisted with ungulates of NorthAmerican origin as well as with carnivorous species that may have preyed on them. The Pampeanregion (Buenos Aires Province, Argentina) has yielded very rich mammal assemblages of earlyPleistocene (Ensenadan) and late Pleistocene (Lujanan) age including all these groups. We usedcarbon and oxygen isotopic composition of tooth enamel to reconstruct the food preferences andhabitats of South American endemic ungulates, such as Mesotherium, Macrauchenia and 􀀖􀂘􀂡􀂘􀂍􀂘􀂗 (openversus forested environments, wet versus dry). In addition, we compared their carbon and oxygenisotopic composition with those of coeval non-endemic ungulates, such as equids, cervids, andcamelids, as well as proboscideans, to evaluate possible competition and niche partitioning amongthese ungulates. Our data show that all herbivores underwent a shift of approximately 1? in theircarbon and oxygen isotopic values between the early and late Pleistocene that could correspondto a shift in climate. Furthermore, we found a wide spread of habitats and diets for both endemicand invading ungulates, ranging from pure C3 environments to mixed C3-C4 environments. Thereseems to be no clear niche partitioning between the ungulate species based on habitat choice. Mostgroups show broad ranges of habitat and diet indicating no direct competition between speciesof invading and endemic ungulates. Finally, the prey preferences of the predators, which includegiant short-faced bears, large canids and saber-tooth cats, was evaluated using isotopic tracking totest if any group of endemic ungulate was preferentially preyed upon by some of these predators.􀀑􀂞􀂛􀈱􀂍􀂊􀂝􀂊􀈱􀂜􀂞􀂐􀂐􀂎􀂜􀂝􀈱􀂝􀂑􀂊􀂝􀈱􀂜􀂘􀂖􀂎􀈱􀂙􀂛􀂎􀂍􀂊􀂝􀂘􀂛􀂜􀈱􀂙􀂛􀂎􀂏􀂎􀂛􀂛􀂎􀂍􀈱􀂝􀂘􀈱􀂑􀂞􀂗􀂝􀈱􀂒􀂗􀈱􀂜􀂙􀂎􀂌􀂒􀄙􀂌􀈱􀂎􀂗􀂟􀂒􀂛􀂘􀂗􀂖􀂎􀂗􀂝􀂜􀇯􀈱Smilodon seemedto be restricted to prey from wet areas with pure C3 environments while Theriodictis, a large canid,During the Pleistocene, South American endemic ungulates coexisted with ungulates of NorthAmerican origin as well as with carnivorous species that may have preyed on them. The Pampeanregion (Buenos Aires Province, Argentina) has yielded very rich mammal assemblages of earlyPleistocene (Ensenadan) and late Pleistocene (Lujanan) age including all these groups. We usedcarbon and oxygen isotopic composition of tooth enamel to reconstruct the food preferences andhabitats of South American endemic ungulates, such as Mesotherium, Macrauchenia and Toxodon (openversus forested environments, wet versus dry). In addition, we compared their carbon and oxygenisotopic composition with those of coeval non-endemic ungulates, such as equids, cervids, andcamelids, as well as proboscideans, to evaluate possible competition and niche partitioning amongthese ungulates. Our data show that all herbivores underwent a shift of approximately 1? in theircarbon and oxygen isotopic values between the early and late Pleistocene that could correspondto a shift in climate. Furthermore, we found a wide spread of habitats and diets for both endemicand invading ungulates, ranging from pure C3 environments to mixed C3-C4 environments. Thereseems to be no clear niche partitioning between the ungulate species based on habitat choice. Mostgroups show broad ranges of habitat and diet indicating no direct competition between speciesof invading and endemic ungulates. Finally, the prey preferences of the predators, which includegiant short-faced bears, large canids and saber-tooth cats, was evaluated using isotopic tracking totest if any group of endemic ungulate was preferentially preyed upon by some of these predators.Our data suggest that some predators preferred to hunt in specific environments. Smilodon seemedto be restricted to prey from wet areas with pure C3 environments while Theriodictis, a large canid,seemed to prefer prey from more arid areas with mixed C3-C4 environments. The short-faced bearArctotherium presents isotopic values similar to those of Smilodon during the early Pleistocene. Thissuggests, at the very least, some dietary competition between both species. This information willhelp to better understand the final stages of their evolution in this region.seemed to prefer prey from more arid areas with mixed C3-C4 environments. The short-faced bearArctotherium presents isotopic values similar to those of Smilodon during the early Pleistocene. Thissuggests, at the very least, some dietary competition between both species. This information will􀂑􀂎􀂕􀂙􀈱􀂝􀂘􀈱􀂋􀂎􀄴􀂎􀂛􀈱􀂞􀂗􀂍􀂎􀂛􀂜􀂝􀂊􀂗􀂍􀈱􀂝􀂑􀂎􀈱􀄙􀂗􀂊􀂕􀈱􀂜􀂝􀂊􀂐􀂎􀂜􀈱􀂘􀂏􀈱􀂝􀂑􀂎􀂒􀂛􀈱􀂎􀂟􀂘􀂕􀂞􀂝􀂒􀂘􀂗􀈱􀂒􀂗􀈱􀂝􀂑􀂒􀂜􀈱􀂛􀂎􀂐􀂒􀂘􀂗􀇯