Paleoecology and evolution of the carnivorous mammalian faunas of South America from the Late Miocene to the Pleistocene: insights from stable isotopic signatures (13C, 15N, 18O) in fossil bones and teeth
Zusammenfassung der Projektergebnisse
In South America, mammalian predators changed completely during the last million years, from an assemblage of species related to marsupials called the sparassodonts, to a more familiar assemblage of bears, cats, dogs and raccoons. Competition between species of similar ecology could have been the cause of the extinction of the sparassodonts and their replacement by placental predators, but alternatively, environmental change may have caused the extinction of sparassodonts and immigrating placental predators just used the empty niches. Isotopic tracking of carbon, oxygen, and nitrogen in fossil bones and teeth provide information about the diet and the habitat of extinct species, and we used this approach to better understand the actual diet of the predators before, during and after the biotic replacement. From about 15 million years ago (Ma) to 10,000 years ago, the herbivore species did not show a clear distinction of their isotopic values, suggesting that most of the different species used to feed on all types of vegetation. This made the determination of prey selection by extinct predators more difficult than expected. Nevertheless, we could determine that sparassodonts were selecting their prey according to their habitat, and were restricted in their distribution when the first wave of carnivores (raccoons) from North America arrived, around 5 Ma. When new groups of carnivores, such as bears, cats, and dogs arrived in South America, they reoccupied the niches left empty by the extinction of sparassodonts. However, we cannot say at the moment if predators with similar morphology (for instance sabretooth sparassodonts and sabretooth cats) really had the same ecology. During the last million year, sabretooth cat and a carnivorous giant bear were competing for large herbivore prey in forested or more open landscape, while wild dogs were more oriented on grassland herbivores. Surprisingly, the large sabretooth cat Smilodon, an ambush predator, was also able to hunt in open grassland, based on its carbon isotopic composition. We also found out that extinct giant ground sloth were purely herbivorous and did not add insects or meat to their diet. Despite several climatic fluctuations during this period, the ecosystem of the pampas seemed relatively stable until 10,000 years ago, when humans started colonizing this area. Some articles published in the medias about the research results of the project: Phys.org, 21st March 2016, Saber-toothed cats hunted on the South American plains. http://phys.org/news/2016-03-saber-toothed-cats-south-american-plains.html Swr.de, 17th March 2016, Der Sabelzahntiger und seine Beute. http://www.swr.de/landesschau-aktuell/bw/tuebingen/tuebinger-wissenschaft-der-saebelzahntiger-und-seine-beute/-/id=1602/did=17132030/nid=1602/ilcoz2/index.html noticiasdelasciencia.com, 23rd March 2016, El terrible tigre dientes de sable no vivia en los bosques. http://noticiasdelaciencia.com/not/18822/el-temible-tigre-dientes-de-sable-no-vivia-en-los-bosques/es/
Projektbezogene Publikationen (Auswahl)
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(2017) Isotopic insight on paleodiet of extinct Pleistocene megafaunal Xenarthrans from Argentina. Gondwana Research 48 7–14
Bocherens, Hervé; Cotte, Martin; Bonini, Ricardo A.; Straccia, Pablo; Scian, Daniel; Soibelzon, Leopoldo; Prevosti, Francisco J.
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(2018) First Ams Radiocarbon Direct Dates on Bones from Extinct Megafauna in Camet Norte (Santa Clara Del Mar, Buenos Aires Province, Argentina). Ameghiniana 55 (1) 126–133
Cotte, Martin; Prevosti, Francisco J.; Hajdas, Irka; Straccia, Pablo; Scian, Daniel; Soibelzon, Leopoldo; Bocherens, Hervé
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2014. Pleistocene trophic systems in the Pampean region (Buenos Aires Province, Argentina): Insights from C and O stable isotopes. Journal of Vertebrate Paleontology 34, supp.1: 113
Cotte, M., Prevosti, F., Soibelzon, L., Bocherens, H.
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2014. South American endemic ungulates in the Pampean region (Buenos Aires Province, Argentina): Ecological insights from stable isotopes (diet, competition and predation pressure). 4th International Paleontological Congress, Abstract Volume, p. 181
Cotte, M., Prevosti, F., Soibelzon, L., Bauriedl, S., Bocherens, H.
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2014. South American giant short-faced bear (Arctotherium angustidens) diet: evidence from pathology, morphology, stable isotopes and biomechanics. Journal of Palaeontology 88: 1240-1250
Soibelzon, L.H., Grinspan, G.A., Bocherens, H., Acosta, W.G., Jones, W.W., Blanco, R.E., Prevosti, F.J.
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2016. Insights into the palaeoecology of Southern South America during the Neogene using the stale isotope analysis of mammalian tooth enamel carbonate. Journal of Vertebrate Paleontology 36, supp.1: 121
Cotte, M., Soibelzon, L., Prevosti, F.J., Vizcaino, S., Bocherens, H.
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2016. Paleobiology of sabretooth cat Smilodon populator in the Pampean Region (Buenos Aires Province, Argentina) around the Last Glacial Maximum: Insights from carbon and nitrogen stable isotopes in bone collagen. Palaeogeography-Palaeoclimatology-Palaeoecology 449: 463-474
Bocherens, H., Cotte, M., Bonini, R., Scian, D., Straccia, P., Soibelzon, L., Prevosti, F.J.
