South American ungulates
| South American ungulates | ||||||||||||
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| Temporal occurrence | ||||||||||||
| Paleocene to Pleistocene | ||||||||||||
| 60 to 0.01 million years | ||||||||||||
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Meridiungulata | ||||||||||||
| McKenna , 1975 | ||||||||||||
The South American ungulates (Meridiungulata) are a group of extinct mammals that lived in South America during much of the Cenozoic and only became extinct in the Pleistocene . Today 280 genera are known, of which the camel-like Macrauchenia and the hippopotamus-like Toxodon are the best known. Fossils of both genera were first collected by Charles Darwin during his trip on the Beagle .
features
Due to the geographic isolation of South America during large parts of the Cenozoic, there was a great deal of radiation within the South American ungulates and an occupation of different ecological niches . There were species that resembled today's horses , camels, or rhinos without being related to them.
Common features of this group of animals are, among other things, the broad molars that are suitable for grinding and the hoofed feet. As a rule, it was herbivores who, depending on their habitat, fed on a wide variety of plants.
Development history
The isolation mentioned above led to the emergence of a completely separate mammal fauna , comparable to the situation in Australia . There were only relatively few mammalian taxa in South America, including, in addition to the South American ungulates, a diverse marsupial fauna and the articular animals . The rodents ( caviomorpha ) and primates ( New World monkeys ) are (probably in at a later time Oligocene ) over the then much smaller Atlantic on floating islands floating to South America came.
From the Eocene there are also isolated finds from the Antarctic continent , whose climate was significantly warmer than today and which was still connected to South America until 35 to 30 million years ago.
Around 2.5 million years ago, the Isthmus of Panama formed the land connection between North and South America, and the Great American Fauna Exchange took place . Numerous groups of animals that were previously only found in North America immigrated to South America; This had serious consequences for the previously isolated South American fauna. It was largely displaced by camels , horses and deer , and it may also have been unable to cope with the newly immigrated predators , which included dogs and cats . However, a few genera such as Macrauchenia survived until the end of the Pleistocene .
Systematics
External system
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Internal systematics of the Euungulata according to Welker et al. 2015
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The relationship of the South American ungulates remained unexplained for a long time. Because of the hooves on their feet, the South American ungulates were combined with other animals to form the group of " ungulates " (ungulata). The genetic findings of the last few years, however, show that these ungulates are not a natural group, but have only undergone convergent developments as an adaptation to a similar way of life. Among other things, an affiliation to the Afrotheria was discussed, which in addition to paleogeographical prerequisites also spoke anatomical features such as the structure of the spine or the ankle bone , as well as the possible close relationship of the Afrotheria with the articulated animals , the second large, endemic group in South America. The systematic uniformity of the “Meridiungulata” is also largely unclear and was partly assumed due to the common distribution in South America. Individual processors saw, among other things, for some representatives a closer relationship to the also extinct Dinocerata . However, with the help of protein sequencing and a comparison with fossil collagen , which was obtained from the remains of some genetically young representatives of the Meridiungulata (especially Macrauchenia from the Litopterna group and Toxodon from the Notoungulata group ), a close relationship to the odd-toed ungulates could be worked out. Both kinship groups, the odd-toed ungulates and litopterna-notoungulata are now in the parent taxon of Panperissodactyla summarized that within the Euungulata the even-toed ungulates (Artiodactyla) and whales faces (Cetacea) (Cetartiodactyla). The separation of the ancestors of the two groups of South American ungulates from the odd-toed ungulates must have taken place before the Cretaceous-Tertiary boundary due to the long history of the fossil record of the former . The origin of the two groups was probably within the " Condylarthra ", a heterogeneous group of primeval ungulates, which in the Paleogene mainly inhabited the northern hemisphere. A study published almost at the same time on fossil collagen, also determined on Macrauchenia and Toxodon , came to an identical result and called for further analyzes on other forms that had survived into the Pleistocene, such as Mixotoxodon and Neolicaphrium . Both studies were confirmed by molecular genetic analyzes from 2017, which were carried out on fossil remains of Macrauchenia . According to this, the Litopterna and Unpaarhufer lines split from each other about 66.15 million years ago. With regard to the litopterna, anatomical studies from 2020 come to a similar view. They position them as a sister group of the odd ungulate.
Internal system
The South American ungulates are mostly divided into five orders:
- The Litopterna developed into horse-like or camel-like forms; one of the most famous representatives was macrauchenia .
- The Notoungulata were the most species-rich and diverse group that produced both rhinoceros - as well as rabbits - and rodent-like representatives.
- The Astrapotheria were relatively large representatives that survived into the Miocene .
- The Pyrotheria showed similarities with the elephants with their tusk-like incisors .
- The Xenungulata are an early, relatively primitive group that is only known from the Paleocene .
literature
- Tom S. Kemp: The Origin and Evolution of Mammals. Reprinted edition. Oxford University Press, Oxford et al. 2005, ISBN 0-19-850761-5 .
Individual evidence
- Jump up ↑ a b Frido Welker, Matthew J. Collins, Jessica A. Thomas, Marc Wadsley, Selina Brace, Enrico Cappellini, Samuel T. Turvey, Marcelo Reguero, Javier N. Gelfo, Alejandro Kramarz, Joachim Burger, Jane Thomas-Oates, David A. Ashford, Peter D. Ashton, Keri Rowsell, Duncan M. Porter, Benedikt Kessler, Roman Fischer, Carsten Baessmann, Stephanie Kaspar, Jesper V. Olsen, Patrick Kiley, James A. Elliott, Christian D. Kelstrup, Victoria Mullin, Michael Hofreiter, Eske Willerslev, Jean-Jacques Hublin, Ludovic Orlando, Ian Barnes and Ross DE MacPhee: Ancient proteins resolve the evolutionary history of Darwin's South American ungulates. Nature 522, 2015, pp. 81-84, doi: 10.1038 / nature14249
- ↑ Federico L. Agnolin and Nicolás R. Chimento: Afrotherian affinities for endemic South American “ungulates”. Mammalian Biology 76, 2011, pp. 101-108
- ↑ Sen Song, Liang Liu, Scott V. Edwards and Shaoyuan Wu: Resolving conflict in eutherian mammal phylogeny using phylogenomics and the multispecies coalescent model. PNAS 109 (37), 2012, pp. 14942-14947
- ^ Richard A. Fariña, Sergio F. Vizcaíno and Gerardo De Iuliis: Megafauna. Giant beasts of Pleistocene South America. Indiana University Press, 2013, pp. 1-436 (pp. 86-87) ISBN 978-0-253-00230-3
- ↑ Bruce J. Shockey and Federico Anaya Daza: Pyrotherium macfaddeni, sp. nov. (Late Oligocene, Bolivia) and the pedal morphology of pyrotheres. Journal of Vertebrate Paleontology 24 (2), 2004, pp. 481-488
- ↑ Ross MacPhee, Frido Welker, Jessica Thomas, Selina Brace, Enrico Cappellini, Samuel Turvey, Ian Barnes, Marcelo Reguero, Javier Gelfo and Alejandro Kramarz: Ancient protein sequencing resolves litoptern and notoungulate superordinal affinities. In: Esperanza Cerdeño (Ed.): 4th International Palaeontological Congress. The History of Life: A view from the Southern Hemisphere. September 28 - October 3, 2014 Mendoza, Argentina. Mendoza, 2014, p. 186
- ↑ Michael Buckley: Ancient collagen reveals evolutionary history of the endemic South American 'ungulates'. Proceedings of the Royal Society B 282, 2015, S. 20142671, doi: 10.1098 / rspb.2014.2671
- ↑ Michael Westbury, Sina Baleka, Axel Barlow, Stefanie Hartmann, Johanna LA Paijmans, Alejandro Kramarz, Analıá M. Forasiepi, Mariano Bond, Javier N. Gelfo, Marcelo A. Reguero, Patricio López-Mendoza, Matias Taglioretti, Fernando Scaglia, Andrés Rinderknecht, Washington Jones, Francisco Mena, Guillaume Billet, Christian de Muizon, José Luis Aguilar, Ross DE MacPhee and Michael Hofreiter: A mitogenomic time-tree for Darwin's enigmatic South American mammal Macrauchenia patachonica. Nature Communications 8, 2017, p. 15951, doi: 10.1038 / ncomms15951
- ↑ Nicolás R. Chimento and Federico L. Agnolin: Phylogenetic tree of Litopterna and perissodactyla indicates a complex early history of hoofed mammals. Scientific Reports 10, 2020, p. 13280, doi: 10.1038 / s41598-020-70287-5
