Topic
Amerhippus
About: Amerhippus is a research topic. Over the lifetime, 29 publications have been published within this topic receiving 569 citations. The topic is also known as: subgenus of the genus Equus.
Papers
Journal Article•
TL;DR: In this article, the authors deal with the characterization, palaeoenviromental interpretation and chronostratigraphic assignation of the mammals association from Paso Otero Local Fauna.
Abstract: This study deals with the characterization, palaeoenviromental interpretation and chronostratigraphic assignation of the mammals association from Paso Otero Local Fauna. This Local Fauna was found in continental sediments exposed along the banks of the river Quequen Grande, Necochea County (Buenos Aires Province) at lato 38°34' S. and long. 58°42' W. From the zoogeographic point of view, this area belongs to the Guayano-Brazilian Region, Pampean Dominion and it is phytogeographically located within the Chaquean Dominion, Pampean Province. The carrying sediments correspond to an ancient flood plain. They constitute the Guerrero Member of The Lujan Fm. In this unit are identified two sectors: a) lower ""reddish-brown"", and b) upper ""green''; both have been characterized from the geological and faunistic points of view. The faunal assemblage is interpreted as a thanatocenosis whose individuals formed a relatively contemporaneous association, corresponding to the same environment. This
association is characterized by a great variety of herbivores, mainly grazing forms of open areas. There are several dominants species among the marnmals of the Paso Otero Local Fauna: Equus (Amerhippus), Lama guanicoe, Lama morphotype similar to Lama vicugna, Cervidae (morphotype ""a"" and ""b""), Macrauchenia patachonica and Toxodon platensis. They compose a typical association of the Lujanian Land-Marnmal Unit. The following hypothesis are formulated: Hl: Paso Otero Local Fauna is referable to the last part of the Late Pleistocene. It corresponds to the Lujanian Land Mammal Unit in the Pampean Region. H2: the faunistic differences between the ""reddish-brown"" and ""green"" sectors of the Guerrero Member of the Lujan Formation evidence an ecological succesion corresponding to an environmental deterioration. H3: during the sedimentary deposition of the Guerrero Member of the Lujan Formation, the environmental conditions were arid or semiarid. The aridity increased from bottom to top of this unit. H4: mean temperatures lower than the present ones, or at least, biologically-useless winter mean temperatures (lower than 10°C) were verified at the end of the Late Pleistocene in the Pampean Region.
68 citations
TL;DR: Dietary reconstructions inferred from stable isotopes of both genera of horses present in South America document dietary separation and environmental changes in ancient ecosystems, including C3/C4 transitions, and confirm that ancient feeding ecology cannot always be inferred from dental morphology.
Abstract: Background
Stable isotope ratios (13C/12C and 18O/16O) in fossil teeth and bone provide key archives for understanding the ecology of extinct horses during the Plio-Pleistocene in South America; however, what happened in areas of sympatry between Equus (Amerhippus) and Hippidion is less understood.
47 citations
TL;DR: It is shown by retrieving new ancient mtDNA sequences that hippidions and Equus (Amerhippus) neogeus were members of two distinct lineages, and it is demonstrated that while formerly the largest equid from Southern America, Equus was just a member of the species Equus caballus.
Abstract: Hippidions are past members of the equid lineage which appeared in the South American fossil record around 2.5 Ma but then became extinct during the great late Pleistocene megafaunal extinction. According to fossil records and numerous dental, cranial, and postcranial characters, Hippidion and Equus lineages were expected to cluster in two distinct phylogenetic groups that diverged at least 10 MY, long before the emergence of the first Equus. However, the first DNA sequence information retrieved from Hippidion fossils supported a striking different phylogeny, with hippidions nesting inside a paraphyletic group of Equus. This result indicated either that the currently accepted phylogenetic tree of equids was incorrect regarding the timing of the evolutionary split between Hippidion and Equus or that the taxonomic identification of the hippidion fossils used for DNA analysis needed to be reexamined (and attributed to another extinct South American member of the equid lineage). The most likely candidate for the latter explanation is Equus (Amerhippus) neogeus. Here, we show by retrieving new ancient mtDNA sequences that hippidions and Equus (Amerhippus) neogeus were members of two distinct lineages. Furthermore, using a rigorous phylogenetic approach, we demonstrate that while formerly the largest equid from Southern America, Equus (Amerhippus) was just a member of the species Equus caballus. This new data increases the known phenotypic plasticity of horses and consequently casts doubt on the taxonomic validity of the subgenus Equus (Amerhippus).
45 citations
Journal Article•
TL;DR: In this paper, a taxonomic analysis of the fossil remains belonging to Equidae from Brazilian localities is presented, showing that Hippidion principale (Lund) and H. devillei (Gervais) are present in Brazil, the first grouped the large remains, and the second smaller ones.
Abstract: Resumen. Se describen y determinan taxonomicamente los fosiles de Equidae de las localidades brasilenas Se han comparado los restos postcraneales (McIII, MtIII, AS, CAL, 1FIII) de Brasil con los restos de otras localidades de America del Sur mediante analisis multivariados. Los resultados de estos analisis indican que la especie Equus (Amerhippus) neogeus Lund esta representada en todas las localidades de Brasil. Igualmente Hippidion principale(Lund) y H. devillei(Gervais) estan presentes en Brasil, el primero agrupa los restos de gran tamano, y el segundo los mas pequenos en talla. Las tres especies estan representadas en la localidad de Toca dos Ossos (Bahia). Equus (A.) neogeus tambien esta presente en la localidad de Lage Grande (Pesqueira). Nosotros asignamos el material descrito por Souza Cunha como Equus (A.) vandoniia Equus (A.) neogeus Lund. Asi mismo, se actualiza la distribucion y fechados aproximados de las principales localidades con equidos de Brasil. Tambien se discute el papel de la dispersion desde el norte y se examinan sus implicaciones paleobiogeograficas.
Abstract. PLEISTOCENE EQUUS (AMERHIPPUS) AND HIPPIDION (MAMMALIA, PERISSODACTYLA) FROM BRAZIL. PALEOECOLOGICAL AND BIOGEOGRAPHICAL CONSIDERATIONS. Fossil remains belonging to Equidae from Brazilian localities are described and taxonomically determined. We compared the postcranial (McIII, MtIII, AS, CAL, 1FIII) remains from Brazil with other remains from several localities of South America using multivariate analysis. The results indicate that Equus (Amerhippus) neogeusLund is represented in all localities of Brazil. In the same way, Hippidion principale (Lund) and H. devillei (Gervais) are present in Brazil, the first grouped the large remains, and the second the smaller ones. The three species are present in Toca dos Ossos. Equus (A.) neogeusis also present in Lage Grande. We assigned the material described by Souza Cunha as Equus (A.) vandoniito Equus (A.) neogeus. We present an up-to-date fossil distribution and approximate date of the main localities. We discuss the role of dispersal from the North and examine the palaeobiogeographical implications.
41 citations
Journal Article•
TL;DR: The South American patterns of dispersal and distribution of the Hippidion Owen, 1869 and Equus (Amerhippus) Hoffsteller, 1950 species are studied in this paper.
Abstract: The South American patterns of dispersal and distribution of the Hippidion Owen, 1869 and Equus (Amerhippus) Hoffsteller, 1950 species are studied. Likewise their relation with the North American horses and the usefulness as paleoenviromental and climatic indicators are analized. Several hypotheses about the cause of their extinction are considered.
38 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2017 | 3 |
| 2015 | 1 |
| 2013 | 4 |
| 2012 | 5 |
| 2011 | 1 |
| 2008 | 2 |