Neogene sharks and rays from the Brazilian ‘Blue Amazon’
The lower Miocene Pirabas Formation in the North of Brazil was deposited under influence of the proto-Amazon River and is characterized by large changes in the ecological niches from the early Miocene onwards. To evaluate these ecological changes, the asmobranch fauna of the fully marine, carbonate-...
| Autor principal: | Aguilera, Orangel Aguilera Orangel |
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| Outros Autores: | Luz, Zoneibe Luz Zoneibe, Carrillo-Briceño, Jorge D. Carrillo-Briceño Jorge D., Kocsis, LaÂszlo Kocsis LaÂszloÂ, Vennemann, Torsten W. Vennemann Torsten W., Toledo, Peter Mann de Toledo Peter Mann de, Nogueira, Afonso Nogueira Afonso, Amorim, Kamilla Borges Amorim Kamilla Borges, Moraes-Santos, Heloísa Moraes-Santos Heloísa, Polck, Marcia Reis Polck Marcia Reis, Ruivo, Maria de Lourdes Ruivo Maria de Lourdes, Linhares, Ana Paula Linhares Ana Paula, Monteiro-Neto, Cassiano Monteiro-Neto Cassiano |
| Grau: | Artigo |
| Idioma: | por |
| Publicado em: |
Museu Paraense Emilio Goeldi
2018
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| Assuntos: | |
| Acesso em linha: |
http://repositorio.museu-goeldi.br/handle/mgoeldi/1256 |
| Resumo: |
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The lower Miocene Pirabas Formation in the North of Brazil was deposited under influence of the proto-Amazon River and is characterized by large changes in the ecological niches from the early Miocene onwards. To evaluate these ecological changes, the asmobranch fauna of the fully marine, carbonate-rich beds was investigated. A diverse fauna with 24 taxa of sharks and rays was identified with the dominant groups being carcharhiniforms and myliobatiforms. This faunal composition is similar to other early Miocene assemblages from the proto-Carribbean bioprovince. However, the Pirabas Formation has unique features compared to the other localities; being the only Neogene fossil fish assemblage described from the Atlantic coast of Tropical Americas. Phosphate oxygen isotope composition of elasmobranch teeth served as proxies for paleotemperatures and paleoecology. The data are compatible with a predominantly tropical marine setting with recognized inshore and offshore habitats with some
probable depth preferences (e.g., Aetomylaeus groups). Paleohabitat of taxa particularly found in the Neogene of the Americas (†Carcharhinus ackermannii, †Aetomylaeus cubensis) are estimated to have been principally coastal and shallow waters. Larger variation among the few analyzed modern selachians reflects a larger range for the isotopic composition of recent seawater compared to the early Miocene. This probably links to an increased influence of the Amazon River in the coastal regions during the Holocene. |