Rotas migratórias de braquiópodes (família Leptocoeliidae & família Tropidoleptidae) das bordas devonianas das bacias do Paraná e Parnaíba
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Data
2019-12-10
Autores
Ribeiro, Victor Rodrigues
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Universidade Estadual Paulista (Unesp)
Resumo
A distribuição dos continentes no Devoniano era diferente do que temos atualmente. As bacias sedimentares que ocupavam as áreas próximas do Equador (e.g. Parnaíba, Amazonas, Solimões) hospedavam ecossistemas com uma grande diversidade de espécies. Por outro lado, as bacias que ocupavam regiões de alta latitude, como Paraná, hospedavam uma fauna de águas mais frias. Esta fauna, formalmente nomeada como Fauna Malvinocáfrica, é composta por uma diversidade baixa de Gastrópodes, Moluscos, Trilobitas e Braquiópodes (Australocoelia, Australospirifer, Australostrophia, Iridistrophia, Meristelloides, Derbyina, Lingula e Orbiculoidea).NaBaciadoParaná(Centro-Sulbrasileiro)afaunadevonianaestá retratada na Formação Ponta Grossa, já na Bacia do Parnaíba (Norte-Nordeste brasileiro) a fauna ocorre pontualmente, justamente devido às condições paleoambientais e climáticas. No Devoniano Médio, as bacias do Paraná e Parnaíba, em resposta a subida do nível do mar, passaram por um período de mistura faunística, justificada pela ocorrência de Tropidoleptus carinatus (espécie de mares equatoriais) no meio das faunas Malvinocáfricas da Bacia do Paraná. Com a finalidade de averiguar tais eventos de dispersão, foram levados em consideração os gêneros Tropidoleptus e Australocoelia, sendo um oriundo de mares quentes e outro de mares frios, respectivamente. Análises morfofuncionais dos exemplares, levantamentos bibliográficos e trabalhos de campo indicaram que espécies de braquiópodes equatoriais não adentraram a Bacia do Paraná, restringindo-se apenas às regiões temperadas do Parnaíba, Amazonas e nas bacias Bolivianas (Madre de Dios e Tarija). No entanto, exemplares de Australocoelia foram identificados nas bacias do Parnaíba e do Amazonas, indicando que faunas de ambientes frios foram capazes de adentrar os ambientes tropicais. Assim, podemos inferir que as bacias do Paraná e Parnaíba estiverem conectadas durante o Devoniano Médio, no entanto a Bacia do Parnaíba funcionou como um ecótono para os braquiópodes, onde foram encontrados braquiópodes austrais e boreais.
The distribution of continents in the Devonian was different from what we have today. The sedimentary basins that occupied the areas near Ecuador (e.g. Parnaíba, Amazonas, Solimões) hosted ecosystems with a big diversity of species. On the other hand, basins that occupied high latitude regions, such as Paraná Basin, hosted a colder water fauna. This fauna, formally named as Malvinokaffric Realm, is composed of a low diversity of Gastropods, Molluscs, Trilobites and Brachiopods (Australocoelia, Australospirifer, Australostrophia, Iridistrophia, Meristelloides, Derbyina, Lingula and Orbiculoidea). In the Paraná Basin (Center-South Brazil) the Devonian fauna is portrayed in the Ponta Grossa Formation, while in the Parnaíba Basin (North-Northeast Brazil) the fauna occurs punctually, precisely due to paleoenvironmental and climatic conditions. In the Middle Devonian, the Paraná and Parnaíba basins, in response to sea level rise, underwent a period of faunal mixing, justified by the occurrence of Tropidoleptus carinatus (species from equatorial seas) in the middle of the Malvinokaffric faunas of the Paraná Basin. In order to investigate such dispersal events, the genera Tropidoleptus and Australocoelia were taken into consideration, one from warm seas and one from cold seas, respectively. Morphofunctional analyzes of the specimens, bibliographic surveys and fieldwork indicated that species of equatorial brachiopods did not enter the Paraná Basin, but were restricted to the temperate regions of Parnaíba, Amazonas and Bolivian basins (Madre de Dios and Tarija). However, Australocoelia specimens were identified in the Parnaíba and Amazonas basins, indicating that cold environment faunas were able to enter tropical environments. Thus, we can infer that the Paraná and Parnaíba basins are connected during the Middle Devonian, however the Parnaíba Basin functioned as an ecotone for the brachiopods, where southern and boreal brachiopods were found.
The distribution of continents in the Devonian was different from what we have today. The sedimentary basins that occupied the areas near Ecuador (e.g. Parnaíba, Amazonas, Solimões) hosted ecosystems with a big diversity of species. On the other hand, basins that occupied high latitude regions, such as Paraná Basin, hosted a colder water fauna. This fauna, formally named as Malvinokaffric Realm, is composed of a low diversity of Gastropods, Molluscs, Trilobites and Brachiopods (Australocoelia, Australospirifer, Australostrophia, Iridistrophia, Meristelloides, Derbyina, Lingula and Orbiculoidea). In the Paraná Basin (Center-South Brazil) the Devonian fauna is portrayed in the Ponta Grossa Formation, while in the Parnaíba Basin (North-Northeast Brazil) the fauna occurs punctually, precisely due to paleoenvironmental and climatic conditions. In the Middle Devonian, the Paraná and Parnaíba basins, in response to sea level rise, underwent a period of faunal mixing, justified by the occurrence of Tropidoleptus carinatus (species from equatorial seas) in the middle of the Malvinokaffric faunas of the Paraná Basin. In order to investigate such dispersal events, the genera Tropidoleptus and Australocoelia were taken into consideration, one from warm seas and one from cold seas, respectively. Morphofunctional analyzes of the specimens, bibliographic surveys and fieldwork indicated that species of equatorial brachiopods did not enter the Paraná Basin, but were restricted to the temperate regions of Parnaíba, Amazonas and Bolivian basins (Madre de Dios and Tarija). However, Australocoelia specimens were identified in the Parnaíba and Amazonas basins, indicating that cold environment faunas were able to enter tropical environments. Thus, we can infer that the Paraná and Parnaíba basins are connected during the Middle Devonian, however the Parnaíba Basin functioned as an ecotone for the brachiopods, where southern and boreal brachiopods were found.
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Devoniano Médio, Tropidoleptus carinatus, Australocoelia, Paleobiogeografia, Bacia do Paraná, Bacia do Parnaíba, Middle Devonian, Paleobiogeography, Parana Basin, Parnaíba Basin