O registro fóssil dos depósitos sedimentares proterozoicos, paleozoicos e mesozoicos do Cráton do São Francisco inclui estruturas de origem microbiana (microbialitos, oncólitos), palinomorfos terrestres e marinhos, microfósseis silicosos e carbonáticos de origem marinha, metazoários neoproterozoicos, artrópodes, uma variedade de bioturbações, vertebrados actinopterígios, sarcopterígios e dinossauros. Com exceção dos microbialitos, que são amplamente distribuídos, os fósseis são relativamente escassos se comparados com a extensão geográfica dos depósitos e concentrados em alguns horizontes estratigráficos excepcionais. A raridade dos achados pode ser explicada pela falta de prospecção nas áreas mais distantes das localidades tradicionalmente conhecidas, e também ao baixo potencial de preservação dos fósseis em ambientes deposicionais do Meso e Neoproterozoico, ou de regimes climáticos extremos, i.e. glacial para o Paleozoico e desértico para as porções mesozoicas da Bacia Sanfranciscana. Trabalhos recentes de prospecção, no entanto, têm revelado um potencial significativo para novas descobertas, especialmente na região norte de Minas Gerais. Parte dos registros cenozoicos está distribuída em bacias restritas incluindo as de Gandarela e Fonseca (Eoceno-Mioceno), onde basicamente se preservou folhas de angiospermas e gimnospermas, palinomorfos e insetos, e a Bacia de Juatuba, com registro predominante de folhas de angiospermas O Quaternário constitui uma exceção do ponto de vista da diversidade e abundância de fósseis, especialmente devido à ampla ocorrência de mamíferos em sistemas cársticos. A descontinuidade dos depósitos sedimentares no Cráton do São Francisco mostram hiatos de cerca de 250 milhões de anos entre as seções fossilíferas paleozoicas e de cerca de 125 milhões de anos (Eocretáceo ao Pleistoceno) para a fauna de vertebrados. Palavras-chave: paleontologia, bacias sedimentares, registro fóssil, Proterozoico, Mesozoico, Cenozoico Abstract: THE FOSSIL RECORD OF THE SEDIMENTARY COVERS OF THE SÃO FRANCISCO CRATON IN MINAS GERAIS. The fossil record of the Proterozoic, Paleozoic and Mesozoic sedimentary deposits of the São Francisco Craton includes microbial structures (microbialites and oncoliths), terrestrial and marine palynomorphs, siliceous and calcareous marine microfossils, Neoproterozoic metazoans, arthropods, a variety of bioturbations, actinopterygians, sarcopterygians and dinosaurs. Except for the microbialites, which are widely distributed, the fossils are relatively scarce if compared with the geographic extension of the deposits and concentrated in some exceptional sedimentary horizons. The rarity of the findings can be explained by the lack of fieldwork far from the localities traditionally explored, and the low potential of fossil preservation in paleoenvironments of Paleo and Mesoproterozoic or those under extreme climatic regimes, i.e. glacial for the Paleozoic rocks and desertic for most of the Mesozoic rocks within the Sanfranciscana Basin. On the other hand, recent works have revealed a significant potential for new discoveries, especially in northern Minas Gerais. Part of the Cenozoic record is distributed across restrict basins, including Gandarela and Fonseca (Eocene-Miocene), where basically leaves of angiosperms and gymnosperms, palynomorphs and insects are preserved, and the Juatuba Basin, with predominant record of angiosperm leaves. The Quaternary is an exception of fossil diversity and abundance, due to the widespread occurrence of mammals in karstic deposits. The discontinuity of the sedimentary deposits in the São Francisco Craton shows gaps in the fossil record, which encompass c. 250 my between the Neoproterozoic and Paleozoic, and c. 125 my (Early Cretaceous to Pleistocene) for the vertebrate fauna. Keywords: paleontology, sedimentary basins, fossil record, Proterozoic, Mesozoic, Cenozoic
ABSTRACT. Glyptodon sp. fossil remains can be found throughout Brazil. However, little information is available about their chronological distribution. With the intention to contribute to this issue, we present, as far as we know, the first direct radiocarbon date for 1 specimen of this genus found in Brazil. The osteoderm MZSP-PV660 found in Abismo do Fóssil Cave
Among fossiliferous quaternary deposits, caves are foremost in interest, in relation to richness as well as diversity of fossils preserved therein. The goals of this study are: (i) to review taphonomic research involving paleovertebrates collected in Brazilian caves, and (ii) to propose a controlled collection method for fossils in carbonate soils. The studies about Brazilian paleovertebrate taphonomy in caves began in the XIX century. Until the 1990s, they were conducted in low priority, restricted to taxonomic and paleoenvironmental aspects. After the 1990s, taphonomic studies became more relevant. They were then applied in quaternary deposits in many Brazilian states and used innovative techniques, e.g., chemical analysis and absolute dating methods. Fossil collecting demonstrated satisfactory results in carbonate soils. This technique safely removes bones without causing damage, and spatially reconstructs their location in the substrate, allowing detailed taphonomic interpretations.
A preparação de fósseis é uma tarefa minuciosa, visto que qualquer procedimento incorreto pode causar danos irremediáveis às peças. Alguns autores brasileiros desenvolveram técnicas de preparação que permitem separar os restos esqueletais da rocha que os envolvem. Grande parte dos trabalhos no preparo de fósseis de paleovertebrados, por exemplo, concentram sua tônica no preparo de ictiólitos, assim é preciso desenvolver metodologias próprias para os outros grupos de paleovertebrados. O material deste estudo foi descoberto submerso na caverna Poço Azul do Milú, Bahia. Dentre o material, foi encontrado um esqueleto de preguiça-gigante, Eremotherium laurillardi (Lund, 1842). Tal pesquisa consiste na descrição de uma metodologia de preparação do material supracitado. A fase inicial deu-se com limpeza e estabilização do fóssil, que passou por dois banhos de acetato de polivinila, diluído em água. Após a secagem do material, iniciou-se a restauração das peças desarticuladas. Para isso foi utilizado acetato de polivinila, adesivo de cianoacrilato, gesso e estilete. Devido a seu peso e por ser um material mais fácil de partir-se, o gesso foi substituído pelo poliuretano para a confecção das camas de acomodação. Com as peças preparadas e acomodadas foi possível manuseá-las com maior segurança. Visto que o processo de fossilização do mesmo se deu em ambiente aquático ainda em atividade, o material fóssil apresenta-se melhor preservado em seus detalhes morfológicos. O que foge ao padrão dos achados de Eremotherium laurillardi, todos encontrados em ambientes já secos, sofrendo assim interferência maior do meio cárstico.
We report new data on the geology and the fossil record of the Sanfranciscana Basin in sites to the north of the traditionally explored localities within Minas Gerais. The strata in the new explored area are formed by distinct lithologies, encompassing pelitic rocks with caliche levels and metric bodies of cross-bedded sandstone towards the top, similar to the fluviolacustrine beds of the Areado Group in the southern portions of the basin. Also similar to other regions of the São Francisco Craton, the deposits of the Sanfranciscana Basin studied herein lie discordantly to the rocks of the Bambuí Basin. We preliminarily report neopterygian fish scales, little informative archosaurian bones and an association of the ostracods Ilyocypris- Fossocytheridea. This ostracod association is registered for the first time in the Cretaceous of the Sanfranciscana Basin. The ostracods have been collected from the lacustrine, vertebrate-bearing rocks cropping out in Lagoa dos Patos and Coração de Jesus. The cytherideid Fossocytheridea assigns a minimal Aptian age to its bearing rocks. Its association with Ilyocypris was also reported in Upper Cretaceous oligohaline paleoenvironments in Brazil and Argentina, indicating similar depositional conditions to the strata reported in this paper. The putative affinities of the specimens of the Sanfranciscana Basin with F. ventrotuberculata, and their association with Ilyocypris, raise the hypothesis of a younger age for some levels of that basin in northern Minas Gerais, perhaps ranging into the Late Cretaceous. Keywords: Ostracoda, Archosauria, Areado Group, Cretaceous, Gondwana
We describe the first occurrence of biogenic traces made by mammals within an iron formation cave located in the Serra da Ferrugem ridge, in Southeastern Brazil. these bioerosions are tooth traces produced in boulders, walls and floor within the cave. The traces occur as sets of two or more grooves, which are highly variable in size. The grooves were compared to tooth traces artificially produced by imprinting the incisors of different mammal species collected in the cave region on soft clay. Among those, the following taxa are potential tracemakers: Akodon sp., Oligoryzomys sp., Necromys lasiurus, Rhipidomys mastacalis, Oecomys gr. concolor, Trinomys moojeni, and Hydrochoerus hydrochaeris. the age of the traces is unknown; therefore, any discussion on its fossil nature is circumstantial. regardless of its relevance to paleontology, the presence of ichnological features should be considered as an additional cave value, according to the current Brazilian legislation regarding cave protection.
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