Journal of the Geological Survey of Brazil

Introduction to the special issue on “Brazilian fossiliferous sites with paleobiological importance”

2024-10-05T12:05:43+00:00

To enhance our understanding of Brazilian paleontological heritage, we have launched the special edition titled “Brazilian Fossiliferous Sites with Paleobiological Importance”. A total of seven manuscripts have been accepted and published in Vol. 7 No. SI2 (2024). Recognizing our fossil heritage is essential for the scientific and cultural advancement of Brazil. We strongly encourage paleontologists to continuously publish papers on our rich fossiliferous deposits.

Geological Heritage of the Três Barras Farm section, Ordovician-Silurian record in the Paraná Basin, Brazil

2024-05-15T12:41:15+00:00

The Três Barras Farm section is an outcrop located at the northern edge of the Paraná Basin, in Midwest Brazil. Rocks from the Ordovician-Silurian period are found in this section, represented by the Iapó and Vila Maria formations of the Rio Ivaí Group, which lie directly on the crystalline basement. Devonian rocks of the Furnas Formation are also visible at the top of the section. Although the first fieldwork was conducted there in 1985, the site has been visited by multiple generations of researchers, often for paleontological studies. The fossil record in this section includes invertebrates such as mollusks and brachiopods, mineralized microfossils like ostracods, and palynomorphs such as acritarchs and cryptospores. Analyses conducted up until the 2000s suggested a Lower Silurian age for the complete strata of the Vila Maria Formation, with no invertebrate fossils reported. However, since then, knowledge about the Rio Ivaí Group and the Três Barras Farm section has advanced. Recent studies have challenged the previously assigned Silurian age, with fossil ostracods and brachiopods indicating a Hirnantian age for the upper Iapó and lower Vila Maria formations. Recent palynological research has also reported the presence of palynomorphs in the Iapó Formation for the first time, supporting interpretations of a post-glacial paleoenvironment. Despite these advances, significant knowledge gaps remain regarding the palaeobiodiversity of the Iapó and Vila Maria formations, particularly considering recent discoveries at the Três Barras Farm. This site, located in a remote area, preserves the transition of Late Ordovician strata to Early Silurian ones, enabling studies on Lower Paleozoic
speciation and on the impact of a major glaciation on the biota. Preservation measures include sharing directions and mapping routes to the section, as well as raising awareness among the non-scientific community about its importance.

The Passo das Tropas outcrop complex and the Dicroidium Flora in southern Brazil

2024-09-24T17:36:35+00:00

The Dicroidium flora, composed of different genera of fossil plants, has its first records dating back to the Permian, expanded significantly in diversity in the Triassic, occupying several regions of the Gondwanan territory, becoming a biostratigraphic landmark for the Triassic. In Brazil, this paleoflora is found in the sedimentary rocks of the Santa Maria region, state of Rio Grande do Sul, in locations close to the Passo das Tropas Creek, an informal type section of the Passo das Tropas Member, of the Santa Maria Formation. Pioneering studies on the subject in the region began in 1952, at the Passo das Tropas outcrop, which described the first records of the Dicroidium flora. Over the years, different outcrops were found in this region, which also revealed this paleoflora, such as: “Dom Antônio Reis” outcrop, “Zenir Aita” outcrop and “Espuma” outcrop, where several paleontological collections were carried out. In addition to plant fossils, fish scales and insect wings were recorded in these outcrops. However, these outcrops were totally or partially buried due to the urbanization process in the city of Santa Maria and its surroundings, making further studies impossible. This article presents a historical and stratigraphic review, compiling the work carried out in the last 70 years on the outcrops of the Passo das Tropas Member and presents a new fossil site, the outcrop called Estância dos Montes. A total of 125 specimens were recovered from the Estância dos Montes outcrop, belonging to Dicroidium odontopteroides, D. zuberi, D. lancifolium, Umkomasia sp., Pteruchus sp., Neocalamites sp. and seeds. The fossils presented in this work come from a paleontological rescue carried out at the Estância dos Montes outcrop and are currently deposited in the Paleontological Collection of the Laboratório de Estratigrafia e Paleobiologia of the Universidade Federal de Santa Maria. Not only the importance of preserving and protecting fossil sites and their contents is highlighted, but also the uniqueness of these fossils for the valorization of the regional heritage of Santa Maria and the global relevance of adding more data to understand the biota during the Gondwanan Triassic.

The Bica São Tomé fossil site, Paraná Basin, Rio Grande do Sul, Brazil: A unique window to the dawn of the Mesozoic Era

2024-04-25T13:52:30+00:00

The Early Triassic is pivotal for understanding the recovery and diversification of post-extinction biotas, marking the initial emergence or early diversification of many modern life forms. This phase holds dual significance as it establishes the groundwork for contemporary biodiversity evolution and provides crucial insights into managing present ecological challenges. Focused efforts on the Sanga do Cabral Formation in the Paraná Basin unveil a critical opportunity for studying Early Triassic vertebrates in South America, offering a unique perspective on Western Gondwana's biotic recovery after the End-Permian Mass Extinction. Here, we review the geology and fossil record of the most important fossiliferous outcrop of the Sanga do Cabral Formation, the Bica São Tomé Fossil Site. Prospections at the outcrop have already recovered over two hundred specimens, including holotypes and representative materials of important Early Triassic taxa. Our review aims to demonstrate the relevance of the site and highlight strategies for its preservation. The site includes an unusual representation of archosauromorphs, although its content is dominated by procolophonids. Among the known localities of the Sanga do Cabral Formation, the Bica São Tomé Fossil Site stands out for the unique presence of well-preserved specimens in articulation, such as the nearly complete skeleton of the archosauromorph Teyujagua paradoxa. Even so, most of the record is dominated by fragmentary and reworked specimens. The Bica São Tomé site stands as a beacon for understanding Lower Triassic ecosystems in Latin America, presenting an unparalleled opportunity for Mesozoic exploration in Brazil. The Sanga do Cabral Formation, with its wealth of fossil evidence, promises to enrich our understanding of the Early Triassic period and its significance in shaping modern biodiversity.

Linha São Luiz Geosite, Rio Grande do Sul State: 25 years of discoveries, and a unique window to the Brazilian Mesozoic

2024-07-15T13:01:41+00:00

The Linha São Luiz Geosite is one of the most remarkable outcrops from the central region of Rio Grande do Sul state, southern Brazil. With more than 20 meters of vertical exposure, the locality preserves records of distinct sedimentary episodes, and one of the richest fossil assemblages known in southern Brazil. After a quarter of a century from the first expeditions to the site, the Linha São Luiz still yields new discoveries, registering exquisitely preserved fossils from micro and macrovertebrates, invertebrates, and plants, as well as trace fossils generated by these groups. In this contribution, we assembled representatives from distinct fields of paleontological study to provide a summary of the fossil assemblage from this site. We also briefly discuss the history of research and report geoconservation strategies, which are being implemented at the locality, in order to preserve this important window to the Brazilian Mesozoic.

Geosite Pripiri, Coração de Jesus, Minas Gerais, Brazil: paleontological relevance, quantitative assessment, and initiatives for its promotion

2024-05-06T12:15:16+00:00

The Quiricó Formation is the richest fossiliferous unit of Sanfranciscana Basin. Its paleoasis context (a paleolake record inserted in a desert setting) includes vertebrates, diverse microfossils, and paleobotanical content. This study presents new findings regarding the fossil content of the formation, focusing on discoveries made at the Pripiri Geosite, located in Coração de Jesus municipality, northern part of the state of Minas Gerais, Brazil. Among the discoveries are poorly informative fragments of putative archosaurs and novel microfossiliferous taxa. The microfossil assemblage includes dinocysts and Euglenophyceae, both associated with microbial mat-forming cyanobacteria. These, in turn, comprise the filamentous Pseudoanabaena sp. and the coccoidal cells of Aphanocapsa sp. or Chroococus sp. These microbial mats are recurrent throughout the analyzed stratigraphic succession, primarily observed in sandstone bars featuring distinct evaporitic features. This assemblage provides ecological insights concerning the biota resistance to extreme climatic conditions, and their occurrence in oxygen-rich waters. The preservation of these cells in evaporite-rich rocks is also of great interest for astrobiological studies and the search for past life on Mars. Therefore, due to the importance of Pripiri locality, a quantitative analysis of its geodiversity and geoheritage value were performed, revealing that Pripiri comprises a geosite of national relevance in terms of its scientific, touristic and educational values. In this sense, some initiatives have been carried out to geoconservation and to promote the local geodiversity, aiming to contribute to the paleontological knowledge of the Early Cretaceous, as well as to the social and economic development of Coração de Jesus.

Oligocene - Miocene Angiosperm fossil site in the Boa Vista Basin, Paraíba State, Northeast Brazil

2024-02-19T20:02:23+00:00

The Boa Vista Basin consists of a half-graben controlled by the extensional reactivation of the Serra do Monte Shear Zone, situated within the Transversal Zone, Alto Moxotó Domain of the Borborema Province. The basin was filled by a volcanic-sedimentary sequence characterized by basaltic flows, lacustrine bentonitic clays, and fluvial sandstones and conglomerates of the Campos Novos Formation. The age of the overlying basalts indicates the Oligocene-Miocene boundary. The palynomorph association observed in the Campos Novos Formation presents a preliminary age from the upper Eocene to the lower Oligocene. We identified the fossil material in the sandstones and bentonitic clays. The massive lithic arkosic sandstones present planar and trough cross-bedding and include pieces of silicified wood up to 2 m in length. The bentonitic clays present greenish, light brown, and dark brown colors, with fossil remains identified at the levels of greenish and light brown bentonitic clays in the Juá II and Bravo mines. About 200 specimens of leaves, fruits, and wood fragments were collected at these site, associated with ichnofossils in vertical and horizontal tubes. Among the numerous and varied leaf remains preserved as impressions, Fabaceae, Annonaceae, Lauraceae, Burseraceae, Anacardiaceae, Myrtaceae, and Malvales types dominate. The set attests to a tropical to subtropical flora, similar to elements that grow in the coastal areas of the state of Paraíba today. Some morphotypes are also characteristic of drier regions of Central Brazil. This set has preferential affinities with globally dry and locally humid environments. It seems to have a good relation with the more arid phases that accompanied the global temperature drop intervals at the Oligocene-Miocene boundary, supporting the geological age data.

Fossiliferous sites of the southern coast of Rio Grande do Sul state, Brazil: geoheritage records of Quaternary sea-level, climate and environmental changes

2024-01-25T12:24:42+00:00

The southern coastal plain of Rio Grande do Sul state hosts essential fossil records of both marine and terrestrial faunas that have provided invaluable information about the geological and environmental Quaternary history of southern Brazil. These fossils are found in surface and subsurface deposits on sites stretching from the continental shelf up to coastal lagoons inland. The sites on the shelf are time-averaged lag deposits formed of marine and terrestrial fossils exhumed and mixed together as a result of erosion of the original deposits by sea-level oscillations. Although lacking any precise stratigraphic context, the available numerical dates indicate Middle to late Pleistocene ages. Fossils removed from the shelf by waves today form large Konzentratt-Lagerstätten on the beach, called concheiros. The sites on continental areas occur in barrier-lagoon depositional systems, and include marine deposits formed under higher than present sea levels formed by Middle and late Pleistocene and Early-Middle Holocene marine transgressions. The fossiliferous sites with well-defined stratigraphic context encompass fluvial and aeolian (loess) deposits and paleosols associated with the Middle-late Pleistocene Santa Vitória Alloformation and Cordão Formation outcropping along Chuy Creek. Fossils of late Pleistocene terrestrial and Holocene marine organisms were collected from the bottom and marginal terraces of Mirim Lagoon. Although most sites are not directly under threat today, their wide distribution poses potential problems for protection. Current protection measures for the sites and associated fossils include requests by environmental agencies for preliminary surveys and fossil rescue programs prior to construction projects, and the proposal of a marine-coastal protected area is currently under consideration. Educational programs with schools and exhibits for the general public executed by the museums in the town of Santa Vitória do Palmar have contributed to public awareness about the importance of the regional paleontological heritage and have produced positive feedback and results that increased the number of known fossiliferous sites in the region thanks to communication by local people. These actions are essential to establish protection measures in case new developments emerge in the future that could threaten the sites and their fossils.