UERJ - Universidade do Estado do Rio de Janeiro / Rio de Janeiro State University
Department of Stratigraphy and Paleontology
O livro didático é atualmente um dos instrumentos direcionadores do processo de ensino-aprendizagem. Análises dos conteúdos de Biologia nesses livros são importantes por revelarem problemas embutidos nessas obras e permitir uma escolha... more
O livro didático é atualmente um dos instrumentos direcionadores do processo de ensino-aprendizagem. Análises dos conteúdos de Biologia nesses livros são importantes por revelarem problemas embutidos nessas obras e permitir uma escolha mais informada dos livros para a abordagem de conteúdos específicos. Neste trabalho foi realizada uma análise da abordagem dos conteúdos de Paleontologia nos livros didáticos de Biologia, na perspectiva de conhecer a realidade atual da veiculação desse tema nos livros e fornecer informações úteis na escolha de melhores livros didáticos de Biologia quanto à temática paleontológica. Cinco livros didáticos de Biologia do Ensino Médio foram escolhidos, onde os temas básicos de Paleontologia foram analisados. Das obras analisadas, quatro apresentam boa abordagem, incluindo descrições detalhadas dos principais temas paleontológicos. Erros conceituais foram encontrados e, além disso, novos conceitos e abordagens adotados pela comunidade científica têm sido raramente incorporados nessas publicações. Ressalta-se a necessidade de consulta a livros recentes da Paleontologia para a atualização das obras analisadas, além de uma melhor articulação dos conceitos paleontológicos com outros temas biológicos interrelacionados. Adicionalmente, sugere-se a melhoria nas explicações de temas mais complexos como "datação de fósseis" e "processos de fossilização".
BRAZILIAN PLEISTOCENE MEGAFAUNAL TAPHONOMY: FLUVIAL TRANSPORT INDEX (FTI) IN BONE REPRESENTATIVITY ANALYSES.
- by Hermínio Araújo-Júnior and +1
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- Taphonomy
CARNIVORE/SCAVENGER TEETH MARKS ON PLEISTOCENE MAMMALS FROM THE NORTHEASTERN BRAZIL. In this work, the first occurrence of carnivore/scavenger teeth marks on Pleistocene fossil mammals collected in the Northeastern Brazil is reported. The... more
CARNIVORE/SCAVENGER TEETH MARKS ON PLEISTOCENE MAMMALS FROM THE NORTHEASTERN BRAZIL. In this work, the first occurrence of carnivore/scavenger teeth marks on Pleistocene fossil mammals collected in the Northeastern Brazil is reported. The fossils are from the "Tank of the Jirau", Itapipoca municipality, Ceará State, and are housed in the Museu de Pré-história de Itapipoca. The observed features, which are assigned to a largesized canid, correspond to scratches marks mostly perpendicular to the long axis of the bone, occurring mainly in ribs, vertebrae, tibiae and ulnae. Based on the size of the scratches, the geographical distribution and dietary habits of canids from the Late Pleistocene of Brazil, Protocyon troglodytes (Lund) is the most likely producer of the observed features, although this taxon is not represented in the Jirau fossil accumulation.
- by Hermínio Araújo-Júnior and +1
- •
- Taphonomy
Fósseis de mamíferos quaternários são conhecidos para vários depósitos fossilíferos do Estado do Rio Grande do Norte. No entanto, grande parte do conhecimento sobre essa mastofauna é taxonômico, enquanto que aspectos estratigráficos,... more
Fósseis de mamíferos quaternários são conhecidos para vários depósitos fossilíferos do Estado do Rio Grande do Norte. No entanto, grande parte do conhecimento sobre essa mastofauna é taxonômico, enquanto que aspectos estratigráficos, tafonômicos e paleoecológicos têm sido pouco discutidos. Este trabalho é uma síntese do conhecimento sobre as ocorrências de mamíferos fósseis no Quaternário do Estado do Rio Grande do Norte. É fornecida uma listagem completa e atualizada dos táxons e das localidades fossilíferas e são discutidos aspectos relacionados à tafonomia, diversidade, posicionamento geocronológico e implicações paleoecológicas das tafocenoses. Os depósitos fossilíferos quaternários do Rio Grande do Norte compreendem tanques naturais, lagoas e depósitos cársticos e costeiros. Trinta táxons de mamíferos são conhecidos para os depósitos fossilíferos potiguares, incluindo megamamíferos e mamíferos de grande, médio e pequeno porte. A diferença de padrões preservacionais observados sugere a atuação de processos tafonômicos distintos em cada tipo de depósito. No que se refere aos aspectos paleoecológicos, as características auto-ecológicas conhecidas e ou propostas para os táxons encontrados no Rio Grande do Norte sugerem a ocorrência de um ambiente diferente do atual, onde predominavam savanas entremeadas por áreas florestais mais esparsas. No entanto, tais informações devem ser tomadas com cautela, já que as coletas de mamíferos quaternários realizadas na maioria desses depósitos não tiveram controle tafonômico e estratigráfico apropriado. Além disso, a atribuição dessas acumulações fossilíferas ao Pleistoceno tardio (assim como outras faunas quaternárias nordestinas) tem se fundamentado predominantemente em correlações bioestratigráficas, havendo necessidade de mais datações absolutas para a proposição de um referencial geocronológico mais sólido. Palavras-chave: Pleistoceno, mamíferos, diversidade, tafonomia, paleoecologia. FOSSIL MAMMAL ASSEMBLAGES OF THE QUATERNARY FROM RIO GRANDE DO NORTE STATE, NORTHEAST-ERN BRAZIL: DIVERSITY AND TAPHONOMIC AND PALEOECOLOGICAL ASPECTS. Quaternary fossil mammals are known from several sites in the Rio Grande do Norte State, Brazil. However, the information regarding the knowledge of this peculiar fauna is mostly taxonomic, while stratigraphic, taphonomic and paleoecological aspects were seldom discussed. This work is a synthesis of the knowledge regarding the fossil mammal occurrences from the Quaternary of Rio Grande do Norte State. Here we offer an up to date list of the mammal fauna and best known sites from Rio Grande do Norte State and discuss several issues related to age, taphonomic and diversity patterns as well as the paleoecological implications stemming from those patterns. The fossiliferous sites of Rio Grande do Norte comprise natural tanks, lakes and carstic and costal deposits. Thirty taxa are known from these sites, including megamammals and several large, medium and small sized mammal species. The differences observed in preservational patterns suggest distinct taphonomic processes acting in distinct deposits. The inferred or known autoecologies for the mammal taxa recorded for the Quaternary of Rio Grande do Norte state suggest the presence of environmental settings comprising grasslands mixed with forest fragments. Nonetheless, these inferences should be considered with caution, as the fossil material on which they were based were collected without proper stratigraphic and taphonomic control. Moreover, the age usually attributed to these deposits (Late Pleistocene) was based on preliminary biostratigraphic correlations pending absolute datings in order to establish a more sound geochronological framework.
A análise multivariada da representatividade taxonômica de mamíferos em tanques naturais e dos depósitos cársticos do Quaternário do Nordeste do Brasil é apresentada. O método empregado foi a análise de agrupamentos. Com fins... more
A análise multivariada da representatividade taxonômica de mamíferos em tanques naturais e dos depósitos cársticos do Quaternário do Nordeste do Brasil é apresentada. O método empregado foi a análise de agrupamentos. Com fins comparativos, também foram incluídas na análise tafocenoses de mamíferos do sul do Brasil e Argentina, em geral contidos em unidades litoestratigráficas formais. Os resultados demonstram que os depósitos setentrionais formam um agrupamento principal e se diferenciaram dos meridionais por conter táxons considerados endêmicos para a região intertropical brasileira. Para as áreas do Nordeste, os resultados evidenciaram dois subgrupos, um deles correspondendo aos depósitos cársticos, com uma mastofauna mais diversificada e com formas de distintos tamanhos, e outro relacionado aos tanques e ravinas, caracterizado principalmente por formas de grande porte. A tendência para um caráter tafonômico parece ser a explicação mais adequada para as diferenças em composição e diversidade dos restos de mamíferos provenientes dos tanques, em relação àqueles dos depósitos cársticos das cavernas. Nestes, não é possível descartar completamente, além disso, a influência de processos de mistura temporal.
TAPHONOMY OF THE FOSSIL MAMMALS ASSEMBLAGE OF THE "1968 FISSURE", SÃO JOSÉ DE ITABORAÍ BASIN, RIO DE JANEIRO STATE, BRAZIL. Significant amount of taxonomic information has been extracted from fossil mammal assemblages of the São José de... more
TAPHONOMY OF THE FOSSIL MAMMALS ASSEMBLAGE OF THE "1968 FISSURE", SÃO JOSÉ DE ITABORAÍ BASIN, RIO DE JANEIRO STATE, BRAZIL. Significant amount of taxonomic information has been extracted from fossil mammal assemblages of the São José de Itaboraí Basin, located at Rio de Janeiro State, Southeastern Brazil. However, taphonomic analysis, which are important for understanding the formation of these taphocoenosis, are rare and superficial. A limestone fissure excavated in 1968 (here called "1968 Fissure") stands out among the several known fossiliferous concentrations by its abundance of skeletal elements and by the unique brownish color of the specimens, which differentiate them from those collected in other fissures. This study aims to identify and interpret taphonomic features observed in the taphocoenosis "1968 Fissure", which include fractures, abrasion marks, desiccation marks, teeth marks, bone representativeness, and preservational patterns diagnostic for the occurrence and type of transport during the formation of fossiliferous concentration. Based on taphonomic analysis, the mammal taphocoenosis of the "1968 Fissure" is characterized as parautochthonous, being exposed for a short time before being deposited in the fissure after a short transport, possibly triggered by floods. Probably, predators did not influence the formation of the fossil assemblage studied. Only small mammals occur in the fissure due to a possible selection during the bioestratinomic phase. During the fossildiagenetic phase, several fractures were produced in the material due to compression generated by sediment deposition in the fissure. The observed pattern in the skeletal completeness shows the influence of anatomical features of mammals in differential preservation of skeletal remains during the process of fossilization.
Neste trabalho, lâminas petrográficas evidenciam os processos de permineralização por carbonatos de cálcio e de ferro e minerais opacos e de substituição por calcita em fósseis de vertebrados pleistocênicos do Tanque do Jirau, Itapipoca,... more
Neste trabalho, lâminas petrográficas evidenciam os processos de permineralização por carbonatos de cálcio e de ferro e minerais opacos e de substituição por calcita em fósseis de vertebrados pleistocênicos do Tanque do Jirau, Itapipoca, Ceará, Brasil. Elementos químicos de cristais formadores da rocha que compõe o tanque provavelmente contribuíram para a geração dos minerais identificados nos ossos fossilizados. Tal associação de minerais indica um clima úmido após o soterramento desses ossos.
- by Hermínio Araújo-Júnior and +2
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- Taphonomy
Pleistocene vertebrates from Itaboraí Basin have not been taphonomically studied prior to this work, limiting the understanding of the deposition and preservation of the only Pleistocene vertebrate accumulation known for the state of Rio... more
Pleistocene vertebrates from Itaboraí Basin have not been taphonomically studied prior to this work, limiting the understanding of the deposition and preservation of the only Pleistocene vertebrate accumulation known for the state of Rio de Janeiro. In this work, the taphonomic signatures of the Pleistocene vertebrate assemblage of Itaboraí are identified and interpreted in order to increase the knowledge about the formation of this fossil association and the paleoecology of the region of Rio de Janeiro during the late Pleistocene. Our analysis shows that the thanatocoenosis was exposed to the biostratinomic processes during a small time span; that it is parautochthonous; and experienced short transport distances by normal fluvial streams and floods. Subsequently, the fossiliferous horizon was quickly covered by the superjacent soil. Yet, the skeletal elements were fractured and deformed during the sedimentary compaction. The differential preservation of megamammal bones is associated to the bone resistance against those destructive processes and to the specific anatomical features. Comparison between Itaboraí and other Brazilian Pleistocene vertebrate accumulations shows that the Itaboraí fossil accumulation was less affected by taphonomic processes, although it is also a time-averaged fossil concentration. Finally, some of the taphonomic features indicate an arid paleoclimate.
Upper Cretaceous vertebrate accumulations from the Adamantina Formation are known due to their high taxonomic diversity. On the other hand, taphonomic analyses still are rare, limiting the understanding of processes related to the... more
Upper Cretaceous vertebrate accumulations from the Adamantina Formation are known due to their high taxonomic diversity. On the other hand, taphonomic analyses still are rare, limiting the understanding of processes related to the biostratinomic and fossildiagenetic histories of this lithostratigraphic unit. In 2005, fossils were collected from an outcrop located at Jales municipality, state of São Paulo, southeastern Brazil. From this outcrop, a well-preserved Baurusuchus was recovered, which displays a peculiar set of taphonomic signatures. This paper identifies and interprets taphonomic features of a specimen of Baurusuchus (Crocodyliformes, Baurusuchidae; UFRJ DG 418-R) from the Adamantina Formation (Upper Cretaceous of the Bauru Basin), in Jales municipality, state of São Paulo. Brief taphonomic comparisons with other specimens previously studied (crocodiles and dinosaurs) and a lithofaciological analysis of the outcrop were undertaken in order to enhance the knowledge of the stratigraphy and paleoenvironment and improve the time resolution for the Adamantina Formation in the region of Jales. Furthermore, paleoecological data were interpreted based on the taphonomic analysis.
- by Hermínio Araújo-Júnior and +1
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- Paleoecology, Taphonomy, Crocodyliformes, Cretaceous
Fossiliferous natural tanks are a singular type of sedimentary deposit restricted to northeastern Brazil, which usually preserves a diversified late Pleistocene vertebrate fauna. Their fossil assemblages are taxonomically well known, but... more
Fossiliferous natural tanks are a singular type of sedimentary deposit restricted to northeastern Brazil, which usually preserves a diversified late Pleistocene vertebrate fauna. Their fossil assemblages are taxonomically well known, but their taphonomy is poorly understood. This work presents a detailed taphonomic analysis of a tank deposit from Jirau site (Ceará State, Northeastern Brazil) to improve understanding of the processes that influenced fossil deposition and preservation in natural tanks and to shed light on paleoecological and paleoenvironmental aspects related to the late Pleistocene vertebrate fauna from Northeastern Brazil. Tank deposits from different localities were also compared to figure out potential taphonomic patterns among them. Additionally, comparisons with other Brazilian Pleistocene deposits and other debris-flow deposits bearing vertebrates were undertaken. The study revealed the predominance of the megamammal Eremotherium laurillardi in the deposit, which we attributed to its abundance in late Pleistocene biocoenosis as well as bone resistance. Scarcity of non-mammalian vertebrates is likely related to their paucity in late Pleistocene biocoenosis. Time-averaging was evidenced by the co-occurrence of different weathering, petrographic and color patterns, and may have affected the ontogenetic profile of the accumulation relative to the original biocoenosis. Analyses of weathering stages, tooth and trample marks, indicate wide exposition of the thanatocoenosis before burial. Abrasion and petrographic patterns allow reworking in the assemblage to be inferred. Permineralization and substitution are the fossilization processes observed. Taphonomy indicates that floods deposited clasts and bioclasts in the tank under an arid or semiarid climate in a debris-flow regime. Comparison with other tank deposits revealed several similar taphonomic features and differences related to sedimentology and stratigraphy. Taphonomic similarities suggest rather homogeneous environmental conditions in the northeastern Brazil during the late Pleistocene, as previously suggested by taxonomic studies. Comparison with other Brazilian Pleistocene deposits shows that tanks have more temporal fidelity than caves, coastal and some fluvial deposits. The Jirau vertebrate accumulation was produced by the reworking and transport of skeletal elements accumulated in a nearby thanatocoenosis and is similar to other better known debris-flow hosted vertebrate accumulations.
Biological, stratigraphic, and temporal processes act on the origin of fossil concentrations. The influence of these phenomena on fossil vertebrate accumulations from tank deposits recently began to be analyzed in detail. This paper... more
Biological, stratigraphic, and temporal processes act on the origin of fossil concentrations. The influence of these phenomena on fossil vertebrate accumulations from tank deposits recently began to be analyzed in detail. This paper documents taphonomic patterns recognized in the late Pleistocene fossil vertebrate accumulation from a tank deposit of Lage Grande Paleontological Site (LGPS), Pernambuco State, northeastern Brazil. The preservation observed in LGPS differs strongly from the expected for tank accumulations and, given the high quality of preservation and the low rate of time-averaging inferred (indicated by the low degrees of surface bone modifications), it seems reasonable that LGPS accumulation reflects nearly non-biased biocenotic patterns. Under this hypothesis, Eremotherium laurillardi was the most abundant species in the region of Lage Grande during the late Pleistocene, similarly to other areas with tank deposits. Surprisingly, cingulates were rare or absent. Non-mammalian vertebrates and Glossotherium were rare in that area. Taphonomic signatures indicate that the thanatocoenosis of Lage Grande experienced a short time span of subaerial exposure prior to burial and short transport to inside the tanks by debris-flows. Thus, LGPS accumulation can be classified as parautochthonous. Besides the inferred rapid burial of the LGPS assemblage, when compared to other tank accumulations, another feature that may had generated the peculiar taphonomic setting of LGPS accumulation is the uncommon pond-like morphology of this deposit. Morphology of the tanks may be one additional factor responsible for differential preservation of vertebrates in this kind of deposit.
Paleopathological analyses of Brazilian Quaternary mammals remain scarce. However, this type of study can shed light on several paleoecological issues in vertebrate paleobiology and taphonomy. Here, we describe and diagnose a pathology on... more
Paleopathological analyses of Brazilian Quaternary mammals remain scarce. However, this type of study can shed light on several paleoecological issues in vertebrate paleobiology and taphonomy. Here, we describe and diagnose a pathology on an axis of a ground sloth Eremotherium laurillardi (Lund, 1842) from Pernambuco State, Brazil. Through the identification of osteophytes, we define an osteoarthritic lesion in the atlantoaxial joint (C1-C2), which is unrelated to body weight support. Thus, this paper reports a peculiar allocation of osteoarthritis in a mammalian skeleton. We did not attribute such alteration to calcium pyrophosphate deposition disease (CPPD) because the bone elevation occurs only on the borders of the lateral articular facets of the axis, and not on the joint surface. This analysis shows that osteoarthritis can also occur in regions of vertebral column that are not weight-bearing, which is one of the main predisposing factors for this disease.