An expanded Smithian–Spathian (Lower Triassic) boundary from a reefal build‐up record in Oman: implications for conodont taxonomy, high‐resolution biochronology and the carbon isotope record

Some 2.7 myr after the Permian–Triassic boundary mass extinction, a stepwise extinction of the nekton (ammonoids and conodonts) ended at the Smithian–Spathian boundary (SSB) during an episode of climate cooling. SSB records from continental shelves are usually affected by an unconformity, suggesting a forced regression of glacioeustatic origin. Here, we document a new 30-m-thick SSB section from Jebel Aweri (Batain Plain, Oman) that provides an exceptionally complete and expanded record preserved in an exotic block. Most of this SSB section consists of microbial boundstone build-ups with a framework of metazoan bioclasts that formed in shallow water on an offshore seamount. In Wadi Musjah (Hawasina nappes, Oman), another exotic block records the SSB in a deeper water setting represented by Hallstatt-type facies. These two sections provide a unique perspective on the early Spathian rapid re-diversification of conodonts. They led to a thorough revision of conodont taxonomy around the SSB and to the construction of the highest resolution biochronological scheme for this time interval in the Tethys. A total of five SSB sections from Oman representing both offshore seamounts and lower slope deposits were included in a high-resolution, quantitative unitary associations (UA) analysis. The resulting 8 conodont biozones are intercalibrated with ammonoid zones and with the carbonate carbon isotope record ultimately placing the SSB in the interval of separation between UAZ3 and UAZ4. Only the association of Novispathodus pingdingshanensis with Icriospathodus crassatus can be used to unambiguously characterize the base of the Spathian. Key words: Oman, Smithian, Spathian, conodont, Early Triassic, unitary association

Contribuição à Zooarqueologia do Sambaqui do Moa: novos vestígios ictiológicos

This paper presents the description and a brief discussion on the ichthyologic remains recovered from excavations in Moa’s Shellmound, located in Saquarema/RJ. There are 39 otoliths belonging to the taxa: Cynoscion sp., Micropogonias furnieri, Pogonias cromis and Genidens genidens, and 9 shark teeth of the genus Carcharhinus, Galeocerdo, Sphyrna, Carcharias and Isurus, these unprecedent even for the located area. And from these recordings, it was possible to verify paleoenvironment considerations, and the use of these fishes within the culture of the shellmound populations.Este trabalho apresenta a descrição e uma breve discussão sobre os vestígios icitológicos recuperados a partir de escavações realizadas no Sambaqui do Moa, localizado em Saquarema/RJ. Eles são 39 otólitos, pertencentes aos taxa: Cynoscion sp., Micropogonias furnieri, Pogonias cromis e Genidens genidens, e 9 dentes de tubarões dos gêneros Carcharhinus, Galeocerdo, Sphyrna, Carcharias e Isurus, inéditos até então para o sítio. A partir desses registros, foi possível verificar informações referentes ao paleoambiente e à utilização desses peixes para a cultura dos povos sambaquieiros

Padrões ecológicos de tubarões (Superordem: Selachimorpha) fósseis e recentes obtidos a partir de isótopos estáveis e suas considerações para manejo e conservação

Sharks populations are declining drastically in many parts of the world, demanding new complementary approaches for the comprehension of biological characteristics. Amplifying the temporal range of investigation to the Miocene past (23 Ma), this research had as objective interpret ecological features from extant and fossil sharks by the way of stable isotopes measurements of carbon and oxygen, looking to generate intellectual basis for management and conservation plans. In total, 46 teeth of several localities were utilized, most are from the coastal region of eastern Amazonia, but also from proto-Caribbean fossiliferous deposits. Isotopic analysis were employed in the distinct bioapatites structures: carbonate and phosphate, where the enameloid was preferentially uptaken in the samples to reduce possibilities of collect unoriginal chemical signatures. A tooth file analyzed from extant specimens exhibited strong correlations among the involved variables (carbon and oxygen), potentially signaling an isotopic fractionation effect in the carbonate structure varying in accordance with tooth development. Oxygen in phosphate results ranged between 18,9‰ to 21.4 ‰, indicating paleotemperatures where these animals lived around 21,6°C to 30,6°C. Statistical tests were performed in the observed values, allowing the discrimination of three groups: Pirabas group (fossil sharks of Pirabas Formation) Recent group (extant sharks of the Amazon coastal region) and non-Pirabas group (fossil sharks of proto-Caribbean deposits). Global, regional and biological environmental considerations about these individuals were revised to understand their distinct chemical signatures. Oceanographic influences and changes in planetary patterns seem to justify some peculiarities of the measures found in non-Pirabas group. On the other hand, the ecological stability verified comparing the paleotemperatures of the Pirabas group with the Recent group suggests resilience on the part of these sharks, by maintaining similar ecological niches during geological time in the Amazon region. However, it also implies a biological preference for swimming in specific conditions for a better physiological performance. The ecological pattern of activity proposed for the sharks of the northern Brazil (23°C-30°C), in addition to paleointerferences about the group here realized should be incorporated in future plans of management and conservation of elasmobranchs, as they reinforce the existing scientific knowledge concerning this táxon.CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorTubarões sofrem declínios de volume em numerosas partes do globo, necessitando cada vez mais de metodologias complementares para a compreensão de seus traços biológicos. Ampliando o espectro de análise desses parâmetros para o passado, esta pesquisa teve como objetivo interpretar as características ecológicas de tubarões atuais e fósseis através da análise de isótopos estáveis de carbono e oxigênio, visando gerar subsídios para ações de conservação biológica. No total, 46 dentes de diversas localidades foram utilizados, em sua maioria oriundos da zona costeira da região Amazônica, mas também provenientes de depósitos fossilíferos proto-Caribenhos. Empregaram-se análises isotópicas na estrutura do carbonato e fosfato destas bioapatitas e preferencialmente o enamelóide foi amostrado para reduzir possibilidades de contaminação nas amostras. Uma fileira de dentes analisada de um grupo recente exibiu fortes correlações entre as variáveis envolvidas (carbono e oxigênio), potencialmente sinalizando a existência de um fracionamento isotópico na estrutura do carbonato em consonância com o crescimento dentário. Os resultados do oxigênio no fosfato variaram entre 18,9‰ até 21,4‰, indicando paleotemperaturas onde estes animais habitaram de 21,6°C a 30,6°C. Através de testes estatísticos, três grupos distinguiram-se a partir dos valores observados: grupo Pirabas (tubarões fósseis da Formação Pirabas), grupo Recente (tubarões extantes da região costeira Amazônica) e grupo não-Pirabas (tubarões fósseis proto-Caribenhos). Considerações ambientais globais, regionais e biológicas destes indivíduos foram levantadas para compreender estas distintas assinaturas químicas. Influências oceanográficas e mudanças nos padrões planetários parecem justificar a peculiaridade das medidas encontradas no grupo não-Pirabas. Por outro lado, estabilidade ecológica verificada comparando as paleotemperaturas do grupo Pirabas com o grupo Recente sugere a resiliência do grupo em manter nichos de atuação similares durante o tempo geológico na região Amazônica. Entretanto, também insinua sua preferência em nadar dentro de condições específicas para obter um melhor desempenho fisiológico. O padrão ecológico de atuação proposto para os tubarões da Região Norte (23°C-30°C), além das paleointerpretações aqui realizadas a respeito do grupo devem ser incorporadas na elaboração de planos de manejo e conservação, pois reforçam o conhecimento científico existente sobre este táxon

Characterizing conodont bioapatite from the Early-Triassic: an analytical and palaeoclimatological approach

The Early Triassic (252 to 247 Ma) was a dramatic period for life on Earth. This time range follows the Permian-Triassic boundary mass extinction (PTBME), the most catastrophic biotic crisis on Earth. This episode is thought to have been triggered by the consequences of magmatic activity associated with the Siberian Traps volcanism, which added significant levels of greenhouse gases into the atmosphere. For this reason, early assumptions were that the ecological recovery during the Early Triassic was delayed for all organisms. However, recent contributions have characterized it as a succession of short-term recovery-extinctions cycles, controlled by climatic oscillations as well as regional environmental variations. A major intra-Triassic extinction at the Smithian–Spathian boundary (SSB) was noted to be even larger in magnitude for secondary consumers compared to the PTBME. Studies of biotic crises in the geological past are important to understand, such that we can also better estimate the impacts that Earth’s natural system may be facing in view of future climatic and environmental changes. To complement the palaeoclimatic perspective about this period, this thesis investigated conodont bioapatites through stable oxygen isotope measurements (δ18O), used as proxies to estimate palaeoenvironmental conditions and relative sea water temperature changes. While conodonts are widely used biogenic archives for tracing changes in palaeoclimatic/environmental conditions, they are sadly very small in size and often only occur in low abundances in some critical sections that might be useful for palaeoclimatic/environmental interpretations. Hence, this thesis examined the possibility of using only a few conodonts for a representative analysis of their oxygen isotope composition. In particular, the SIMS (Secondary Ion Mass Spectrometry) analytical approach was critically examined for biogenic phosphates in general. Questions on the microstructure and chemical distribution in conodonts and shark teeth were studied to establish routine analytical protocols that would aim at ultimately using only a number of individual specimens in order to get representative and precise analysis. Through micro-analytical techniques, we noted the influence of sample preparation and of analysing different bioapatite tissues in the SIMS results. As such this first part then opened up the possibility of studying specimens also from sections that only contain rare conodonts but that are of critical importance for an improved, global interpretation of changing climatic and environmental conditions in the past. The second part of this thesis involves in-situ δ18O analysis in Omani conodonts from two exotic carbonate blocks: one from a condensed section with low sedimentation rates and abundant specimens recovered per layer; and one from a time-equivalent, well-preserved extended section, where conodonts are only rarely found. The new oxygen isotope measurements from these two comparative sections did improve our knowledge about the progression of the climatic upheavals covering the Smithian–Spathian Boundary (SSB). In the third part, results from different sections around the globe are compared, ranging from low to high palaeolatitudes and from both palaeo-oceans of the Early Triassic: the Tethys and Panthalassa. The findings of this chapter highlight differences in conodont oxygen isotope compositions recovered from distinct settings, and enhance the knowledge about the palaeo-oceanography and -circulation, the palaeosalinity and the local controls on different sections studied in the comparison, allowing for a more detailed view on global changes in palaeoenvironmental conditions and changes thereof. Being part of a major SNF-funded project, the Mid-Early Triassic Extreme Climatic Oscillation (METECO) project, the products of this thesis should both complement future interpretations about the Early Triassic climatic context and contribute with quantifications of climatic changes

Neogene Caribbean elasmobranchs: diversity, paleoecology and paleoenvironmental significance of the Cocinetas Basin assemblage (Guajira Peninsula, Colombia)

The Cocinetas Basin is located on the eastern flank of the Guajira Peninsula, northern Colombia (southern Caribbean). During the late Oligocene through the Pliocene, much of the basin was submerged. The extensive deposits in this area suggest a transition from a shallow marine to a fluvio-deltaic system, with a rich record of invertebrate and vertebrate fauna. The elasmobranch assemblages of the early Miocene to the late Pliocene succession in the Cocinetas Basin (Jimol, Castilletes and Ware formations, as well as the Patsúa Valley) are described for the first time. The assemblages include at least 30 taxa of sharks (Squaliformes, Pristiophoriformes, Orectolobiformes, Lamniformes and Carcharhiniformes) and batoids (Rhinopristiformes and Myliobatiformes), of which 24 taxa are reported from the Colombian Neogene for the first time. Paleoecological interpretations are based on the feeding ecology and on estimates of the paleohydrology (relative salinity, temperature) using stable isotope compositions of oxygen in the bioapatite of shark teeth. The isotopic composition of the studied specimens corroborates paleoenvironmental settings for the studied units that were previously estimated based on the sedimentology and biology of the taxa. These Neogene elasmobranch assemblages from the Cocinetas Basin provide new insights into the diversity the sharks and rays inhabiting the coastal and estuarine environments of the northwestern margin of South America, both during the existence of the gateway between the Atlantic and Pacific oceans and following its closure

A bone to pick: stable isotope compositions as tracers of food sources and paleoecology for notosuchians in the Brazilian Upper Cretaceous Bauru Group

Notosuchia is a highly diverse group of crocodyliforms that peaked during the Cretaceous period. Their taxonomic abundance and morphological disparity in the Upper Cretaceous Bauru Group (Bauru Basin, Brazil) is remarkable, with over 20 species reported. The stable carbon and oxygen isotope composition of notosuchian bioapatite from two sites (i.e., the Ponto 1 do Price and Fazenda Três Antas) in west Minas Gerais State was analyzed to evaluate differences in feeding habits among the taxa found in both localities. Possible environmental stressors are examined, in parallel to sedimentological, paleopedological, and paleontological studies, which indicate a semi-arid to arid climate for the Bauru Group. Multiple tissues of notosuchian crocodyliforms were included in our study, as well as a testudines carapace fragment, lepisosteiform fish teeth and scales, and host rocks. The mineral textures, X-ray diffraction and stable isotope data support preservation of tooth enamel and scale ganoin bioapatite. The δ13C results point to different feeding habits between two terrestrial, carnivore notosuchians, namely a terrestrial source diet for Uberabasuchus terrificus and an aquatic source diet for Campinasuchus dinizi. The δ18Ow for the crocodyliform data was calculated and compared to other Upper Cretaceous sites. Values support dry conditions during the formation of the bioapatite for the Fazenda Três Antas site and point to the Hateg Basin in Romania, yet likely younger, as a good paleoclimatic analogue.Fil: Klock, Carolina. University of Ghent; BélgicaFil: Leuzinger, Léa Sylvia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; ArgentinaFil: Miloni Santucci, Rodrigo. Universidade do Brasília; BrasilFil: Martinelli, Agustín Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Marconato, André. Universidade de Sao Paulo; BrasilFil: Marinho, Thiago S.. Universidade Federal Do Triàngulo Mineiro; BrasilFil: Luz, Zoneibe. Universite de Lausanne; SuizaFil: Vennemann, Torsten Walter. Universite de Lausanne; Suiz

Contributions to Moa´s Shellmound: fish microfossils analysis

This study is the presentation of the material from fish microfossils collected in Moa�s Shellmound, located in Saquarema, Rio de Janeiro state. The new use of two associated techniques: the flotation and re-screening using different granulometric sizes, allowed the recovery of 1662 Euteleostean microteeth, in fossilization process by substitution. These were initially separated into nine types, which will be used in future for more refined taxonomic descriptions. Thus, contributing to increased information about the Moa�s Shellmound, considered an important indicators of prehistoric fishermen populations who inhabited the brazilian coast.CONTRIBUCIÓN A LA ZOOARQUEOLOGÍA DEL SAMBAQUI DE MOA/RJ: ANALISIS DE MICROVESTÍGÍOS DE PECES. Este trabajo es la presentación del material de micro vestigios de pescados recolectados en el Sambaqui do Moa, ubicado en Saquarema, en la provincia de Rio de Janeiro. La utilización inédita de dos técnicas asociadas: la de flotación y retamización utilizando granulometrías diferenciadas, lo que posibilitó la recuperación de 1662 micro dientes de Euteleostei, en proceso de fosilización por sustitución. Estos fueron separados inicialmente en nueve tipos que serán utilizados futuramente para descripciones taxonómicas más esmerada. Contribuyendo, así, con el aumento de informaciones acerca del Sambaqui do Moa, considerado un importante indicio de las poblaciones de pescadores prehistóricos que habitaron el litoral brasileño.CONTRIBUIÇÕES A ZOOARQUEOLOGIA DO SAMBAQUI DO MOA/RJ: ANÁLISE DE MICROVESTÍGIOS DE PEIXES. Este trabalho é a apresentação do material de microvestígios de peixes coletados no Sambaqui do Moa, localizado em Saquarema, estado Rio do Janeiro. A utilização inédita de duas técnicas associadas: a de flotação e repeneiragem utilizando granulometrias diferenciadas possibilitou a recuperação de 1662 microdentes de Euteleostei, em processo de fossilização por substituição. Estes foram separados inicialmente em nove tipos que serão utilizados futuramente para descrições taxonômicas mais refinadas. Contribuindo, assim, com o aumento de informações a cerca do Sambaqui do Moa, considerado um importante indício das populações de pescadores préhistóricos que habitaram o litoral brasileiro

Life and reproduction of titanosaurians: Isotopic hallmark of mid-palaeolatitude eggshells and its significance for body temperature, diet, and nesting

Eggshells represent an important part of the fossil record of Titanosauria (Dinosauria – Neosauropoda) and their stable isotope compositions are valuable palaeoenvironmental proxies. A new set of conventional (δ18O and δ13C) and clumped (Δ47) stable isotope compositions of titanosaurian eggshells is presented, together with that of a bone and a single associated tooth, sampled in three Late Cretaceous nesting sites from La Rioja Province, NW Argentina. The preservation state of the fossils was first evaluated using optical and analytical techniques, such as transmitted light and optical cathodoluminescence (CL) microscopy, energy dispersive X-ray spectroscopy (EDX), and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). The isotopic compositions of the fossils were then compared to those of associated carbonate rocks and nodules, hydrothermal calcite and quartz, and those reported for eggshells from other nesting sites worldwide. This large, combined sample set allows us to define an isotopic hallmark (δ13CVPDB = − 15 to − 11‰; δ18OVSMOW = 27 to 33‰) typical for wellpreserved mid-palaeolatitude titanosaurian eggshells. This hallmark is intended to identify the oological specimens best suited for palaeoenvironmental reconstructions, for instance in museum collection samples that may lack associated abiogenic materials such as host rocks. In addition, our isotopic data support that titanosaurians were animals with an elevated body temperature, mainly feeding on C3 plants, and reproducing under conditions more arid than the long-term average. The data are in excellent agreement with the isotopic data reported from other mid-palaeolatitude nesting sites around the world, indicating that titanosaurians needed similar environmental conditions to reproduce, regardless of the palaeogeographic location of their habitat. Finally, we raise the question whether titanosaurians experienced reproduction-related fasting, as noted for several extant vertebrates, and discuss the complexity of interpreting Δ47-derived temperatures, despite very consistent bulk isotopic data.Fil: Leuzinger, Léa Sylvia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de Catamarca. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Secretaría de Industria y Minería. Servicio Geológico Minero Argentino. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Provincia de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; ArgentinaFil: Bernasconi, Stefano Michele. Eidgenössische Technische Hochschule Zürich; SuizaFil: Vennemann, Torsten Walter. Universite de Lausanne; SuizaFil: Luz, Zoneibe. Universite de Lausanne; SuizaFil: Vonlanthen, Pierre. Universite de Lausanne; SuizaFil: Ulianov, Alexey. Universite de Lausanne; SuizaFil: Baumgartner Mora, Claudia. Universite de Lausanne; SuizaFil: Hechenleitner, Esteban Martín. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de Catamarca. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Secretaría de Industria y Minería. Servicio Geológico Minero Argentino. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Provincia de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; ArgentinaFil: Fiorelli, Lucas Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de Catamarca. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Secretaría de Industria y Minería. Servicio Geológico Minero Argentino. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Provincia de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; ArgentinaFil: Alasino, Pablo Horacio. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Rioja; Argentin