Quatro associações faunísticas de tetrápodes são conhecidas para o Triássico Médio/Superior do Rio Grande do Sul, pertencendo à Supersequência Santa Maria. A Cenozona de Santacruzodon (Sequência Santa Maria 1; Carniano) é a segunda delas, da base para o topo, reconhecida, inicialmente, no município de Santa Cruz do Sul e contendo quase que exclusivamente cinodontes traversodontídeos (Traversodontidae), com quatro morfótipos preliminarmente descritos, e um cinodonte chiniquodonídeo. Posteriormente, um dos morfótipos foi nomeado como Santacruzodon hopsoni, e também foram reconhecidos para esta unidade bioestratigráfica o cinodonte carnívoro cf. Probainognathus e o proterocâmpsio Chanaresuchus bonapartei. Mais recentemente, o morfótipo tipo I foi reconhecido como pertencendo a Menadon besairiei, táxon registrado apenas na Formação Isalo II, em Madagascar. Os novos materiais brasileiros de Menadon, que são descritos no artigo integrante desta Dissertação de Mestrado, incluem um crânio praticamente completo e diversas mandíbulas, e confirmam o reconhecimento desta espécie de cinodonte traversodontídeo para a Cenozona de Santacruzodon. A identificação foi feita baseada na morfologia sincraniana e dentária: crânio alto na região do rostro, presença de quatro incisivos superiores, I1 e I2 procumbentes, três incisivos inferiores, todos procumbentes, baixo número de pós-caninos de formato quadrangular, último pós-canino inferior reduzido, maxila excluída da margem da fenestra sub-orbital pelo jugal, processo angular do dentário projetado posteriormente. A presença de M. besairiei na Supersequência Santa Maria além de incrementar o conhecimento da distribuição e riqueza dos traversodontídeos no Gondwana, também acarreta em consequências bioestratigráficas importantes, confirmando a correlação entre a fauna de Isalo II e a da Cenozona de Santacruzodon, as quais também compartilham cinodontes proximamente relacionados, como massetognatíneos (Dadadon isaloi e Santacruzodon hopsoni) e chiniquodontídeos (Chiniquodon kalanoro e chiniquodontídeo indeterminado). / Four tetrapod fossil assemblages are known in the Middle-Upper Triassic of Rio Grande do Sul state, belonging to the Santa Maria Supersequence. The Santacruzodon Assemblage Zone (Santa Maria 1 Sequence, Carnian) is the second from the bottom to top, initially documented in the city of Santa Cruz do Sul, it is composed almost entirely of traversodontid cynodonts (Traversodontidae), from which four morphotypes were preliminarly described, plus one chiniquodontid cynodonts. Further studies described one of the morphotypes as Santacruzodon hopsoni, reported the carnivorous cynodont cf. Probainognathus and the proterochampsid archosauromorph Chanaresuchus bonapartei. More recently, the morphotype I was recognized as belonging to species Menadon besairiei, previously known only from the Isalo II beds of Madagascar. The new Brazilian material of Menadon are described in the research article included in this Master Thesis, it includes a praticaly complete skull and several lower jaws, and they confirm the presence of this species of traversodontid cynodonts in the Santacruzodon Assemblage Zone. The identification was based on cranial and dental morphology: deep snout; four upper incisors; I1 and I2 procumbent; three lower incisors, all procumbent; low postcanine count; quadrangular-shaped postcanines; last lower postcanine reduced in size; maxilla excluded of the suborbital fenestra by the the jugal; posteriorly projected angular process of the dentary. The occurrence of M. besairiei in the Santa Maria Supersequence, in addition to incrementing the knowledge of distribution and diversity of the traversodontids in Gondwana, also produces important biostratigraphical consequences, permitting the correlation between the faunas of Isalo II and Santacruzodon AZ, which hold closely related cynodonts, both Massetognathinae (Dadadon isaloi and Santacruzodon hopsoni) and Chiniquodontidae (Chiniquodon kalanoro and indeterminate chiniquodontid).

Quatro associações faunísticas de tetrápodes são conhecidas para o Triássico Médio/Superior do Rio Grande do Sul, pertencendo à Supersequência Santa Maria. A Cenozona de Santacruzodon (Sequência Santa Maria 1; Carniano) é a segunda delas, da base para o topo, reconhecida, inicialmente, no município de Santa Cruz do Sul e contendo quase que exclusivamente cinodontes traversodontídeos (Traversodontidae), com quatro morfótipos preliminarmente descritos, e um cinodonte chiniquodonídeo. Posteriormente, um dos morfótipos foi nomeado como Santacruzodon hopsoni, e também foram reconhecidos para esta unidade bioestratigráfica o cinodonte carnívoro cf. Probainognathus e o proterocâmpsio Chanaresuchus bonapartei. Mais recentemente, o morfótipo tipo I foi reconhecido como pertencendo a Menadon besairiei, táxon registrado apenas na Formação Isalo II, em Madagascar. Os novos materiais brasileiros de Menadon, que são descritos no artigo integrante desta Dissertação de Mestrado, incluem um crânio praticamente completo e diversas mandíbulas, e confirmam o reconhecimento desta espécie de cinodonte traversodontídeo para a Cenozona de Santacruzodon. A identificação foi feita baseada na morfologia sincraniana e dentária: crânio alto na região do rostro, presença de quatro incisivos superiores, I1 e I2 procumbentes, três incisivos inferiores, todos procumbentes, baixo número de pós-caninos de formato quadrangular, último pós-canino inferior reduzido, maxila excluída da margem da fenestra sub-orbital pelo jugal, processo angular do dentário projetado posteriormente. A presença de M. besairiei na Supersequência Santa Maria além de incrementar o conhecimento da distribuição e riqueza dos traversodontídeos no Gondwana, também acarreta em consequências bioestratigráficas importantes, confirmando a correlação entre a fauna de Isalo II e a da Cenozona de Santacruzodon, as quais também compartilham cinodontes proximamente relacionados, como massetognatíneos (Dadadon isaloi e Santacruzodon hopsoni) e chiniquodontídeos (Chiniquodon kalanoro e chiniquodontídeo indeterminado). / Four tetrapod fossil assemblages are known in the Middle-Upper Triassic of Rio Grande do Sul state, belonging to the Santa Maria Supersequence. The Santacruzodon Assemblage Zone (Santa Maria 1 Sequence, Carnian) is the second from the bottom to top, initially documented in the city of Santa Cruz do Sul, it is composed almost entirely of traversodontid cynodonts (Traversodontidae), from which four morphotypes were preliminarly described, plus one chiniquodontid cynodonts. Further studies described one of the morphotypes as Santacruzodon hopsoni, reported the carnivorous cynodont cf. Probainognathus and the proterochampsid archosauromorph Chanaresuchus bonapartei. More recently, the morphotype I was recognized as belonging to species Menadon besairiei, previously known only from the Isalo II beds of Madagascar. The new Brazilian material of Menadon are described in the research article included in this Master Thesis, it includes a praticaly complete skull and several lower jaws, and they confirm the presence of this species of traversodontid cynodonts in the Santacruzodon Assemblage Zone. The identification was based on cranial and dental morphology: deep snout; four upper incisors; I1 and I2 procumbent; three lower incisors, all procumbent; low postcanine count; quadrangular-shaped postcanines; last lower postcanine reduced in size; maxilla excluded of the suborbital fenestra by the the jugal; posteriorly projected angular process of the dentary. The occurrence of M. besairiei in the Santa Maria Supersequence, in addition to incrementing the knowledge of distribution and diversity of the traversodontids in Gondwana, also produces important biostratigraphical consequences, permitting the correlation between the faunas of Isalo II and Santacruzodon AZ, which hold closely related cynodonts, both Massetognathinae (Dadadon isaloi and Santacruzodon hopsoni) and Chiniquodontidae (Chiniquodon kalanoro and indeterminate chiniquodontid).

Um esqueleto parcialmente completo e semi-articulado de um rauissuquídeo, proveniente de níveis pertencentes à Cenozona de Therapsida (Mesotriássico) da Formação Santa Maria, foi coletado em 2003, no município de Dona Francisca, RS, Brasil. Neste espécime, os ossos do crânio e mandíbula estavam quase todos desarticulados e puderam ser retirados isoladamente da rocha. Tal forma de preservação possivelmente seria uma evidência de que os ossos do crânio deste animal poderiam apresentar mobilidades entre si. Para verificar tal hipótese, foram utilizadas como metodologias tomografias computadorizadas e programas específicos de manipulação digital em três dimensões com o objetivo de criar modelos animados que permitissem o estudo das possibilidades de movimento entre os ossos do crânio deste exemplar de maneira isolada e integrada em todo o crânio. Como resultado, vídeos animados, simulando as possibilidades de movimento entre os ossos do crânio foram gerados e, para cada elemento craniano tomografado, um arquivo em 3D contendo o modelo de sua superfície foi elaborado. Este material foi preparado para publicação em uma revista eletrônica (i.e. Palaeontologia electronica) que permite a exposição e divulgação de conteúdos digitais animados. Os resultados apresentados neste estudo indicaram um número maior de evidências que favorecem um tipo passivo de cinetismo craniano, sendo elas: - movimentos restritos, porém possíveis, entre vários ossos intracranianos; e, - a presença de contatos frouxamente ligados, incapazes de realizar movimentos amplos ou incapazes de realizar qualquer tipo de movimento quando o crânio como um todo é considerado. Apesar disso, mais estudos referentes à reconstrução de tecidos moles e ao desenvolvimento ontogenético de rauissuquídeos são necessários para se testar ou falsear a hipótese de um possível modelo de cinetismo craniano ativo. / Partially disarticulated skull bones of an unidentified rauisuchid were found in Dona Francisca, south Brazil (Therapsid Cenozone, Mesotriassic). The skull bones and mandible of this specimen were almost all disarticulated and could be isolated from the rock separately. This peculiar type of preservation may probably be an evidence of possible intracranial mobility. To verify this hypothesis, computer tomography (CT) scan and specific 3D software methodologies were used to analyse suture morphology and articulation areas of each individual pair of adjacent bones and for an integrated mechanical model, which considered all bones that comprises the skull of the studied specimen. As results, illustrative 3D animations for each discussed videos that simulated possible mobility between skull bones were generated and, a 3D surface model of each CT scanned skull element. Illustrative 3D animations for each discussed movements were created and 3D surface model files for each CT scanned skull element are presented. This material was prepared to be submitted in an electronic journal (i.e. Palaeontologia Electronica), where animated digital documents could be published. As results, this study presented more evidences in favour of passive cranial kinesis, which includes: -restricted, but possible mobility between a considerable number of bones; and, -presence of loosely contacts that would not be able to do extensive movements or would present no mobility at all when the integrated model is considered. Though, more studies on soft tissue reconstructions and ontogenetic development of rauisuchids are needed to testify or falsify the hypothesis of an active cranial kinesis.

The rocks of the Upper Triassic Nicola Group represent the altered broken remnants of a volcanic island archipelago. About 23,000 feet of Upper Triassic sediments and volcanic rock are present in the thesis area. The group is the product of two cycles of deposition distinguishable on the basis of relative abundance of phenocrysts in the volcanic members. Rocks of the lower cycle (P), characterized by abundant feldspar phenocrysts, are separated into a lower, 6,000 foot thick assemblage of flows, breccias, and tuffs composed mainly of basaltic andesite; and an upper, heterogeneous, 8,000 foot thick assemblage composed of andesitic and rarer basaltic or dacitic agglomerates, breccias, tuffs, flows, and associated sediments as well as coral reef bodies. Rocks of the upper cycle (A), characterized by abundant augite phenocrysts, are separated into a lower assemblage about 7,500 feet thick composed of flows, breccias, tuff, and greywacke with rare limestone; and an upper assemblage about 1,600 feet thick composed of tuff, argillites, and cherts. During the Lower Jurassic, the group was gently folded, variably fractured, and intruded by a sequence of plutons culminating in the near-surface emplacement of huge batholiths. Metamorphism and metasomatism associated with batholiths altered the rocks so that they are now composed of low-grade metamorphic mineral assemblages. By mid-Mesozoic time, the plutons were exposed and a conglomerate laid down. Faulting along previous zones of weakness affected area during late Mesozoic time. Eocene deposits formed in an environment of hills and swamps. By late Miocene, after some jostling of faults blocks, the main topographic features of the Interior Plateau were fixed. Subsequent outpouring of Plateau and Valley basalts as well as glacial erosion and deposits have only mildly affected the main topographic features. The Nicola Group provides a chapter on the evolution of the Cordillera. The relationships provide certain limits to events that occurred outside the thesis area. Equally, relationships within the thesis area cannot all be answered without reference to larger areas. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

The Sibiel Shear Zone is a 1-3km wide, ductile shear zone located in the South Carpathian Mountains, Romania. In the Rsinari area, the ductile shear zone juxtaposes amphibolite facies rocks of the Lotru Metamorphic Suite against greenschist facies rocks of the Rauorul Cisndioarei Formation. The first represents the eroded remnants of Peri-Gondwanan arcs formed between the Neoproterozoic-Silurian (650-430Ma), regionally metamorphosed to amphibolite facies during the Variscan orogeny (350-320Ma). The second is composed of metasedimentary and metavolcanic Neoproterozoic-Ordovician (700-497Ma) assemblages of mafic to intermediate bulk composition also resembling an island arc metamorphosed during the Ordovician (prior to similar to 463Ma). Between these lie the epidote amphibolite facies mylonitic and ultramylonitic rocks of the Sibisel Formation, a tectonic melange dominated by mafic actinolite schists attenuated into a high strain ductile shear zone. Mineral Rb-Sr isochrons document the time of juxtaposition of the three domains during the Permian to Early Triassic (similar to 290-240Ma). Ductile shear sense indicators suggest a right lateral transpressive mechanism of juxtaposition; the Sibiel shear zone is a remnant Permo-Triassic suture between two Early Paleozoic Gondwanan terranes. A zircon and apatite U-Th/He age transect across the shear zone yields Alpine ages (54-90Ma apatite and 98-122Ma zircon); these data demonstrate that the exposed rocks were not subjected to Alpine ductile deformation. Our results have significant implications for the assembly of Gondwanan terranes and their docking to Baltica during Pangea's formation. Arc terranes free of Variscan metamorphism existed until the Early Triassic, emphasizing the complex tectonics of terrane amalgamation during the closure of Paleotethys.

The end–Triassic mass extinction event (ca. 201 Myr ago) has received particular attention over recent decades since Sepkoski (1981) classified it as one of the ‘‘big five’’ biotic crises in Earth's history. In the geological record of Greenland and Sweden, 80% of the species of terrestrial plants disappeared at this boundary. In the last two centuries, Triassic–Jurassic plant remains from Skåne, southern Sweden, have been collected, curated, and studied. However, the paleoflora from the lowermost part of the Helsingborg Member (Lower Jurassic: Hettangian) is poorly understood. Here, a taxonomic study is presented of two novel plant assemblages collected from the Boserup beds (basal Hettangian) in NorraAlbert Quarry, Skåne. The exposures in Skåne are among the few localities in the world that record the terrestrial ecosystem aftermath of the end–Triassic extinction event. Plant macrofossils were studied using macrophotography and fluorescence microscopy. The flora is composed of sphenophytes(Neocalamites), ferns (Cladophlebis, Eboracia), ginkgophytes (Czekanowskia, Pseudotorellia,Ginkgoites), and conifers (Pityophyllum, Brachyphyllum). These earliest Jurassic assemblages were deposited in floodplain environments and revealed a relatively low diversity of flora in the aftermath of the end-Triassic extinction but a fast recovery later. Additionally, the flora was compared with the relative lowermost Jurassic beds in East Greenland, Poland, and Germany, disclosing that ginkgophytes were widely distributed across the northern region of Pangea.

No description available.

Published detrital zircon geochronological data was compiled to form the Global Detrital Zircon Database (GDZDb). This database provides a reference block for provenance analysis by future detrital zircon geochronological studies. This project entailed three subprojects: 1. crustal growth/crustal recycling patterns, 2. a provenance study of the Triassic Dry Fork Formation of the Danville-Dan River Rift basin of Virginia and North Carolina, and 3. sample size issues in detrital zircon studies. The global detrital zircon age frequency distribution exhibits six prominent, statistically significant peaks: 3.2-3.0, 2.7-2.5, 2.0-1.7, 1.2-1.0, 0.7-0.5, and 0.3-0.1 Ga. These peaks are also observed when the data is sorted for continent of origin, the tectonic setting of the host sediment and for modern river sediments. Hf isotope model ages were also incorporated into the database where grains were dated with both U-Pb and Hf isotopes. The Hf isotope model ages suggest that the majority of detrital zircons U-Pb ages reflect crustal recycling events that generated granitic magmatism, as most grains exhibited Hf isotope ages that are much older than the corresponding U-Pb age. The Triassic Dry Fork Formation was sampled from a site in southern Virginia in the Danville-Dan River Basin. The detrital zircon age frequency distribution for this formation was strongly unimodal with a peak at 400-450 Ma and a paucity of Grenville-age zircons. Comparison of the Dry Fork sample to published east coast data and to the North American record (from the GDZDb) illustrate the unusual nature of the Dry Fork Formation sample. It is probable that older Grenville zircons were blocked from the rift valley by the rift shoulder. Using the GDZDb a study of sample size was conducted in order to estimate the best sample size to use when trying to constrain the maximum age of sedimentation of the host sediment. Rift basins and active margins exhibited smaller offsets from the youngest zircon grain age to host sediment maximum age than observed in samples from passive margins. This study recommends that at least 50 grains need to be age dated on average in order to best constrain the age of the host sediment. / Ph. D.

The Triassic Period (~252–201.5 Ma) saw a transformative radiation and reorganization of continental tetrapod diversity following the end-Permian Extinction, including an assemblage of diverse forms that do not survive the end-Triassic (herein termed the 'endemic Triassic fauna', =ETF), as well as the earliest fossil representatives of all major modern tetrapod groups (herein termed the 'Living [Triassic to Recent] Fauna', =LTF; i.e. Salientia, Caudata, Gymnophiona, Mammaliaformes, Squamata, Rhynchocephalia, Testudinata, Crocodylomorpha, and Dinosauria). With few exceptions, only the LTF assemblage survives the end-Triassic Extinction (~201.5 Ma), highlighting the Late Triassic (~227–201.5 Ma) record as essential for understanding this pivotal transition and the evolutionary and ecological origins of post-Triassic non-marine tetrapod faunas, including those of present day. Micro-microvertebrate bonebeds are arguably the best proxy for tracking continental vertebrate biodiversity, however gaps in their Late Triassic record obscure patterns and drivers of evolutionary, ecological, and environmental change during the rise of LTF communities. In my dissertation, I use new data collected from Upper Triassic microvertebrate bonebeds from North America, and particularly the Thunderstorm Ridge site (PFV 456) in Petrified Forest National Park, Arizona, U.S.A, to fill gaps in the evolutionary record of specific groups (e.g., lissamphibians and lepidosaurs), as well as the vertebrate paleocommunity record of Triassic equatorial Pangaea. My first chapter describes and analyzes an assemblage of gymnophionomorph (stem caecilian) bones from PFV 456 which represent the oldest-known caecilian fossils globally. As the oldest caecilian fossils, they provide new support for the dissorophoid temnospondyl affinities of caecilians and other living amphibians, evidence of a step-wise acquisition of caecilian anatomies associated with fossoriality, and evidence of an ancient pattern of equatorial biogeographic restriction in caecilians from the Triassic to the present day. My second chapter describes and analyzes an assemblage of lepidosauromorphs from the Late Triassic of Equatorial Pangaea, providing new insights into the step-wise evolution tooth and jaw morphologies near the divergence of living lepidosaur clades (Squamata and Rhynchocephalia), and showing evidence for the Triassic acquisition in stem squamates and non-squamate lepidosaurs of dental features conserved in living squamates. The third chapter uses apomorphy-based identifications to describe the vertebrate diversity of the Thunderstorm Ridge site (PFV 456), providing evidence for the most species rich continental vertebrate community yet-known from the Triassic, with 55 vertebrate taxa. Nearly all LTF clades are present, predating similar assemblages from the early Jurassic by over 20 million years, and indicating that the assembly of the first LTF communities by at least 220 million years ago, long before the Triassic-Jurassic Extinction event (~201.5). The presence of this exceptional diversity may be linked to the climatic and environmental settings of equatorial Pangaea during the Triassic. / Doctor of Philosophy / The Triassic Period, lasting about 50 million years from approximately 252 to 201.5 million years ago, was a period of transformation for life living on land. During the Triassic, we see the first fossil evidence for the evolution of the tetrapod (animals with a backbone and limbs) groups familiar to us from the present-day Earth, including frogs, salamanders, caecilians, mammals, lizards, the tuatara, turtles, crocodilians, and dinosaurs. Understanding the early evolution of these groups is limited by gaps in the Triassic fossil record, particularly for groups with small-bodies and delicate skeletons like frogs, salamanders, caecilians, and lizards. The poor Triassic records of these groups also limits understandings of when and where tetrapod communities resembling those of the present-day first assembled, and whether events like the Triassic-Jurassic Extinction event (~201.5 million years ago) shaped the organization of these communities. To fill these gaps, I have focused on collecting data from microvertebrate bonebeds, layers of rock that preserve the small, delicate bones of small-bodied vertebrates that are typically rare elsewhere. New microvertebrate data collected from Late Triassic rocks in North America, and particularly the 220 million year old Thunderstorm Ridge site (PFV 456) in Petrified Forest National Park, Arizona, U.S.A., provide evidence for exceptionally diverse tetrapod communities, opening a window onto the early evolution of living tetrapods and their ecological interactions. In my first chapter I describe and analyze the bones of a stem caecilian amphibian from the Thunderstorm Ridge site. These are the oldest caecilian fossils on Earth, and they provide new evidence for the evolutionary relationships, ecologies, and biogeography of these enigmatic living amphibians. In my second chapter I describe and analyze the jaws and teeth of early lizards and their close relatives from North American Late Triassic microvertebrate sites, showing that the tooth and jaw morphologies of living lizards like geckos and skinks first evolved in their Triassic relatives. In my third chapter, I describe and identify the 55 vertebrate taxa recovered from the Thunderstorm Ridge site, showing that it is the most diverse tetrapod community known from the Triassic. The diversity of early members of living tetrapod groups at Thunderstorm Ridge suggests that tetrapod communities resembling those of the present-day first assembled in the Triassic, at least 20 million years prior to the Triassic-Jurassic Extinction.

<p> A detailed section of the Duck Cove Member (Nadon, 1981) of the Triassic Lepreau Formation of Southern New Brunswick is measured.</p> <p> The section consists of a complex sequence of conglomerates and sandstones with a minor occurrence of mudstones and breccia. A description of the facies is provided and an interpretation is based on observations of ancient and marine braided stream deposits of Miall (1978) and Allen (1983). The Markov chain analysis is used to describe the vertical succession of facies.</p> <p> Paleoflow indicators suggest a flow towards the south or southeast. However this conclusion is based on limited availability of data.</p> / Thesis / Bachelor of Science (BSc)