O conhecimento acerca dos invertebrados devonianos no Brasil teve início em fins do século XIX e a primeira metade do século XX, período no qual foram feitas expedições pioneiras às principais bacias paleozoicas do país - as bacias do Paraná, Parnaíba e Amazonas. Desta fase também resultaram importantes trabalhos científicos (e.g., Clarke, 1913), usados ainda hoje como referência em estudos. Dentre os trilobitas, os grupos mais representativos são os Homalonotidae e os Calmoniidae, cuja importância como ferramentas em questões paleoambientais e paleobiogeográficas vem sendo constatada a partir de recentes revisões sistemáticas em fósseis da Bacia do Paraná. Estes estudos também têm demonstrado que muitas das variações nos fósseis, interpretadas por pesquisadores anteriores como taxonômicas, decorrem de alterações tafonômicas, que podem levar a classificações errôneas. Neste contexto, o presente trabalho teve como objetivos revisar a sistemática dos trilobitas Phacopida (Homalonotidae e Calmoniidae) nas bacias do Parnaíba e Amazonas, incluindo, na primeira localidade, a nova ocorrência de São João Vermelho, no município de João Costa (PI), investigar, sempre que pertinente, a implicação das alterações tafonômicas na sistemática desses fósseis, identificando fatores diagenéticos/intempéricos que podem interferir nos caracteres morfológicos e discutir as implicações paleobiogeográficas dos Homalonotidae e Calmoniidae do Devoniano das bacias do Amazonas e Parnaíba, em relação a outras localidades adjacentes à estas bacias. Resultados das pesquisas mostram que a localidade de São João Vermelho é bastante promissora do ponto de vista paleontológico, pois consiste em uma nova localidade para o táxon M. tuberculatus, o qual também é documentado nas duas subbacias da Bacia do Paraná - Alto Garças e Apucarana, indicando que esta espécie apresenta alto grau de cosmopolitanismo. A análise de exemplares de Burmeisteria (Homalonotidae) desta localidade sugere que as diferenças nas espécies deste gênero no Brasil são mais sutis do que imaginado. Na Bacia do Amazonas, os Phacopida estão representados especialmente por Calmoniidae do gênero Malvinella, também presentes na Bolívia. As relações paleobiogeográficas entre as bacias paleozoicas brasileiras e a Bolívia, durante o Eo e Mesodevoniano, teriam sido mais estreitas do que se imaginava. A principal rota de migração para a Bacia do Parnaíba teria sido através da Bacia do Paraná, conforme constatado pela presença de M. tuberculatus. Já a migração para a Bacia do Amazonas teria se dado a sudoeste desta bacia, já que Malvinella ocorre apenas nesta bacia e na Bolívia / The knowledge on Brazilian Devonian invertebrates started by the end of the 19th century and the first half of the 20th century, period which pioneering expeditions were made to the main Paleozoic basins of the country - Paraná, Parnaíba and Amazon basins. Important scientific contributions also resulted from this fase (e.g. Clarke, 1913), still used today as reference in studies. Among trilobites, the most representative groups are the Homalonotidae and Calmoniidae, whose importance in paleoenvironmental and paleobiogeographical questions have been noted from recent systematic revisions in Paraná Basin fossils. These studies also have demonstrated that many variations in fossils, interpreted by previous researchers as taxonomic, are due to taphonomic alterations, which can lead to erroneous classifications. In this context, the current study aimed to review the systematics of Phacopida trilobites (Homalonotidae and Calmoniidae) from the Parnaíba and Amazon basins, including, in the former locality, the new occurrence of São João Vermelho, in the João Costa municipality (PI); to investigate, whenever relevant, .the implication of the taphonomic alterations in the systematics of these fossils, identifying diagenetic/weathering factors which can interfere in the morphological features; and to discuss the paleobiogeographic implications of the Homalonotidae and Calmoniidae from the Devonian of the Parnaíba and Amazon basins, in relation to other localities adjacent to these basins. Study results show that the locality of São João Vermelho is paleontologically promising, as it consists of a new place for the M. tuberculatus taxon, which is also documented in the both Paraná Basin subbasins - Alto Garças and Apucarana, indicating that this species is highly cosmopolitan. The analysis of Burmeisteria (Homalonotidae) exemplars from this locality suggests that differences between the species of this genus in Brazil are slighter than thought. In the Amazon Basin, Phacopida trilobites are especially represented by the Calmoniidae genus Malvinella, also present in Bolivia. The paleobiogeographic relations between the Paleozoic Brazilian basins and Bolivia, during Early and Middle Devonian, would have been closer than thought. The main migration route to the Parnaíba Basin would have been through the Paraná Basin, as found by the presence of M. tuberculatus. The migration to the Amazon Basin, in turn, would have occurred southwestward this basin, as Malvinella occurs only in this locality and in Bolivia.

The acanthodians were a common and widespread group of fishes throughout the world during the mid-Palaeozoic. In this study, a full-scale systematic analysis of Silurian to Middle Devonian acanthodian taxa of eastern Australia was undertaken, incorporating a review and updating of historical records and descriptions of taxa. Phylogenetic relationships within the group and with other early gnathostomes are uncertain. The structure, function and modes of growth of acanthodian scales were described and investigated, and these features were used for comparisons between different taxa within the group, and between acanthodians and other early vertebrates. Histological and morphological characters of the scales were incorporated in a cladistic analysis of genera erected for articulated fish. This analysis did not support the traditional ordinal level groups, the Climatiida, Ischnacanthida and Acanthodida. Therefore, the highest taxonomic level used in the study was the family. Rarely were acanthodians preserved as articulated fossils. The only examples known from the Silurian-Middle Devonian of Australia are one specimen of the putative acanthodian Yealepis douglasi Burrow & Young 1999 from the Ludlow of Victoria, five specimens of an indeterminate ?ischnacanthidid from the late Givetian of New South Wales and a rich assemblage from the Givetian lacustrine shales of Mt Howitt, Victoria. The latter fauna (originally dated as Late Devonian) includes six incomplete specimens of the culmacanthidid Culmacanthus stewarti Long 1983 and about 60 specimens of acanthodidid Howittacanthus kentoni Long 1986. In contrast, disassociated remains of the group are ubiquitous in microvertebrate faunas from the mid-Palaeozoic of eastern Australia. Although scales of other fish groups are sometimes more common in particular facies, acanthodian elements are found in all depositional environments, from deep shelf marine to transitional to freshwater. Most of the taxa, particularly those only preserved as isolated scales, had not been systematically described by other workers. This thesis incorporates descriptions of new taxa, and revision and updating of other taxa. Several overseas studies have produced biostratigraphic charts based on acanthodian scales. A similar biostratigraphic overview was undertaken based on a systematic analysis of the Early Devonian acanthodians of eastern Australia, permitting comparisons with acanthodian faunas of other regions. Acanthodian scales and fin spines are the most common elements in the few vertebrate faunas that are known from the Silurian of Australia. Diversity and geographic distribution of the acanthodian faunas peaked during the Early Devonian. This study has been hampered by the low numbers of scales in many samples, and by uncertainty over their dating (particularly for the faunas from non-limestone deposits). Nevertheless, the work shows that changes in the marine assemblages are broadly correlated with the pattern of marine transgressions and regressions. Composition of the acanthodian faunas, and their abundance relative to other vertebrates in the assemblages, depend on the depositional environment. This correlation is best illustrated in Lower Devonian deposits, in which acanthodians are the most prolific and diverse. In transitional and marginal marine deposits, thelodonts are dominant, and acanthodians a minor element of the fauna. In off-shore assemblages, acanthodians and placoderms are dominant, and thelodonts are rare or absent. Vertebrate faunas are poor in the earliest Devonian deposits, but become more common by the late Lochkovian, with near-shore assemblages characterized by Trundlelepis cervicostulata and ANostolepis@ guangxiensis, and deeper shelf assemblages by a new genus, possibly assignable to the Ischnacanthidae. The vertebrate record is sparse through the middle Pragian, though AN.@ guangxiensis is present low in the Coopers Creek Limestone (upper sulcatus-pireneae zones), being replaced by Nostolepoides platymarginata, Gomphonchus? bogongensis, and Radioporacanthodes sp. aff. R. (Gomphonchus) liujingensis by the kindlei Zone. Microvertebrate assemblages are more common by the late Pragian (pireneae Zone), with Radioporacanthodes sp. aff. R. liujingensis in deeper shelf deposits, and N. platymarginata and G.? bogongensis dominating near-shore assemblages. The earliest Emsian (dehiscens Zone) is marked by the incoming Cheiracanthoides wangi. Middle Emsian (perbonus-serotinus zones) assemblages are characterized by two new species, possibly assignable to Gomphonchus.The Middle Devonian cosmopolitan association of Cheiracanthoides comptus and AAcanthoides@ dublinensis, which characterizes early Middle Devonian faunas from North America, Europe and China, appears first in the latest Emsian at the serotinus-patulus zone boundary. As well as showing the value of acanthodians in biostratigraphy and as indicators of environmental settings, their use in biogeography was demonstrated. Although many of the acanthodian taxa are endemic, several are also found in other regions. The Silurian to earliest Devonian faunas of eastern Australia are most closely related to coeval Chinese assemblages. Several latest Silurian-earliest Devonian taxa are also recorded from the circum-Arctic region. The late Lochkovian to early Emsian assemblages, particularly from south-eastern Australia, have many taxa in common with Chinese faunas. The mid-Emsian taxa show highest endemicity; and the latest Emsian-Eifelian assemblages have the most cosmopolitan aspect. Acanthodian faunas become rarer and depauperate in the Middle Devonian, particularly in the south-eastern corner, and are mostly in poorly dated, ?fluviatile/marginal marine deposits. This study of acanthodian faunas has encompassed a full scale systematic review of the group in this region, an appraisal of phylogenetic relationships within the group and with other early vertebrates, their palaeoecology, and their use in biostratigraphy and biogeography.

The acanthodians were a common and widespread group of fishes throughout the world during the mid-Palaeozoic. In this study, a full-scale systematic analysis of Silurian to Middle Devonian acanthodian taxa of eastern Australia was undertaken, incorporating a review and updating of historical records and descriptions of taxa. Phylogenetic relationships within the group and with other early gnathostomes are uncertain. The structure, function and modes of growth of acanthodian scales were described and investigated, and these features were used for comparisons between different taxa within the group, and between acanthodians and other early vertebrates. Histological and morphological characters of the scales were incorporated in a cladistic analysis of genera erected for articulated fish. This analysis did not support the traditional ordinal level groups, the Climatiida, Ischnacanthida and Acanthodida. Therefore, the highest taxonomic level used in the study was the family. Rarely were acanthodians preserved as articulated fossils. The only examples known from the Silurian-Middle Devonian of Australia are one specimen of the putative acanthodian Yealepis douglasi Burrow & Young 1999 from the Ludlow of Victoria, five specimens of an indeterminate ?ischnacanthidid from the late Givetian of New South Wales and a rich assemblage from the Givetian lacustrine shales of Mt Howitt, Victoria. The latter fauna (originally dated as Late Devonian) includes six incomplete specimens of the culmacanthidid Culmacanthus stewarti Long 1983 and about 60 specimens of acanthodidid Howittacanthus kentoni Long 1986. In contrast, disassociated remains of the group are ubiquitous in microvertebrate faunas from the mid-Palaeozoic of eastern Australia. Although scales of other fish groups are sometimes more common in particular facies, acanthodian elements are found in all depositional environments, from deep shelf marine to transitional to freshwater. Most of the taxa, particularly those only preserved as isolated scales, had not been systematically described by other workers. This thesis incorporates descriptions of new taxa, and revision and updating of other taxa. Several overseas studies have produced biostratigraphic charts based on acanthodian scales. A similar biostratigraphic overview was undertaken based on a systematic analysis of the Early Devonian acanthodians of eastern Australia, permitting comparisons with acanthodian faunas of other regions. Acanthodian scales and fin spines are the most common elements in the few vertebrate faunas that are known from the Silurian of Australia. Diversity and geographic distribution of the acanthodian faunas peaked during the Early Devonian. This study has been hampered by the low numbers of scales in many samples, and by uncertainty over their dating (particularly for the faunas from non-limestone deposits). Nevertheless, the work shows that changes in the marine assemblages are broadly correlated with the pattern of marine transgressions and regressions. Composition of the acanthodian faunas, and their abundance relative to other vertebrates in the assemblages, depend on the depositional environment. This correlation is best illustrated in Lower Devonian deposits, in which acanthodians are the most prolific and diverse. In transitional and marginal marine deposits, thelodonts are dominant, and acanthodians a minor element of the fauna. In off-shore assemblages, acanthodians and placoderms are dominant, and thelodonts are rare or absent. Vertebrate faunas are poor in the earliest Devonian deposits, but become more common by the late Lochkovian, with near-shore assemblages characterized by Trundlelepis cervicostulata and ANostolepis@ guangxiensis, and deeper shelf assemblages by a new genus, possibly assignable to the Ischnacanthidae. The vertebrate record is sparse through the middle Pragian, though AN.@ guangxiensis is present low in the Coopers Creek Limestone (upper sulcatus-pireneae zones), being replaced by Nostolepoides platymarginata, Gomphonchus? bogongensis, and Radioporacanthodes sp. aff. R. (Gomphonchus) liujingensis by the kindlei Zone. Microvertebrate assemblages are more common by the late Pragian (pireneae Zone), with Radioporacanthodes sp. aff. R. liujingensis in deeper shelf deposits, and N. platymarginata and G.? bogongensis dominating near-shore assemblages. The earliest Emsian (dehiscens Zone) is marked by the incoming Cheiracanthoides wangi. Middle Emsian (perbonus-serotinus zones) assemblages are characterized by two new species, possibly assignable to Gomphonchus.The Middle Devonian cosmopolitan association of Cheiracanthoides comptus and AAcanthoides@ dublinensis, which characterizes early Middle Devonian faunas from North America, Europe and China, appears first in the latest Emsian at the serotinus-patulus zone boundary. As well as showing the value of acanthodians in biostratigraphy and as indicators of environmental settings, their use in biogeography was demonstrated. Although many of the acanthodian taxa are endemic, several are also found in other regions. The Silurian to earliest Devonian faunas of eastern Australia are most closely related to coeval Chinese assemblages. Several latest Silurian-earliest Devonian taxa are also recorded from the circum-Arctic region. The late Lochkovian to early Emsian assemblages, particularly from south-eastern Australia, have many taxa in common with Chinese faunas. The mid-Emsian taxa show highest endemicity; and the latest Emsian-Eifelian assemblages have the most cosmopolitan aspect. Acanthodian faunas become rarer and depauperate in the Middle Devonian, particularly in the south-eastern corner, and are mostly in poorly dated, ?fluviatile/marginal marine deposits. This study of acanthodian faunas has encompassed a full scale systematic review of the group in this region, an appraisal of phylogenetic relationships within the group and with other early vertebrates, their palaeoecology, and their use in biostratigraphy and biogeography.

Tristichopterids (Sarcopterygii, Tetrapodomorpha) form a monophyletic group of exclusively Devonian fishes. This thesis consists of descriptions of new material of tristichopterids and closely related taxa, as well as new interpretations and descriptions of previously figured material. Redescribed specimens were originally figured as far back as 1861, and publications as old as this are almost always of limited use as anatomical and systematical references, in addition to being difficult to acquire. The possibility of using new techniques and new theoretical frameworks also provides good justification for taking a second look at such specimens. In the case of this thesis, this includes the use of computed tomography scanning methods, and the cladistic approach to describing the interrelationships of taxa. The thesis includes a complete taxonomy of valid tristichopterid taxa, in addition to two new phylogenetic analyses incorporating the taxa that were described or redescribed. One of the analyses deals with the interrelationships of taxa along the entire tetrapod stem, and establishes the monophyly of the Tristichopteridae. The other analysis focuses on tristichopterid interrelationships. An account is given of evolutionary trends within Tristichopteridae, and instances of parallel evolution between tristichopterids and other tetrapodomorph groups are discussed. The biogeographical implications of tristichopterid occurences world-wide seem to corroborate the picture provided by other vertebrate groups, and give further support to one of two main hypotheses concerning the relative positions of Gondwana and Laurussia, the two major palaeocontinents during the Late Devonian. The supported hypothesis proposes a close proximity between southern Laurussia and northwestern Gondwana, as evidenced by the wide dispersal of derived tristichopterids by the Late Devonian. A Laurussian origin of tristichopterids is proposed.

Ctenoconularia deiphiensis,is a new species of the Conulata based on a population of specimens from a phosphatic nodular sandstone at the base of the New Albany Shale (Upper Devonian) at Delphi,Indiana.The transverse ridges possess interridge furrows with bead-like nodes that are not structurally continuous with the ridges. The ridges are altered into four elongate pustules upon crossing the interfacial groove.Ball State UniversityMuncie, IN 47306

Thesis (M.E. Des.)--University of Calgary, 2000. / Includes bibliographical references.

Carbonate facies patterns and stratal architecture are the product of the complex interaction of internal (e.g., reef-building biota, sediment production) and external drivers (e.g., tectonics, climate, and relative sea level). In the Canning Basin of Western Australia, many of these drivers are in flux across the Late Devonian Frasnian--Famennian (F--F) boundary and significant variations in reefbuilding biota and long-term accommodation are observed. This study documents the evolution of the Canning Basin's Devonian reef complexes across the F--F boundary and proposes a new interpretation of the stratal architecture and paleobathymetric profile of the Famennian. Data presented here demonstrate the evolutionof a shelf-crest system in the Famennian, with beds expanding basinward and the reef growing in water depths of approximately 5-15 m. The paleobathymetric profile of the Famennian described by this study represents a departure from the well-documented barrier-reef system of the Frasnian. Digital outcrop models help capture the heterogeneity of the Famennian system and allow for characterization of the Devonian reef complexes across the F--F boundary. Syndepositional fractures are a ubiquitous feature of high-relief, reefrimmed carbonate systems and these features exert a profound influence on many facets of platform evolution. This study documents strong variability in syndepositional fracture patterns as a function of lithofacies and depositional setting and evidence for the temporal evolution of the mechanical properties of the Devonian reef complexes is presented. A statistically significant relationship is documented between syndepositional fracture development and variations in stratigraphic architecture, approximated here by platform-margin trajectory. This relationship implies a significant stratigraphic control on syndepositional deformation in carbonate platforms and suggests that external drivers are not required to generate early fractures in high-relief carbonate platforms.

No description available.

No description available.

No description available.