O naturalista dinamarquês Peter Wilhelm Lund (1801-1880), considerado o pai da Paleontologia brasileira, professava a chamada Teoria do Catastrofismo, de Georges Cuvier. Foi para tentar comprovar esta teoria que o naturalista escavou milhares de fósseis nas cavernas de Lagoa Santa (MG) entre 1835 e 1844, quando descreveu dezenas de espécies extintas do período Pleistoceno. Durante este trabalho, Lund descobriu os esqueletos fossilizados de cerca de 30 seres humanos, que ficaram conhecidos como os Homens de Lagoa Santa. Logo após esta descoberta, o naturalista enviou suas coleções para a Dinamarca e pôs um fim nos trabalhos de campo, sem no entanto voltar ao seu país e permanecendo no Brasil até sua morte. <br />A maior questão não respondida sobre a vida de Peter Lund, e o objetivo deste trabalho, é entender porque afinal ele parou de pesquisar? O próprio Lund alegou falta de dinheiro. Mas seus biógrafos escolheram como bode espiatório o cansaço físico e intelectual após anos de trabalho ininterrupto nas cavernas. <br />A resposta, no entanto, encontra-se na coleção de cartas de Lund, arquivadas na Biblioteca Real de Copenhagen. O presente trabalho é resultado do estudo de uma pequena parte desta correspondências. Analisou-se a vida do naturalista à luz da sua relação com a família, mestres e amigos no Brasil e na Dinamarca, na esperança de identificar a razão para o término das pesquisas de um dos mais influentes cientistas do Brasil no século XIX.

Arthropods have a rich fossil record spanning the Phanerozoic. Biomineralized forms such as the extinct trilobites are particularly common and are proven index fossils for biostratigraphy. Forms with an unmineralized cuticle are more rare, preserved only in so called konservat lagerstätten. Cambrian strata of Greenland have yielded rich trilobite faunas with potential for intercontinental correlation of Cambrian strata, but also an exceptionally preserved fauna, the Sirius Passet Lagerstätte. The first part of this thesis is concerned with trilobite biotratigraphy of the provisional Cambrian Series 2 in Greenland. The second part is concerned with exceptionally preserved arthropods from the Sirius Passet Lagerstätte, but also from 'Orsten' deposits from the Cambrian of Sweden. Perissopyge phenax occurs in the Henson Gletscher and Paralleldal formations spanning the Series 2 and 3 boundary interval in North Greenland. It also occurs in the Sekwi Formation of Yukon Territory, demonstrating that the species may hold potential for correlation within Laurentia. An indeterminate species of Perissopyge is shown to occur in the Ella Island Formation of North-East Greenland together with Olenellus cf. hanseni, which is similar to Olenellus cf. truemani described from the Henson Gletscher Formation. If this correlation is further corroborated it would offer a first tie-point for the An t'Sron Formation of North-West Scotland which yields Fritzolenellus lapworthi, herein reported for the first time from the Bastion Formation which underlies the Ella Island Formation. Oelandocaris oelandica from ‘Orsten’ deposits in the Cambrian series 3 and 4 boundary interval in Sweden is an early representative of the Crustacean stem lineage. Kiisortoqia avannaarsuensis is a new arthropod from the Sirius Passet Lagerstätte with robust antennulae strikingly similar to the 'raptorial' limb of the problematic anomalocaridids. The ventral morphology of the 'bivalved' Isoxys volucris is described for the first time and compared with other species assigned to Isoxys from Cambrian lagerstätten around the world. Finally, Siriocaris trolla, is a new arthropod that similarities with trilobites and certain ‘trilobitomorphs’ but seems to lack important synapomorphies of these taxa, though this may be due to preservational limitations in the material at hand.

The Pachycormiformes were a successful group of stem-teleosts. Although they persisted for more than 100 million years in the Mesozoic seas and occupied a significant space of the ecosystem, little is known about this most diverse group. One of the earliest pachycormiformes is the lower Jurassic Pachycormus bollensis. A reconstruction of the phylogeny with the early P. bollensis together with more derived and earlier studied species has yielded important information about the relationships within the group. Both a parsimony analysis and a Bayesian analysis were performed. Three exceptionally complete specimens of P. bollensis from the Holzmaden-locality were used for the study. The resulting trees strongly supported pachycormiform monophyly. Three major ecomorphological clades were returned from the analyses: the filter-feeders, hyper carnivores and a more generalist predator radiation that included P. bollensis. Despite, node support within the pachycormiformes are generally weak. The tooth-structure and the phylogenetic position of P. bollensis might indicate an intermediate grade between the filter-feeders and the hyper carnivores. / Pachycormiformer var en mycket framgångsrik ordning utav stam-teleoster. Trots att de överlevde i mer än 100 miljoner år i de Mesosoiska haven och erövrat ett flertal olika platser i ekosystemet, är denna mågfacetterade grupp som helhet tämligen okänd. Pachycormus bollensis från yngre jura är en av de tidigste arterna i denna grupp. En fylogenetiskt rekonstruktion av den tidiga P. bollensis tillsammans med yngre, mer utvecklade arter kan ge viktig information om släktskapen inom gruppen. En parsimonisk analys och en Bayesian analys utfördes. Tre exceptionellt bevarade exemplar av Pachycormus bollensis från Holzmaden användes i studien. Resultatet visar på ett stark monofyletiskt sammanband inom pachycormiformerna. Båda analyserna visade robusta resultat för tre övergripande grupper; filtrerare, karnivorer och en mer generell predator linje som inkluderar P.  bollensis. Dock hade de interna släktskapen inom varje större grupp svagt stöd. Tand-stukturen tillsammans med den fylogenetiska placeringen av P. bollensis kan tyda på en intermediär grupp mellan filterarna och karnivorerna.

No description available.

No description available.

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.

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.

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.