Dissertations / Theses on the topic 'Reptiles, Fossil'

This project aims to study fossil amphibian and reptile (herpetofaunal) remains from Quaternary sites in the British Isles. This neglected group of vertebrates hold great potential for Quaternary Science. Collectively, they cover a wide range of ecological tolerances, although individual species often have very specific tolerances. The biology and ecology of individual species are discussed (Chapter 2) to facilitate their use in Quaternary palaeoenvironmental reconstructions, and an account of previous work on fossil herpetofaunas is given (Chapter 3). Very little work on fossil herpetofaunas has been carried out in the British Isles, mainly due to a lack of the required osteological expertise. The preparation and study of a modern osteological collection (Chapter 4), for comparative purposes, has therefore constituted a large and essential part of the project. The resulting manual for the identification of fossil herpetofaunal remains, appropriately illustrated with SEMs and hand-drawn figures, is presented (Chapter 5). The difficulties encountered in identifying some taxa are discussed in detail, and points of caution are stressed where necessary.

The genus Kannemeyeria is one of the most important and distinctive taxa of the Triassic dicynodonts. It became the first Triassic dicynodont known to science, and thus forms the benchmark for the comparison of the evolution and morphology of other Triassic dicynodonts. An understanding of this genus forms an integral part of the biozonation of the Beaufort Group, and is pivotal in influencing the interpretation of the evolution, physiology and phylogenetic relationships of the Triassic dicynodonts. This study focuses on the detailed cranial morphology and relationships of the Kannemeyeria, and uses a rigorous morphological investigation as the basis for a meaningful elucidation of the functional and thus physiological aspects of this dicynodont. The descriptions demonstrate that variations related to the skull size, distortion or naturally occurring variation within the genus allow for the synonymy of the formerly recognised species K. latifrons Broom (1898; 1913), K. erithrea Haughton (1915) and K. wilsoni Broom (1937). This conclusion is further supported by the allometric analysis which cannot distinguish the variation observed in the holotypes with that occurring naturally within a growth series. Apart from the large specimen, the other smaller individuals are accommodated in the genus as different ontogenetic stages of the growth series represented by K. simocephalus Weithofer (1888). Several allometric variables show unusual patterns of development, indicating that Kannemeyeria can be subdivided into ontological classes, as juvenile and adult forms, separated from each other by a particular level of development. An age-related threshold level is suggested, and considered to represent an animal reaching sexual maturity. It is consequently proposed that the Kannemeyeria population was, at an age-related level, subdivided into sexually mature and immature groups but remained ecologically homogeneous. Both the descriptions and the allometric analysis of the species K. cristarhynchus Keyser & Cruickshank (1979) clearly indicate that it does not conform to the growth series of K. simocephalus and thus the differences observed between these two taxa are not constrained to size increases. Consequently, the recognition of the species K. cristarhynchus is considered valid. From the observations of the cranial morphology, tested using an allometric analysis, generic and specific diagnoses are constructed for Kannemeyeria and its two African species. Several features of Kannemeyeria are discussed in a functional context. A corrugated hom-covered snout and large caniniform processes are considered to be associated with defence and posturing behaviour. Several features of the braincase also suggest herding behaviour. Kannemeyeria also has a slightly different occipital musculature arrangement than that proposed for many other dicynodonts. Most Kannemeyeria cranial features are related to its masticatory function. From the analysis of masticatory cycle it is clear that the jaw action is described via a single pivot-point, which in Kannemeyeria approached the original, primitive position of the jaw hinge. The vertical orientation of the articulation and this pivot-point ensured that the muscle action during second phase of mastication produced an upward crushing and grinding action instead of the typical fore-and-aft motion of many other dicynodonts. It also meant that the muscle force was at their maximum, and little or no energy was lost to translation of the moment arm at the jaw articulation. Consequently, the Kannemeyeria masticatory cycle was both highly effective and extremely efficient. The morphology, and resultant physiology, of Kannemeyeria skull is considered to represent the innovative foundation for much of the success of many of the later Triassic dicynodonts.

Keichousaurus hui Young, 1958, from the Middle Triassic of Guizhou, China is a small sauropterygian reptile. It has short snout and elongated temporal openings resembling the European pachypleurosaurid Dactylosaurus. Unlike all the other sauropterygians, the parietal opening is anteriorly positioned. The neck is long and flexible. The body is rigid and the bones are pachyostotic. It has two or three sacral vertebrae. The most striking feature of Keichousaurus is its broad ulna. The entire forelimb has the outline of a paddle or an oar, and may have functioned like one. There is noticeable sexual dimorphism, as is the case for Alpine pachypleurosaurids. The growth of the humerus is highly positive allometric, indicating an important role of the forelimb in locomotion. The horizontal orientation of the pectoral girdle indicate that Keichousaurus, as well as other pachypleurosaurids, was not a subaquatic flyer. Instead, a drag-based regime was followed in locomotion. The symmetrical rowing of the forelimbs precludes lateral undulatory movement of the body. However, vertical undulation is theoretically possible. The reassessment of the phylogenetic position of Keichousaurus hui confirmed that it is a member of the monophyletic group Pachypleurosauroidea.

Mixosaurid ichthyosaurs (mixosaurs) are a dominant group of Middle Triassic marine reptiles that was widely distributed in both Tethyan and Panthalassic terranes. They are represented by many excellently preserved specimens from all around the world and have been studied for more than one hundred years. Even so, their morphology is not adequately known. The systematics of mixosaurs is not well understood and their phylogeny has been controversial. The nomination of several Chinese mixosaurs makes the situation even worse. This thesis aims to provide a comprehensive review of Chinese mixosaurs and discuss their phylogenetic relationships. The detailed anatomy of only valid Chinese mixosaurid species Mixosaurus panxianensis is well established in this thesis. Its ontogenetic changes are also noted and a better diagnosis is given. A new morphotype of mixosaurs from a recently discovered fossil Lagerst?tte, the Luoping biota, is described in detail. This morphotype is similar to M. panxianensis but consistent differences are also present. The ecological comparison to M. panxianensis demonstrates that this morphotype represents a new taxon that is different from M. panxianensis. A nearly complete and articulated specimen of Phalarodon atavus from the Middle Triassic Luoping biota, Yunnan, South China is described. This is the first specimen of P. atavus discovered outside the Germanic Basin. The discovery of this specimen demonstrates a cosmopolitan distribution of P. atavus across the whole Tethyan ocean. The new specimen is also the first one preserving the postcranial anatomy of this species, providing the potential to evaluate its swimming ability for the first time. Functional morphology shows that this species is well adapted for a pursuit attack of prey, consistent with the distribution pattern of the species. Tooth crown morphology suggests that P. atavus may prefer externally soft prey such as belemnoids. Mixosaurs are divided into three ontogenetic stages based on the humeral morphology. The juvenile stage is characterized by a textured dorsal humeral shaft surface. The subadult stage is characterized by a smooth humeral shaft in dorsal view with a rugose humeral head. The adult stage is characterized by a smooth humeral head. The consistent presence of the surface texture of ventral humeral shaft is most probably caused by the strong muscle insertion presumably related to the function of steering of the fore fins in mixosaurs. Five morphotypes of Chinese mixosaurs are recognized in this study. Twenty-five more or less new characters are introduced to evaluate the phylogenetic relationships of mixosaurian-like specimens from China. The monophyly of mixosaurs including all studied Chinese morphotypes is well corroborated. Further investigation on the mixosaurs from Monte San Giorgio is recommended to resolve the phylogenetic relationships of mixosaurs.
published_or_final_version
Earth Sciences
Doctoral
Doctor of Philosophy

The cranial anatomy of the basal captorhinid reptile Captorhinikos parvus (Reptilia, Captorhinidae), is reinterpreted here based on analysis of a group of new specimens recovered subsequent to its original diagnosis as well as further analysis of the original specimens utilized in E.C. Olson's original characterization of the species. Structural features inconsistent with the generic description suggest the redefinition of C. parvus as a new genus, Rhodotheratus parvus. Analyses of basal members and selected derived members support the characterization of Rhodotheratus as a distinct taxon.

The Diadectomorpha is a central taxon in understanding the origin and early evolution of amniotes. It is considered a sister taxon to Amniota and is so similar to amniotes that some researchers have placed it within the Amniota itself. This group is composed of three families: the Limnoscelidae, the Tseajaiidae, and the Diadectidae. Being the most basal member of this group, the family Limnoscelidae is especially important in these studies.

L’étude de la composition isotopique de l’oxygène de l’émail des dents de vertébrésconstitue une méthode fiable de reconstitution des paléotempératures, grâce àl’interdépendance entre le δ18O de l’apatite des dents, le δ18O des fluides corporels, del’eau ingérée et la température du milieu. L’amélioration et la miniaturisation des techniquesanalytiques a permis d’augmenter la résolution du signal reconstitué, depuis les variations detempérature sur de grandes échelles de temps jusqu’aux variations saisonnières durant laformation de la dent. Cependant, ces variations du δ18O de la dent ne sont pas uniquementdépendantes des variations de température du milieu, mais peuvent également êtreaffectées par d’autres paramètres climatiques, comme la répartition des précipitations aucours de l’année, ou biologique, comme le mode de minéralisation de la dent, l’alimentation,la physiologie de l’animal ou des migrations.Les paramètres biologiques peuvent être estimés dans le cas de taxons possédantdes parents proches dans la faune actuelle. Par exemple, la connaissance des processus deformation et de minéralisation des dents de bovinés actuels permet d’interpréter le signalisotopique de l’oxygène enregistré dans les dents de bovinés fossiles. Ainsi, l’analyse dedents de Bison priscus provenant de l’aven de Coudoulous (Lot, France) a permis dereconstituer les variations saisonnières de température au cours de l’avant-dernier épisodeglaciaire (MIS 6) au Pléistocène moyen, lorsque la région servait de terrain de chasse àHomo neanderthalensis. Le climat était à cette époque plus froid de 4°C en moyenne, maisavec des saisons nettement plus contrastées. Ainsi, si les températures estivales étaientidentiques aux valeurs actuelles, les températures hivernales étaient plus basses de 6-7°C.En milieu marin, les variations saisonnières de température affectent uniquement leseaux de surface. Les plaques dentaires de myliobatidés, un groupe de raies pélagiquesvivant principalement entre 0 et 100 mètres de profondeur, sont un outil potentiel pourreconstituer la paléosaisonnalité. L’étude de plaques dentaires de Myliobatis et deRhinoptera actuels montre que la composition isotopique des dents de ces animauxenregistre des variations de température et de δ18O des eaux de surface. Ainsi, il est doncpossible de reconstituer les caractéristiques des masses d’eau traversées par l’animal. Cetoutil a également un intérêt paléoécologique car il permet de mettre en évidence d’éventuelscomportements migratoires, comme chez certains myliobatidés actuels. L’étude despécimens d’Aetomylaeus provenant du Pliocène de Montpellier (Hérault, France) montredes températures 5°C plus élevées par rapport aux v aleurs actuelles
The oxygen isotopic composition of the vertebrate tooth enamel is a reliable proxy toreconstruct paleotemperatures based on the dependence of the δ18O of the tooth apatite onthe δ18O of body fluids, on the δ18O of the drinking water, and on the environmentaltemperature. The improvement and the miniaturization of the analytical procedures allowedincreasing the resolution of the reconstructed signal, from paleotemperature variations overgeological times to seasonal variations during the tooth growth. However seasonal variationsof the enamel δ18O do not only depend on temperature variations but can also be influencedby other climatic parameters such as rainfall distribution over the year, or by biological andecological parameters such as tooth mineralization process, diet, physiology or migratorypatterns.Biological parameters can be estimated based on the study of extant relatives inmodern faunas. For example, data on tooth formation and mineralization processes inmodern bovids allow a better understanding of the oxygen isotopic signal recorded in fossilbovid teeth. Thus reconstruction of seasonal variations of temperature during the penultimateglacial episode (MIS 6) has been made possible from the analysis of Bison priscus teethfrom the aven of Coudoulous (Lot, France). Climate was 4°C colder during the middlePleistocene when Europe was still Homo neanderthalensis hunting ground, and seasonswere more contrasted than today. Summer temperatures were similar to modern values, butwinter temperatures were 6-7°C colder.In marine environments, seasonal variations of temperature only affect surfacewaters. Myliobatids are pelagic rays living mostly between 0 and 100 m depth, thus theoxygen isotopic composition of myliobatid dental plates is a potential proxy to reconstruct thepaleoseasonality. The isotopic analysis of modern Myliobatis and Rhinoptera samplesconfirmed that variations of the sea-surface temperature (SST) and the δ18O of seawater arerecorded in the δ18O of myliobatid teeth. Thus it is possible to reconstruct the variations ofseawater temperature during a part of the animal’s life, but it also allows pointing outmigratory patterns in some myliobatid species. Reconstructions of seasonal variations ofSST during the middle Pliocene in Montpellier (Hérault, France) from the δ18O of myliobatiddental plates yielded paleotemperatures 5°C higher than modern values

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
A Serra da Bodoquena apresenta cavernas calcárias, com restos fossilizados da megafauna pleistocênica. Poucos trabalhos foram feitos para a região abordando este tema, até o momento. Neste contexto, a presente dissertação de mestrado teve por objetivos realizar a identificação dos fósseis de vertebrados dos depósitos espélicos e fluviais da região. Em seguida foram feitas as análises tafonômicas no material. O material analisado é constituído por fósseis retirados do leito do Rio Formoso, Gruta das Fadas e Gruta Forever. Os grupos identificados correspondem a Alligatoridae, Mylodontidae, Megatheriidae, Glyptodontidae, Myrmecophagidae, Hominidae, Caviomorpha, Ursidae, Gomphotheriidae, Toxodontidae, Tayassuidae e Cervidae. Para a primeira localidade, as coletas se deram por meio de sucção dos sedimentos do leito do rio, durante obras do Gasoduto Bolívia-Brasil, em 1995. O material analisado apresentou alto grau de fragmentação. Na Gruta das Fadas foram feitas coletas superficiais em 2006, e os fósseis estudados apresentaram diferentes graus de abrasão, alguns ossos menores estando fragmentados, enquanto os maiores estão completos. Muitos estão friáveis, parcialmente permineralizados. Foram observadas preservações de tecidos não resistentes em um fêmur humano. Na Gruta Forever foram realizadas escavações em dois pontos diferentes, com 1 m2 e 2 m2 de áreas respectivamente, atingindo profundidades máximas de 10 cm, com a identificação de fósseis. Os fósseis apresentam alto grau de corrosão química e fragmentação. Parte deste material parece ter sido transportado por enxurradas para o interior da gruta. Possivelmente águas acidificadas, provenientes de chuvas, causaram dissoluções sobre a superfície dos ossos. Todos os fósseis estão permineralizados. Futuramente estudos sobre a História Geológica desta gruta poderão ajudar no entendimento...
The Bodoquena Plateau shows calcareous caves, with fossilized remains of the Pleistocenic Megafauna. Few investigations have been implemented to the region, approaching this subject. In this context the present Master Dissertation intends to identify vertebrate fossils from caves and fluvial deposits from this region. There have been made taphonomics analysis on the materials and evaluated their contexts. These materials are fossils removed from Formoso River, and the caves “Gruta das Fadas” and “Caverna Forever”. The groups identified are Alligatoridae, Mylodontidae, Megatheriidae, Glyptodontidae, Myrmecophagidae, Hominidae, Caviomorpha, Ursidae, Gomphotheriidae, Toxodontidae, Tayassuidae and Cervidae. In the first site the collect were made through suctions of sediments during works of the “Gasoduto Bolivia-Brasil” construction, in 1995. The material analyzed showed high degree of fragmentations. Inside “Gruta das Fadas” were performed surface samplings in 2006, and the fossils studied showed different degrees of abrasions, some small specimens are fragmented and larger are completed. Many are crumbly, few remains not permineralized. Preservations of soft tissues were evidenced in some of these materials, on the human femur, for instance. Inside “Gruta Forever” were made excavations in two different points, with 1m2 and 2m2 areas respectively, achieving maxima depths of 10 cm. The fossils show high degree of chemical corrosion and fragmentation. Some of these materials appears to have been transported through pluvial process inside this cave. Presumably acidified waters, from rains, have caused dissolutions on bones surfaces. All these materials seem completely permineralized. Future studies about Geological History of this cave can help understand its depositional processess. Thus, the knowledge generated from this work... (Complete abstract click electronic access below)

Orientador: Reinaldo José Bertini
Coorientador: Francisco Sekiguchi de Carvalho e Buchmann
Banca: Mirian Liza Alves Forancelli Pacheco
Banca: Paulo Milton Barbosa Landin
Resumo: A Serra da Bodoquena apresenta cavernas calcárias, com restos fossilizados da megafauna pleistocênica. Poucos trabalhos foram feitos para a região abordando este tema, até o momento. Neste contexto, a presente dissertação de mestrado teve por objetivos realizar a identificação dos fósseis de vertebrados dos depósitos espélicos e fluviais da região. Em seguida foram feitas as análises tafonômicas no material. O material analisado é constituído por fósseis retirados do leito do Rio Formoso, Gruta das Fadas e Gruta Forever. Os grupos identificados correspondem a Alligatoridae, Mylodontidae, Megatheriidae, Glyptodontidae, Myrmecophagidae, Hominidae, Caviomorpha, Ursidae, Gomphotheriidae, Toxodontidae, Tayassuidae e Cervidae. Para a primeira localidade, as coletas se deram por meio de sucção dos sedimentos do leito do rio, durante obras do Gasoduto Bolívia-Brasil, em 1995. O material analisado apresentou alto grau de fragmentação. Na Gruta das Fadas foram feitas coletas superficiais em 2006, e os fósseis estudados apresentaram diferentes graus de abrasão, alguns ossos menores estando fragmentados, enquanto os maiores estão completos. Muitos estão friáveis, parcialmente permineralizados. Foram observadas preservações de tecidos não resistentes em um fêmur humano. Na Gruta Forever foram realizadas escavações em dois pontos diferentes, com 1 m2 e 2 m2 de áreas respectivamente, atingindo profundidades máximas de 10 cm, com a identificação de fósseis. Os fósseis apresentam alto grau de corrosão química e fragmentação. Parte deste material parece ter sido transportado por enxurradas para o interior da gruta. Possivelmente águas acidificadas, provenientes de chuvas, causaram dissoluções sobre a superfície dos ossos. Todos os fósseis estão permineralizados. Futuramente estudos sobre a História Geológica desta gruta poderão ajudar no entendimento... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The Bodoquena Plateau shows calcareous caves, with fossilized remains of the Pleistocenic Megafauna. Few investigations have been implemented to the region, approaching this subject. In this context the present Master Dissertation intends to identify vertebrate fossils from caves and fluvial deposits from this region. There have been made taphonomics analysis on the materials and evaluated their contexts. These materials are fossils removed from Formoso River, and the caves "Gruta das Fadas" and "Caverna Forever". The groups identified are Alligatoridae, Mylodontidae, Megatheriidae, Glyptodontidae, Myrmecophagidae, Hominidae, Caviomorpha, Ursidae, Gomphotheriidae, Toxodontidae, Tayassuidae and Cervidae. In the first site the collect were made through suctions of sediments during works of the "Gasoduto Bolivia-Brasil" construction, in 1995. The material analyzed showed high degree of fragmentations. Inside "Gruta das Fadas" were performed surface samplings in 2006, and the fossils studied showed different degrees of abrasions, some small specimens are fragmented and larger are completed. Many are crumbly, few remains not permineralized. Preservations of soft tissues were evidenced in some of these materials, on the human femur, for instance. Inside "Gruta Forever" were made excavations in two different points, with 1m2 and 2m2 areas respectively, achieving maxima depths of 10 cm. The fossils show high degree of chemical corrosion and fragmentation. Some of these materials appears to have been transported through pluvial process inside this cave. Presumably acidified waters, from rains, have caused dissolutions on bones surfaces. All these materials seem completely permineralized. Future studies about Geological History of this cave can help understand its depositional processess. Thus, the knowledge generated from this work... (Complete abstract click electronic access below)
Mestre

Dix familles de lacertiliens (=lézards) ont été reconnues dans le paléogène d’Europe de l'ouest : iguanidae*, agamidae*, gekkonidae, lacertidae, scincidae, cordylidae, anguidae, necrosauridae, varanidae, helodermatidae. La connaissance de la distribution stratigraphique des taxons de lacertiliens permet d'estimer les variations de leur diversité pendant le paléogène. En outre, les apparitions et extinctions de genres et d'espèces sont suivis durant l'éocène et l'oligocène, ce qui nous autorise à proposer une durée de vie moyenne de 5ma pour les espèces et de 10ma pour les genres, valeurs sensiblement supérieures a celles obtenues chez les mammifères. Apres une faune pauvre et difficile à étudier au paléocène s'installe, des le début de l'éocène, une faune riche et diversifiée. Cette faune reste stable au cours de l'éocène. Cependant, les formes de l'éocène inferieur qui témoignaient des relations avec l'Amérique du nord, tendent à devenir moins nombreuses au cours de l'éocène. L'éocène supérieur voit une augmentation de la diversité probablement liée, directement ou indirectement (appauvrissement des faunes de mammifères), a la dégradation climatique de cette époque. Au passage éocène/oligocène, la diversité chute brutalement. Il s'agit d'une crise majeure pour les lacertiliens. Les raisons de ce phénomène sont analysées. Les formes qui avaient franchi la grande coupure ont survécu peu de temps pendant l'oligocène. La diversification des faunes de lacertiliens ne reprend réellement qu’à l'oligocène moyen. L'oligocène montre le développement d'une lignée particulière de lacertien dont l'histoire est probablement liée a l'évolution de l'environnement. Il ne s'agit pas d'une succession de taxons, mais de diversifications successives au sein d'un groupe monophylétique ; le taxon souche se maintient pendant tout l'oligocène. Un test statistique applique à l'espèce (lacerta s. 1. Filholi) confirme que nous sommes en présence d'une stase évolutive

L'étude de la composition isotopique de l'oxygène de l'émail des dents de vertébrésconstitue une méthode fiable de reconstitution des paléotempératures, grâce àl'interdépendance entre le δ18O de l'apatite des dents, le δ18O des fluides corporels, del'eau ingérée et la température du milieu. L'amélioration et la miniaturisation des techniquesanalytiques a permis d'augmenter la résolution du signal reconstitué, depuis les variations detempérature sur de grandes échelles de temps jusqu'aux variations saisonnières durant laformation de la dent. Cependant, ces variations du δ18O de la dent ne sont pas uniquementdépendantes des variations de température du milieu, mais peuvent également êtreaffectées par d'autres paramètres climatiques, comme la répartition des précipitations aucours de l'année, ou biologique, comme le mode de minéralisation de la dent, l'alimentation,la physiologie de l'animal ou des migrations.Les paramètres biologiques peuvent être estimés dans le cas de taxons possédantdes parents proches dans la faune actuelle. Par exemple, la connaissance des processus deformation et de minéralisation des dents de bovinés actuels permet d'interpréter le signalisotopique de l'oxygène enregistré dans les dents de bovinés fossiles. Ainsi, l'analyse dedents de Bison priscus provenant de l'aven de Coudoulous (Lot, France) a permis dereconstituer les variations saisonnières de température au cours de l'avant-dernier épisodeglaciaire (MIS 6) au Pléistocène moyen, lorsque la région servait de terrain de chasse àHomo neanderthalensis. Le climat était à cette époque plus froid de 4°C en moyenne, maisavec des saisons nettement plus contrastées. Ainsi, si les températures estivales étaientidentiques aux valeurs actuelles, les températures hivernales étaient plus basses de 6-7°C.En milieu marin, les variations saisonnières de température affectent uniquement leseaux de surface. Les plaques dentaires de myliobatidés, un groupe de raies pélagiquesvivant principalement entre 0 et 100 mètres de profondeur, sont un outil potentiel pourreconstituer la paléosaisonnalité. L'étude de plaques dentaires de Myliobatis et deRhinoptera actuels montre que la composition isotopique des dents de ces animauxenregistre des variations de température et de δ18O des eaux de surface. Ainsi, il est doncpossible de reconstituer les caractéristiques des masses d'eau traversées par l'animal. Cetoutil a également un intérêt paléoécologique car il permet de mettre en évidence d'éventuelscomportements migratoires, comme chez certains myliobatidés actuels. L'étude despécimens d'Aetomylaeus provenant du Pliocène de Montpellier (Hérault, France) montredes températures 5°C plus élevées par rapport aux v aleurs actuelles.

L'etude systematique, taphonomique, paleoecologique et paleobiogeographique des fossiles de vertebres marins turoniens de la vallee superieure du magdalena, colombie, est presentee. Cette etude correspond au premier travail realise sur l'ensemble des vertebres turoniens de colombie. Le materiel considere comprend 26 specimens d'apres lesquels on reconnait 6 taxons de chondrichthyes, 4 taxons d'osteichthyes, et 4 taxons de reptiles. De ces taxons, 9 etaient inconnus en colombie. Un nouveau genre et deux nouvelles especes de teleosteens sont reconnus. Bien que le registre lithologique indique que les conditions de depot du bassin turonien de colombie etaient essentiellement anoxiques, l'etude paleoecologique des vertebres permet de proposer que la tranche d'eau presentait de bonnes conditions d'oxygenation. Ces conditions ont permis le developpement d'une chaine trophique du necton bien structuree, certainement soutenue par de grandes masses de plancton. Une large connexion du bassin avec l'ocean permettait probablement l'entree de courants riches en nutriments, ainsi que de vertebres pelagiques. Les fossiles etudies presentent une excellente conservation en trois dimensions. L'analyse taphonomique permet de proposer que des evenements anoxiques ont pu provoquer des mortalites subites du necton et que les restes ont ete deposes et enfouis a proximite du lieu de mort des organismes. Ils ont subi une lente decomposition sur le fond du bassin, sous conditions anoxiques. Les vertebres etudies representent apparemment un ensemble faunique developpe isolement dans la region nord-ouest de l'amerique du sud. Au niveau supra-specifique on peut pourtant observer des affinites, d'une part avec les faunes de l'ouest de l'afrique et, d'autre part, avec les faunes du nord de l'afrique et du sud de l'europe centrale. Ces faunes apparemment nouvelles en colombie, et en partie aussi dans le monde, semblent etre des faunes de recouvrement liees a la crise cenomano-turonienne.

A Dissertation submitted to the Faculty of Science University of the Witwatersrand, .Johannesburg for the Degree of Master of Science.
A detailed morphological study of two skulls of Emydops was undertaken by using the serial grinding technique. Graphical, wax modeI and computer-3D reconstructions of various aspects of the skulls were made. The internal structures are described in detail and compared to other small dicyncdonts such as Eodicmodort, Pristerodon, Tropidostpma, Cistecepnalus and Diictodon. The structure of the skull of Emydops conforms within the limits of variation known for this genus, to descriptions given in the literature. It was found that Emydops is different from other dicynoconts in that the parasphen and has a definite suture with the pterygoid anterior to the pterygoidbasisphenoid suture, which is not noticed and mentioned for other dicynodonts, except for Emydops (Olson, 1944).
Andrew Chakane 2018

A dissertation submitted to the Faculty of Science, University of Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science.
Dinocephalians form an important part of the Upper Permian therapsid faunas of South Africa and Russia, and have also recently been reported from China and Brazil, and even more recently a diverse dinocephalian fauna has been described from Zimbabwe. This thesis reports a new primitive tapinocephalid dinocephalian, NHMB 1556, from the Upper Madumabisa Mudstone Formation in Zimbabwe. NHMB 1556 is considered to be closely related to Avenantia and it possesses primitive tapinocephalid characters, but is more derived than Tapinocaninus, the most primitive tapinocephalid dinocephalian known. NHMB 1556 is distinguished from other tapinocephalines by having a groove on the squamosal below its dorsal contact with the parietal, a low squamosal-parietal suture on the posterior border of the temporal fenestra, a vomer which extends posteroventrally and forms the anterior margin of the interpterygoidal vacuity and basisphenoid, which is semi-circular anteroventrally.
AC2017

South Africa is well known for its many, important fossil bearing deposits of Plio-Pleistocene age. Many of these sites contain abundant remains of extinct and extant animals including hominins. Non-herpetological fauna have been used to reconstruct important information about past environments and for chronological data. This study tried a different method; using herpefauna to establish past environments of Cooper’s Cave. Herpetological fauna potentially have numerous advantages in their use for such questions, including typically limited ranging behaviors, and specific temperature requirements. Despite these advantages only a few studies have even mentioned the presence of squamate fauna in the fossil assemblages of these sites. This study has demonstrated that herpefauna exists, in reasonable levels of abundance and with adequate preservation within the fossil record of the dolomitic region now known as the Cradle of Humankind. It has also demonstrated for the first time the presence of a relative abundance of herpefauna at numbers far greater than any previous study has recognized. The present study was however, handicapped in not being able to fully utilize the material at hand to interpret past environments, owing to the lack of comparative material needed to move beyond the family or generic level in most cases with any degree of confidence. However, Agamids and Pseudocordylids were described to generic level. However, the many shortcomings that this work highlighted should not be seen as reason not to pursue the study of herpefauna, but to improve present comparative collections and collecting methods around the fossils themselves.