Dissertations / Theses on the topic 'Paleontology China'

The Sapeomithidae are a unique and poorly understood clade of Early Cretaceous birds from the Jehol Group of Liaoning Province, China. Four species of sapeomithids are known: Sapeornis chaoyangensis, Didactylornis jii, Sapeornis angus tis, and Shenshiornis primita. Omnivoropteryx sinousaorum is allied with sapeomithids, although its nomenclature remains a source of contention. The validity of these taxa is challenged via an in-depth anatomical revision and morphometric analyses involving 18 specimens of sapeomithids, including the aforementioned holotypes. The results reveal that the only anatomical difference separating each species is size, implying a growth series trend among the specimens. This provides clear evidence that these species are junior synonyms of Sapeornis chaoyangensis. In addition, critical anatomical descriptions previously unknown for these specimens expand our knowledge of this clade, paving the way for future anatomical and phylogenetic studies of this enigmatic avian taxon.

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

This thesis deals with the stratigraphy and brachiopod systematic palaeontology of the latest Devonian (Famennian) to Early Permian (Kungurian) sedimentary sequences of the Tarim Basin, NW China. Brachiopod faunas of latest Devonian and Carboniferous age have been published or currently in press in the course of the Ph.D candidature and are herein appendixed, while the Early Permian brachiopod faunas are systematically described in this thesis. The described Early Permian brachiopod faunas include 127 species, of which 29 are new and 12 indeterminate, and six new genera (subgenera) are proposed; Tarimella, Bmntonella, Marginifera (Arenaria), Marginifera (Nesiotia), Baliqliqia and Ustritskia. A new integrated brachiopod biostratigraphical zonation scheme is proposed, for the first time, for the latest Devonian-Early Permian sequences of the entire Tarim Basin on the basis of this study as well as previously published information (including the Candidate's own published papers). The scheme consists of twenty three brachiopod acm biozones, most of which replace previously proposed assemblage or assemblage zones. The age and distribution of these brachiopod zones within the Tarim Basin and their relationships with other important fossil groups are discussed. In terms of regional correlations and biostratigraphical affinities, the Late Devonian to Early Carboniferous brachiopod faunas of the Tarim Basin are closest to those from South China, while the Late Carboniferous faunas demonstrate strong similarities to coeval faunas from the Urals, central Asia, North China and South China. During the Asselian-Sakmarian, strong faunal links between the Tarim Basin and those of the Urals persisted, while at the same time links with central Asia, North China and South China weakened. On the other hand, during the Artinskian-Kungurian times, affinities of the Tarim faunas with the Urals/Russian Platform rapidly reduced, when those with peri-Gondwana (South Thailand, northern Tibet) and South China increased. Thirty lithofacies (or microfacies) types of four facies associations are recognised for the Late Devonian to early Permian sediments. Based on detailed lithostratigraphy, biostratigraphy and facies analysis, 23 third-order sequences belonging to four supcrsequences are identified for the Late Devonian to Early Permian successions, from which sea-level fluctuation curves are reconstructed. The sequence stratigraphical analysis reveals that four major regional regressions, each marking a distinct supersequence boundary, can be recognised; they correspond to the end-Serpukhovian, end-Moscovian, late Artinskian and end-Kungurian times, respectively. The development of these sequences is considered to have been formed and regulated by the interplay of both eustasy and tectonism. Using the system tract of a sequence as the mapping time unit, a succession of 47 palaeogeographical maps have been reconstructed through the Late Devonian to Early Permian. These maps reveal that the Tarim Basin was first immersed by southwest-directed (Recent geographical orientation) transgression in the late Famennian after the Caledonian Orogeny. Since then, the basin had maintained its geometry as a large, southwest-mouthed embayment until the late Moscovian when most areas were the uplifted above sea-level. The basin was flooded again in late Asselian-Artinskian times when a new transgression came from a large epicontinental sea lying to its northwest. Thereafter, marine deposition was restricted to local areas (southwestern and northwestern margins until the late Kungurian, while deposition of continental deposits prevailed and continued through the Middle and late Permian into the Triassic.

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.

Orientadora : Drª Renata Hanae Nagai
Dissertação (mestrado) - Universidade Federal do Paraná, Setor de Ciências da Terra, Programa de Pós-Graduação em Sistemas Costeiros e Oceânicos. Defesa: Pontal do Paraná, 23/05/2017
Inclui referências : f. 61-71
Resumo: A evolução dos padrões oceanográficos e climáticos do nosso planeta está diretamente ligada à alternância de ciclos glaciais e interglaciais que ocorreram durante o Quaternário associados à diversos atores da regulação climática. Os oceanos tropicais, como o Mar Sul da China (SCS), têm papel fundamental dentro desses processos, como uma importante região de comunicação entre altas e baixas latitudes. Analogamente, na atmosfera, o Sistema de Monção do Leste Asiático (EAM), permite esta comunicação. O EAM influencia significativamente os padrões oceanográficos sazonais do SCS, e suas interações estão intimamente ligados aos principais eventos climáticos registrados no Quaternário Superior. A presente dissertação investigou mudanças nas interações oceano-atmosfera entre o SCS e o EAM através de foraminíferos planctônicos de registros sedimentares marinhos, uma vez que este proxy permite inferir mudanças na estrutura da coluna d'água, no que diz respeito à produtividade primária e temperatura. A porcentagem de foraminíferos subsuperficiais/termoclina obtida em 11 registros sedimentares marinhos permitiu avaliar a variação espacial e temporal da camada de mistura (MLD) do SCS nos últimos 25 mil anos. Nesse período, variações da MLD estão relacionadas a variações na intensidade do EAM de inverno, em resposta a teleconecções atmosféricas de alta e baixas latitudes. A caracterização das assembleias de foraminíferos planctônicos do testemunho U1431D, retirado da região de mar profundo da porção leste do SCS durante o International Ocean Discovery Program (IODP) Expedition 349, foi aplicada no entendimento das condições ambientais (temperatura da superfície do mar e produtividade primária) no SCS nos últimos 300 mil anos. A evolução dos padrões hidrográficos do SCS apresenta forte relação com a mudanças na intensidade do EAM, especialmente nos eventos glaciais mais recentes. Nossos resultados apontam para a existência de gradientes latitudinais e longitudinais no SCS em resposta ao EAM e a entrada de águas do Pacífico, pela Corrente de Kuroshio. Palavras-chave: Interações oceano-atmosfera; Mar Sul da China; Sistema de Monção do Leste Asiático; Foraminíferos planctônicos; Quaternário Superior.
Abstract: Earth's oceanographic and climatic evolution is directly linked to Quaternary glacial and interglacial cycles driven by multiple climate regulation actors. Tropical oceans, as the South China Sea (SCS), play a key role in these processes as an important region of communication between high and low latitudes. Analogous, in the atmosphere, the East Asian Monsoon system (EAM) allows this communication. The EAM significantly influences the seasonal oceanographic patterns of the SCS, and the air-sea coupling between them are closely related to the major glacial/interglacial events recorded in the Late Quaternary. The present dissertation investigated changes in these air-sea interactions by examining planktonic foraminifera (PF) from marine sedimentary records, as this proxy allows the inference of water column conditions, particularly concerning primary productivity (PP) and upper thermal structure. The percentage of deep-dwellers PF obtained in 11 marine sedimentary records allowed to evaluate the spatial and temporal variation of the SCS mixed layer depth (MLD) in the last 25 thousand years. During this period, MLD variations are related to variations in EAM winter intensity in response to atmospheric teleconnections between high and low latitudes. The planktonic foraminifera assemblages from hole U1431D, taken from deep sea floor in the eastern SCS portion during the International Ocean Discovery Program (IODP) Expedition 349, was applied in understanding the SCS environmental conditions (sea surface temperature and primary productivity) in the last 300 thousand years. The SCS hydrographic patterns evolution is strongly related to EAM intensity changes, especially in recent cold events. Our results point to the existence of latitudinal and longitudinal gradients in SCS in response to EAM and the intrusion of Pacific waters by the Kuroshio Current. Key-words: Ocean-atmosphere interactions; South China Sea; East Asian Monsoon System; Planktonic Foraminifera; Late Quaternary.

Comme tous les organismes marins, les ostracodes subissent un changement drastique au cours de l'extinction en masse de la fin du Permien. En Chine du Sud, le Permien supérieur affleure largement. Des études précédentes ont été conduites sur la taxonomie, la biostratigraphie et le paléoenvironnement des ostracodes néritiques du Permien supérieur. C'est ici la première étude sur les ostracodes profonds du Permien supérieur de Chine et la première dans le monde sur le Permien terminal. A ce jour, les seules données disponibles sur les ostracodes profonds du Permien proviennent du Permien inférieur d'Indonésie et du Permien moyen - Wuchiapingien d'Italie. Dans cette thèse, quatre coupes de séries profondes de Chine du Sud (Bassin du Hunan-Guizhou-Guangxi et Bassin du Yangste inférieur) sont étudiées en détail pour la taxonomie, le paléoenvironnement (paléobathymétrie et niveau de paléo-oxygénation) et les processus "d'extinction". La taxonomie des ostracodes est le travail de base. Une faune diversifiée est représentée par 43 genres et 128 espèces. Deux nouvelles espèces Bairdia dongpanensis et Spinomicrocheilinella anterocompressa ont été décrites. Un nouveau genre Denticupachydomella n.gen. et deux nouvelles espèces Pseudobythocypris guiqianensis n.sp. et Denticupachydomella spinosa n.sp. sont proposés. Beaucoup de spécimens ont une conservation médiocre et ne présentent pas suffisamment de caractères pour une identification précise. Les spécimens déterminés appartiennent aux Palaeocopida, Podocopida et Myodocopida. Les espèces typiquement Paléozoïque dominent la faune et sont accompagnées de quelques formes à affinité mésozoïque (i.e. Abrobairdia, Lobobairdia). 19 espèces ont été rattachées à du matériel précédemment décrit du Dévonien supérieur au Permien supérieur d'Amérique du Nord, d'Europe et d'Asie du Sud-Est. La faune étudiée a un taux d'endémisme de 85.2%. La paléobathymétrie est analysée à partir du modèle de Lethiers & Raymond (1991) qui utilise les proportions d'ostracodes psychrosphériques/Bairdiidea/autres espèces néritiques. 38 espèces sont considérées comme psychrosphériques. Elles appartiennent aux Bairdiidae épineux, Bythocytheridae, Tricorninidae, Berounellinidae, Rectonariidae, Pachydomellidae, Healdiidae, Quasillitidae, Polycopidae, Discoidella et deux espèces indetminées de podocopid. La coupe de Dongpan est la plus profonde et présente des variations de bathymétrie depuis la plate-forme externe jusqu'au milieu bathyal. Ces interprétations sont bien en adéquation avec les résultats d'autres analyses (radiolaires, sédimentologie, minéralogie et géochimie). Quelques événements locaux (courants de turbidité) peuvent perturber le signal. Pour l'évaluation de la teneur en oxygène, le modèle FF% (pourcentage d'ostracodes filtreurs) de Lethiers & Whatley (1994) est appliqué pour la première fois à des faunes profondes. Un seul horizon dans la coupe de Dongpan présente un niveau d'oxygénation proche de la dysoxie. En milieu néritique, un intervalle de transition, avec des faunes typiquement paléozoïques et des nouveaux venus mésozoïques a récemment été mis en évidence. Il semble que ce phénomène soit observable également en milieu profond. Il ne semble pas y avoir de phénomène de miniaturisation chez les ostracodes profonds à l'approche de la limite Permien-Trias. Dans la coupe groupée Liuqiao-Dongpan, deux horizons d'extinction sont mis en évidence. Le premier horizon correspond à la crise majeure chez les radiolaires, à la régression, à une activité volcanique intense et peut-être un niveau disoxique. Ces niveau d'extinction sont corrélés avec le GSSP de la limite Permien-Trias à Meishan. Il semblerait que les événements d'extinction soient plus précoces en milieu profond qu'en milieu néritique.

A thesis submitted to the Faculty of Science, University of the Witwatersrand, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg, 2015.
The progress achieved on research of the different handaxe-bearing regions of China is making the study of the Acheulean an exciting and important field in the Chinese Palaeolithic. However, compared with other well-known Large Cutting Tool or LCT-bearing regions, e.g., Bose in southern China and Luonan in central China, the work in the Danjiangkou Reservoir Region (DRR) is still at the stage of data collection, and deeper research into the meaning of these materials is still under way. In international academic circles, the DRR is almost never considered in the latest discussions about the Chinese Acheulean. The work in this thesis attempts to improve this situation. The thesis is presented as four published papers and one submitted paper of Acheulean materials from the DRR, central China. Through a detailed study of these materials from typological, technological and morphological perspectives, I have now achieved significant understanding of the Acheulean techno-complex in DRR, especially in its regional variability and adaptation compared with other Acheulean regions in China. Lastly, the questions that are still awaiting resolution in the future are also discussed.