• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 47
  • 20
  • 19
  • 10
  • 4
  • 2
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 159
  • 30
  • 25
  • 24
  • 19
  • 17
  • 16
  • 15
  • 14
  • 14
  • 13
  • 12
  • 11
  • 11
  • 11
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

New Records of Colubrids from the late Hemphillian Gray Fossil Site of Northeastern Tennessee

Jurestovsky, Derek J 01 May 2016 (has links)
The Gray Fossil Site is a rich Hemphillian (North American Land Mammal Age) locality located in northeastern Tennessee which has produced tens-of-thousands of fossils of multiple taxa including hundreds of individual snake skeletal remains. Analyzed here are cranial and vertebral fossils identified as belonging to various colubrid taxa including Carphophis sp., Gyalopion sp., Heterodon sp., Natricinae indeterminate, Thamnophis sp., and a new, undescribed genus and species. In addition, multiple new features of snake vertebrae are described, some of which question the validity of the genus Neonatrix. Finally, the distribution and paleoecology of the listed genera allows an interpretation of how snake biogeography have transformed in the southern Appalachians since the Hemphillian.
32

Peccaries (Artiodactyla: Tayassuidae) from the Late Miocene to Early Pliocene Gray Fossil Site: Regional Implications with a Review of Tayassuinae

Doughty, Evan M 01 May 2016 (has links)
Analysis of the Gray Fossil Site peccary material indicates the presence of up to three species. Comparisons with the tayassuid material known from the Tyner Farm and Bone Valley Formation of Florida allows the identification of Mylohyus elmorei and at the GFS. Within the GFS material, Prosthennops cf. P. serus and cf. Catagonus sp. are also tentatively recognized but further verification is required. The known range for Prosthennops is expanded into the Appalachian region. Presence of M. elmorei at the Gray Fossil Site provides the first known occurrence of this species outside of the Palmetto fauna of Florida, indicating that the species once exhibited a larger range within the southeastern United States than previously known. Overall, the presence of M. elmorei.indicates another parallel to the Palmetto Fauna of the Bone Valley Formation whereas Prosthennops cf. P. serus may indicate a connection to the Hemphillian of the western United States.
33

Gray Fossil Site: 10 Years of Research

Schubert, Blaine W., Mead, Jim I. 01 January 2011 (has links)
https://dc.etsu.edu/etsu_books/1097/thumbnail.jpg
34

Oligo-Miocene pseudocheirid diversity and the early evolution of ringtail possums (Marsupialia)

Roberts, Karen K, Biological, Earth & Environmental Sciences, Faculty of Science, UNSW January 2008 (has links)
The marsupial family Pseudocheiridae is currently known from seventeen species of six genera in Australia and New Guinea. These small to medium-sized arboreal animals are nocturnal and folivorous. Extinct pseudocheirids are recognised from several mid to late Cenozoic fossil localities across Australia and New Guinea. The single largest collection of pseudocheirid fossils has been recovered from the Oligo-Miocene freshwater carbonates of the Riversleigh World Heritage Area in northwest Queensland. This collection, which includes the first pseudocheirid cranial fossils, forms the basis of this investigation. Three new extinct pseudocheirid genera together containing four species are identified and described. Six new species of Paljara, Marlu and Pildra are also described from Riversleigh. Two of the new Marlu species are reported from South Australia??s Leaf Locality. From Riversleigh, Marlu kutjamarpensis is identified and additional material of Paljara tirarensae and P. nancyhawardae documented. New species attributed to Marlu and Pildra necessitate revision of those genera. Cranial material is identified for three of the new species. The rostrum of archaic pseudocheirids is shorter than in extant forms but cranial morphology is similar overall. Phylogenetic relationships of all extinct pseudocheirids are analysed. They include all new and previously described species, most of which have never been examined in a parsimony-based analysis. Two hypotheses of pseudocheirid evolution are presented: a paired lineage hypothesis and a single lineage hypothesis. Both hypotheses demonstrate that species of Paljara are not the most plesiomorphic pseudocheirids, Marlu praecursor does not cluster with other species of Marlu, the new genus Gawinga is most closely related to Paljara and there are no representatives of the extant genus Pseudochirops in any pre-Pliocene locality. All extant pseudocheirids cluster to form a crown clade sister to a stem lineage of Pseudokoala and Marlu species. Pseudocheirids are found in all Oligo-Miocene faunal zones of Riversleigh. Species of Paljara and Marlu are most frequently recovered from Faunal Zone B and C deposits respectively. Four pseudocheirid species biostratigraphically correlate the Kutjamarpu local fauna of the Leaf Locality with Faunal Zones B and C of Riversleigh, suggesting an early to middle Miocene age for both deposits. Modern pseudocheirids first evolved no later than the late Miocene from a descendant of the Marlu + Pseudokoala lineage when all other Oligo-Miocene pseudocheirids became extinct. At least three pseudocheirid lineages dispersed to New Guinea approximately five million years ago, but ecological barriers probably prevented subsequent migrations between the two landmasses.
35

Characterization of Miocene-Pliocene carbonate platforms, southern Southwest Palawan Basin, Philippines

Sta. Ana, Ma. Corazon Victor 02 June 2009 (has links)
Isolated carbonate platforms and buildups of the Likas Formation provide a long record of carbonate sedimentation in the southern end of the Southwest Palawan Basin. While most carbonate platforms terminated in early Miocene and middle Miocene time in northern parts of western offshore Palawan (i.e. Northwest Palawan Basin and central South Palawan), carbonate deposition began later in the south during late middle Miocene time. Carbonate platforms of the Likas Formation developed in the Paragua sub-basin, which is interpreted to be a depozone eastward of the Palawan accretionary wedge in the structurally complex Southwest Palawan Basin. A regional 2D seismic grid and borehole data from four wells were used to analyze the growth patterns of the carbonate platforms, identify seismic facies, and reconstruct the evolution of the platforms. The carbonate platforms developed on the folded and faulted middle to premiddle Miocene siliciclastic strata. These older siliciclastic units were thrusted onto the southern end of the North Palawan microcontinental fragment, which represents a block of continental crust that drifted southward from South China during early Tertiary time. The platforms aggraded over time and backstepped to keep pace with increasing rates of relative sea level rise. Karst features are recognizable on seismic sections and indicate that the platforms were subaerially exposed at various times during their development. The platforms exhibit variable morphology from faulting and tilting. The platforms terminated in early Pliocene time, as relative sea level continued to rise, and were buried by deep-marine siliciclastic units.
36

METALLOGENETIC CONTROLS ON MIOCENE HIGH-SULPHIDATION EPITHERMAL GOLD MINERALIZATION, ALTO CHICAMA DISTRICT, LA LIBERTAD, NORTHERN PERÚ

Montgomery, Allan Trevor 05 April 2012 (has links)
The Alto Chicama district, Central Andean Cordillera Occidental, La Libertad, northern Perú, hosts the 14 M oz, Miocene Lagunas Norte high-sulphidation epithermal Au-(Ag) deposit (Latitude 7° 56ʹ30ʺ S; Longitude 78°14ʹ50ʺ W), in addition to several important, epithermal and mesothermal precious ± base-metal vein systems and porphyry Cu-Au-(Mo) deposits and prospects. The district is underlain by lower Oligocene-to-Middle Miocene, subaerial, Calipuy Supergroup volcanic rocks, unconformably overlying Upper Jurassic – Lower Cretaceous marine sedimentary strata affected by late Eocene-early Oligocene thin-skinned fold and thrust deformation. Mineralization at Lagunas Norte is largely hosted by intensely-folded Valanginian Chimú Formation quartz arenite, but extends into overlying, weakly-deformed, Lower Miocene dacitic volcaniclastic deposits. Fold- and thrust-related deformation at the deposit, and subsequent magmatic and hydrothermal activity, were localized along a long-lived, crustal-scale cross-strike discontinuity. Hydrothermal activity at Lagunas Norte was associated with local extension within an overall regional compressive regime. Ore formation occurred during the terminal stages of andesitic-to-dacitic magmatism in the deposit area, immediately following the sector collapse of an adjacent volcanic centre, and during eruption of late-stage peripheral dacitic domes. Intense advanced-argillic alteration occurred in at least two major pulses over a ~ 0.9 m.y. period, implying repeated magma influx in a shallow subjacent chamber. The ensuing Au-(Ag)-pyrite-enargite deposition resulted from mixing of magmatic vapour with oxidized groundwaters, a process stimulated by the contiguous incision of a steep-walled valley-pediment. The local volcanic rocks record a transition from “normal arc” to higher-pressure “adakitic” magmatism, initiated during ore deposition at Lagunas Norte, but exhibited by the entire Calipuy arc in northern Perú, and interpreted to reflect the destabilization of plagioclase and stabilization of garnet in inferred lower-crustal magmas. The progressive depletion of 18O and D in meteoric water recorded in late Oligocene-to-Late Miocene hypogene and supergene minerals is in permissive agreement with major uplift from ~ 1000 m to over 3000 m a.s.l. during hydrothermal activity. Hydrothermal activity and related ore deposition at Lagunas Norte unambiguously predated, by at least 2 m.y., the impingement of the aseismic Nazca Ridge at the Perú Trench and the ensuing flattening of the subducting slab / Thesis (Ph.D, Geological Sciences & Geological Engineering) -- Queen's University, 2012-04-05 11:09:14.751
37

Fossil angiosperms as indicators of early Tertiary conditions in Africa with special reference to the Miocene flora of Rusinga Island, Lake Victoria

Chesters, Kathleen Isabel Margaret January 1958 (has links)
No description available.
38

Oligo-Miocene pseudocheirid diversity and the early evolution of ringtail possums (Marsupialia)

Roberts, Karen K, Biological, Earth & Environmental Sciences, Faculty of Science, UNSW January 2008 (has links)
The marsupial family Pseudocheiridae is currently known from seventeen species of six genera in Australia and New Guinea. These small to medium-sized arboreal animals are nocturnal and folivorous. Extinct pseudocheirids are recognised from several mid to late Cenozoic fossil localities across Australia and New Guinea. The single largest collection of pseudocheirid fossils has been recovered from the Oligo-Miocene freshwater carbonates of the Riversleigh World Heritage Area in northwest Queensland. This collection, which includes the first pseudocheirid cranial fossils, forms the basis of this investigation. Three new extinct pseudocheirid genera together containing four species are identified and described. Six new species of Paljara, Marlu and Pildra are also described from Riversleigh. Two of the new Marlu species are reported from South Australia??s Leaf Locality. From Riversleigh, Marlu kutjamarpensis is identified and additional material of Paljara tirarensae and P. nancyhawardae documented. New species attributed to Marlu and Pildra necessitate revision of those genera. Cranial material is identified for three of the new species. The rostrum of archaic pseudocheirids is shorter than in extant forms but cranial morphology is similar overall. Phylogenetic relationships of all extinct pseudocheirids are analysed. They include all new and previously described species, most of which have never been examined in a parsimony-based analysis. Two hypotheses of pseudocheirid evolution are presented: a paired lineage hypothesis and a single lineage hypothesis. Both hypotheses demonstrate that species of Paljara are not the most plesiomorphic pseudocheirids, Marlu praecursor does not cluster with other species of Marlu, the new genus Gawinga is most closely related to Paljara and there are no representatives of the extant genus Pseudochirops in any pre-Pliocene locality. All extant pseudocheirids cluster to form a crown clade sister to a stem lineage of Pseudokoala and Marlu species. Pseudocheirids are found in all Oligo-Miocene faunal zones of Riversleigh. Species of Paljara and Marlu are most frequently recovered from Faunal Zone B and C deposits respectively. Four pseudocheirid species biostratigraphically correlate the Kutjamarpu local fauna of the Leaf Locality with Faunal Zones B and C of Riversleigh, suggesting an early to middle Miocene age for both deposits. Modern pseudocheirids first evolved no later than the late Miocene from a descendant of the Marlu + Pseudokoala lineage when all other Oligo-Miocene pseudocheirids became extinct. At least three pseudocheirid lineages dispersed to New Guinea approximately five million years ago, but ecological barriers probably prevented subsequent migrations between the two landmasses.
39

Bilateral Asymmetry in Incisors: Implications for Miocene Hominoid Species Diagnosis

Davis, Candace Ann 01 August 2011 (has links)
AN ABSTRACT OF THE DISSERTATION OF CANDACE A. DAVIS, for the Doctor of Philosophy Degree in ANTHROPOLOGY, presented on March 31, 2011, at Southern Illinois University at Carbondale. TITLE: BILATERAL ASYMMETRY IN INCISORS: IMPLICATIONS FOR MIOCENE HOMINOID SPECIES DIAGNOSIS MAJOR PROFESSOR: Dr. Robert S. Corruccini The primary purpose of this dissertation is to show how knowledge of variation and asymmetry in incisor antimeric pairs of living great ape genera can be utilized as a "yardstick" for pairwise comparisons of isolated Miocene ape incisors from the two genera Kenyapithecus and Equatorius . The research was designed to help determine whether these fossil teeth could be reliably sorted into one or more than one genera. Both metric and morphological data for each class of incisor were recorded for Kenyapithecus and Equatorius , and resampling was performed to determine the significance of variation (p<.05) for each of 12 traits. Intraindividual antimeric differences in three genera of extant great apes were compared with interspecimen differences between Equatorius and Kenyapithecus. Pairwise comparisons using resampling sorted out which traits showed intraindividual significant variation and which could be used to discriminate between the two fossil genera under consideration. Based on these results, one can cautiously conclude the two fossil species within these genera are not different enough to justify placing them in two different genera.
40

Descrição morfológica e posicionamento filogenético de um lagarto (Reptilia, Squamata) do Mioceno Inferior da Formação Chichínales, General Roca, Província de Río Negro, Argentina / Morphological description and phylogeny of a lizard (Reptilia, Squamata) from the Lower Miocene, Chichínales Formation, General Roca, Río Negro Province, Argentina

Ana Bottallo de Aguiar Quadros 29 January 2016 (has links)
Embora os escamados sejam comumente encontrados em sítios fossilíferos cenozóicos sul&minus;americanos, materiais esqueléticos completos são raros. Apenas alguns poucos exemplares assim foram registrados, com a maioria dos achados representando materiais fragmentários de crânio e mandíbulas ou vértebras isoladas. Dentre as localidades provedoras de vertebrados fósseis na América do Sul, a Formação Chichínales se destaca pela recente descoberta, em seus sedimentos, de um crânio quase completo de um lagarto teiídeo previamente desconhecido. Dada a fauna associada, a idade da formação é definida como Mioceno Temprano (Colhuehuapense). No presente estudo, conclui&minus;se, através de uma análise filogenética contendo 39 espécies viventes e fósseis de escamados e 149 caracteres osteológicos, que este material pertence a uma nova espécie do gênero contemporâneo Callopistes. Uma descrição morfológica detalhada do fóssil, obtida através de análises estereoscópicas e de microtomografia computadorizada de alta resolução (CT Scan), também é apresentada. A matriz morfológica foi analisada com o auxílio do software TNT Versão 1.1, seguindo o princípio de máxima parcimônia, com todos os caracteres tratados com a mesma pesagem, resultando em quatro árvores igualmente parcimoniosas, que foram então utilizadas para a construção de uma árvore de consenso estrito. Em todas as quatro árvores, o novo táxon posicionou&minus;se dentro da família Teiidae como um membro do clado formado pelas demais espécies viventes de Callopistes. Entretanto, não foi possível estabelecer uma relação de grupo&minus;irmão inequívoca entre as duas espécies de Callopistes presentes na análise e o fóssil. A atual distribuição das duas espécies viventes de Callopistes e a localidade de onde foi recuperado o fóssil em estudo indicam que esse gênero possuía uma distribuição muito mais ampla no passado, chegando a áreas patagônicas cis&minus;Andinas, diferentemente das áreas trans&minus;Andinas de altitude onde as duas espécies atuais estão restritas / Although squamates are commonly found in most Caenozoic south american fossil beds, complete skeletal materials are rare. Only a few examples exist, with most findings representing fragmentary cranial or jaw materials or isolated vertebrae. Among the known South American vertebrate fossil localities, the Chichínales formation rendered recently a mostly complete skull of a previously unknown teiid lizard. Given the associated fauna, the age of the formation is defined as Early Miocene (Colhuehuapense). Here, I show that this fossil represents a new species of the extant genus Callopistes through a phylogenetic analysis of extant and extinct squamates that includes 39 taxa and 149 osteological characters. I also provide a detailed description of the new fossil teiid based on both stereoscopical and high-resolution X&minus;ray computed tomography (CT Scan) analyses. The data matrix was analyzed performing a equally weighted parsimony analysis using the software TNT Version 1.1 that resulted in four equally most parsimonius trees, which were then used to built a strict consensus tree. In all four trees, the fossil lizard was recovered within the Callopistes lineage, nested inside the family Teiidae. Nevertheless, I was unable to establish which of the two Callopistes species present in the analysis were more closely related to the fossil. The present distribution of the two extant species of Callopistes and the locality from where the fossil was recovered indicate that this genus had a much broader distribution in the past, reaching cis&minus;Andean areas of Patagonia, apart from the trans&minus;Andean areas where the two extant species are restricted

Page generated in 0.0321 seconds