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- Morphology (2)
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- Gray fossil flora (1)
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- Ice Cores (1)
- Late Neogene (1)
- Leaf Cuticle (1)
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- Mio-Pliocene (1)
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- Tsuga (1)
- Vitis (1)
Articles 1 - 5 of 5
Full-Text Articles in Physical Sciences and Mathematics
Vitis Seeds (Vitaceae) From The Late Neogene Gray Fossil Site, Northeastern Tennessee, Usa., Fade Gong
Vitis Seeds (Vitaceae) From The Late Neogene Gray Fossil Site, Northeastern Tennessee, Usa., Fade Gong
Electronic Theses and Dissertations
This study focuses on the morphometric and systematic studies of fossil vitaceous seeds recently recovered from the Gray Fossil Site (7-4.5 Ma, latest Miocene-earliest Pliocene) northeastern Tennessee. Morphologically, all fossil seeds correspond to the extant subgenus Vitis (genus Vitis) of the Vitaceae based on the smooth dorsal surface with a centrally positioned chalaza connected with a conspicuous chalaza-apex groove and short linear ventral infolds that are slightly diverged apically. A multivariate analysis based on 11 measured characters from 76 complete seeds identified three types of seeds, each representing a distinct morphotaxon. Based on comparison with modern and fossil vitaceous …
A Phylogenetic Analysis Of Species Relationships In Hemlocks, The Genus Tsuga (Pinaceae)., Jordan David Baker
A Phylogenetic Analysis Of Species Relationships In Hemlocks, The Genus Tsuga (Pinaceae)., Jordan David Baker
Electronic Theses and Dissertations
The genus Tsuga is comprised of eight extant species found in North America and East Asia and four species represented by fossils from Europe and Japan. This study presents the first phylogenetic analysis based on structural, biochemical, and molecular sequence data. Characters obtained from published and unpublished literature were combined with new morphological characters from seeds, seedlings, and leaf cuticle material. Results from parsimony analyses of these characters differed from the published molecular based phylogeny. The non-molecular based phylogeny resolves two separate clades, a North American and an Asian, but did not group the western North American species, as in …
Salamanders Of The Mio-Pliocene Gray Fossil Site, Washington County, Tennessee., Grant Stanley Boardman
Salamanders Of The Mio-Pliocene Gray Fossil Site, Washington County, Tennessee., Grant Stanley Boardman
Electronic Theses and Dissertations
Screening efforts at the Gray Fossil Site, Washington County, Tennessee, have yielded a unique and diverse salamander fauna for the southern Appalachian Mio-Pliocene; including at least five taxa from three modern families (Ambystomatidae, Plethodontidae, and Salamandridae) supporting the woodland-pond interpretation of the site. All specimens represent the earliest record of their respective families in the Appalachian Mountains; with the Notophthalmus sp. vertebrae being the only Mio-Pliocene skeletal fossil known for the family Salamandridae in North America. Three types of plethodontid salamander are present, with one type representing the earliest known desmognathine. The desmognathine fossils lend credence to the 'Appalachian' origin …
Geodynamics Of Terrane Accretion Within Southern Alaska, Benjamin Patrick Hooks
Geodynamics Of Terrane Accretion Within Southern Alaska, Benjamin Patrick Hooks
Electronic Theses and Dissertations
The subduction and accretion of an exotic terrane at the southern margin of Alaska is driving uplift of the St. Elias and Alaska Ranges, and is responsible for some of the largest strain releases in history. Here are presented results from numerical models conditioned by geological observations that reproduce the tectonic landscape, deformation, and strain patterns at macro- (1000-km) and meso- (<100 >km) scales. These models utilize completely coupled thermal and mechanical solutions that account for the development of heterogeneities to both the thermal and rheological structure of the lithosphere. Perturbation to the thermal structure related to flattening of the …
Characterization Of Firn Microstructure Using Scanning Electron Microscopy: Implications For Physical Properties Measurements And Climate Reconstructions, Nicole Spaulding
Characterization Of Firn Microstructure Using Scanning Electron Microscopy: Implications For Physical Properties Measurements And Climate Reconstructions, Nicole Spaulding
Electronic Theses and Dissertations
Samples from 12 East Antarctic firn and ice cores were analyzed using scanning electron micrcoscopy (SEM) in order to first develop a technique for the accurate characterization of physical properties and then to investigate the relationship between the physical microstructure and chemical properties. Both physical properties, such as grain size and porosity, and chemical properties, such as major ion and trace element concentration, provide information about atmospheric temperature changes, impurity content, accumulation rate and deformation history; therefore the characterization of both types of properties is necessary. Further, knowledge of the relationship between the physical and chemical properties may increase our …