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  • 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.
21

Experimental assessment of early diagenetic changes in marine bivalve shells

Huang, Zhenzhen, 1982- January 2006 (has links)
To study the influence of early diagenesis, left valves of fresh cultured bivalves (Mytilus edulis) were deployed in the natural environments (Panama, Barbados and New Brunswick), and right valves were kept in the laboratory as the controls. After 9 days, 8 months and 1 year, the retrieved shells have shown different macroscopic changes in weight, shell area, colour and luster. The microstructure of nacre shows organic matrix maceration, dissolution on the edges of tablets, and abiotic CaC03 reprecipitation on the surface and edges of nacre tablets. High-precision analyses of their carbon and oxygen stable isotope ratios show bulk differences of up to 0.4%o between experimental and control valves within 1 year. Results therefore indicate that early diagenesis can start very quickly post-mortem, and the nature of these changes varies with burial environments.
22

Utility of fossil cuticle morphology applied to the taphonomy and taxonomy of decapod crustaceans

Waugh, David A. 13 June 2014 (has links)
<p> The purpose of the dissertation is to examine the microstructural variations within cuticle of brachyuran decapod crustaceans, the crabs and other selected decapods, in order to identify innovative character states in extant organisms and in whole or fragmentary fossil material that can be observed, coded, and treated in phylogenetic analyses. This is an entirely new approach to the study of decapod phylogeny that will link fossil and extant decapod datasets in a manner that previously has been impossible.</p>
23

The fossil record as an archive of biological information in marine ice-scoured environments : Canadian Arctic Ocean

Bibeau, Karine. January 2006 (has links)
Post-mortem alteration of bivalve shells on arctic ice-scoured shelves helps illucidate the fidelity of death and fossil assemblages in these settings. Degradation rates and processes were constrained by (1) characterizing the taphonomic signature of death assemblages, (2) evaluating the live-dead fidelity of the benthos, and (3) net changes in experimentally deployed shells. Results revealed an extremely harsh taphonomic mill controlled by bioerosion, fragmentation and dissolution. Only select species accumulated in death assemblages, resulting in low taxonomic fidelity; at the habitat level 50% of the live species are found dead. 100% of the dead species are found alive, suggesting no temporal or spatial exotic contributions. / Selectively preserved species could be time-averaged over 1 000s of years based on a preliminary model, yet high damage profiles suggest shorter scales of time-averaging. Skeletons are highly degraded compared to assemblages from temperate or tropical seas and reflect only a portion the living skeletonized community.
24

Fauna and stratigraphy of the Kimmswick limetone of Missouri and Illinois ... /

Bradley, John Hodgdon, January 1924 (has links)
Thesis (Ph. D.)--University of Chicago, Department of Geology. / A Dissertation, submitted to the Faculty of the Ogden Graduate School of Science, in candidacy for the Degree of Doctor of Philosophy, Department of Geology. Includes bibliographical references.
25

The Richmond fauna of northeastern Illinois ... /

Evans, John Robert Charles. January 1924 (has links)
Thesis (Ph. D.)--University of Chicago, Department of Geology. / Includes bibliographical references.
26

Systematics and phylogenetics of the family Streptacididae (Gastropoda: Heterobranchia) from Devonian through Triassic marine strata

Campbell, Matthew R. January 2004 (has links)
Thesis (Ph.D.)--Indiana University, Dept. of Geological Sciences, 2004. / Title from PDF t.p. (viewed Dec. 1, 2008). Source: Dissertation Abstracts International, Volume: 66-01, Section: B, page: 0172. Co-Chairs: N. Gary Lane; Lisa M. Pratt.
27

Notes on certain Ordovician faunas of the Inyo Mountains, California

Phleger, Fred B., January 1932 (has links)
Thesis (Masters) -- California Institute of Technology, 1932. / Title from home page (viewed 05/10/2010). Includes bibliographic references.
28

Over de samenstellung en het ontstaan van krijt- en mergel-gesteenten van de Molukkan

Tan Sin Hok. January 1927 (has links)
Proefschrift (Ph. D.)--Technischen Hoogeschool te Delft, 1927. / Bibliography: p. [152]-165.
29

The brittle star fauna of the Hunsrück Slate and a phylogeny of the Paleozoic Ophiuroidea /

Glass, Alexander. January 2006 (has links)
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2006. / Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6270. Adviser: Daniel B. Blake. Includes bibliographical references (leaves 571-610) Available on microfilm from Pro Quest Information and Learning.
30

Taxonomy, biostratigraphy and paleoecology of lower Silurian conodonts from the Anse a Pierre-Loiselle Formation, Gaspe Peninsula, Quebec.

Hitch, Michael William. January 1990 (has links)
Conodonts of late Llandovery age have been collected from the Anse a Pierre-Loiselle Formation, the deposition of which represents a deepening episode in the generally shallow deposition of the Chaleur Group in southern Gaspe. The fauna is dominated numerically by elements assigned to Panderodus, Oulodus?, and Ozarkodina with elements of Aulacognathus, Carniodus, Distomodus, Johnognathus, Kockelella, Pterospathodus, and Walliserodus as well as rate or indeterminate taxa. One genus is new, represented by one species: Digitodontus bellistriatus. Other new species include: Apsidognathus sulcatus, Pseudooneotodus pyramis and Pterospathodus? ceragnathoides. Based on these faunas the unit is considered to represent deposition of Llandovery C$\sb6$--early Wenlock age. Due to the low abundance of zonal indicator species Pterospathodus celloni and P. amorphognathoides, a new taxon range zone is established to encompass the total range of the new species P.? ceragnathoides which is locally abundant. The position of the Llandovery-Wenlock boundary remains unclear. (Abstract shortened by UMI.)

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