The role of ecophysiology and paleoenvironmental dynamics in the Ediacaran biostratigraphic record
Abstract/Contents
- Abstract
- The Ediacaran Period (635 to 539 million years ago; Ma) represents one of the most dynamic periods in Earth History. Terminating the Neoproterozoic Era, the Ediacaran begins immediately after the second of two Snowball Earth global Glaciations, the Sturtian (717 to 560 Ma), and the Marinoan (640 to 635 Ma), which among other things had profound impacts on the global carbon cycle. Upon the final melting of the Marinoan Glaciation, a period of over 50 million years (Myr) passed in the early Ediacaran with no evidence of complex macroscopic eukaryotic or animal life. Bookending this interval is the continental-scale Gaskiers Glaciation (580-579 Ma) which shows up in deep-marine glaciogenic strata in Newfoundland and England today. Several hundred meters above these deposits are the earliest macroscopic eukaryotes and purported animals to appear in the fossil record, known as the Ediacara biota. These deep-water communities, identified as 'Avalon Assemblages' initially appear only in deep-marine slope and basinal environments for some 15 Myrs before radiating up into the continental shelves worldwide ca. 560 Ma. However, the basins in which they appear have no equivalent shallow-water facies, making it impossible to discern whether this pattern is a genuine evolutionary pattern, or the product of bias in the stratigraphic record. By cs. 555 Ma, the shallow-water 'White Sea Assemblage' became the most diverse interval in the Ediacaran, and records newly emerging 'Cambrian-style' fauna including mobile bilaterians and increasingly complex trace fossils. These groups continue into the terminal Ediacaran, known as the 'Nama Assemblage' ca. 550-539 Ma when all Ediacara biota go extinct at the Ediacaran-Cambrian boundary. The circumstances that surround the timing and drivers of this initial diversification however are unclear, and hypotheses have focused primarily on the role of environment, including global reorganization of marine redox conditions, changes in primary productivity, ecological escalation, and climate stability following the end of Snowball Earth glaciations. As a result, the interval remains actively studied by geologists and paleontologists, however, there remain critical unanswered questions regarding the timing and spatial evolution of the Ediacara biota.
Description
| Type of resource | text |
|---|---|
| Form | electronic resource; remote; computer; online resource |
| Extent | 1 online resource. |
| Place | California |
| Place | [Stanford, California] |
| Publisher | [Stanford University] |
| Copyright date | 2020; ©2020 |
| Publication date | 2020; 2020 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Author | Boag, Thomas Howard |
|---|---|
| Degree supervisor | Sperling, Erik |
| Thesis advisor | Sperling, Erik |
| Thesis advisor | Graham, S. A. (Stephan Alan), 1950- |
| Thesis advisor | Payne, Jonathan L |
| Thesis advisor | Somero, George N |
| Degree committee member | Graham, S. A. (Stephan Alan), 1950- |
| Degree committee member | Payne, Jonathan L |
| Degree committee member | Somero, George N |
| Associated with | Stanford University, Department of Geology |
Subjects
| Genre | Theses |
|---|---|
| Genre | Text |
Bibliographic information
| Statement of responsibility | Thomas Howard Boag. |
|---|---|
| Note | Submitted to the Department of Geology. |
| Thesis | Thesis Ph.D. Stanford University 2020. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2020 by Thomas Howard Boag
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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