We perform Ediacaran-style decay experiments on both sea anemones (Condylactis gigantea) and sea hares (Dolabella auricularia) in order to test between several proposed models of control on âdeath maskâ style preservation. Specifically, we test comparisons of rates of decay, patterns of decay, and better quantify the black âdecay haloâ precipitate noted in previous work. The results demonstrate a necessary threshold of dermal rigidity for âdeath maskâ style preservation, as well as potentially help test between diploblastic vs. triploblastic affinities for Ediacaran organisms. We find that while rate of decay was decelerated under Ediacaran-style conditions, pattern of character loss in both diploblastic and triploblastic organisms was conserved from the baseline experiments. Geochemical analyses of sediment from around the carcasses indicate that previous models of âdeath maskâ preservation might need to be assessed further as precipitation of FeS or clay mineral precursors may be decay-rate-dependent or affected by overall tissue lability of the carcass. Patterns of character loss associated with both the anemones and mollusks demonstrate a bias against preservation of the most labile tissues, such as anemone tentacles and internal gut system of the mollusks. Such biases have likely affected previous interpretations and controversies of the affinities of some iconic Ediacaran and Cambrian organisms. According to our results, absence of evidence for some of these features might be more closely linked with dermal lability rather than absence of feature all together.
| Identifer | oai:union.ndltd.org:VANDERBILT/oai:VANDERBILTETD:etd-07172017-161410 |
| Date | 27 July 2017 |
| Creators | Gibson, Brandt Michael |
| Contributors | Simon A.F. Darroch, Neil P. Kelley, Ralf Bennartz |
| Publisher | VANDERBILT |
| Source Sets | Vanderbilt University Theses |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.library.vanderbilt.edu/available/etd-07172017-161410/ |
| Rights | restrictone, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to Vanderbilt University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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