Histological insights into trait acquisition in non-mammalian synapsids
Thesis (Ph.D.)--University of Washington, 2019 The synapsid stem lineage is classically known to document a step-wise pattern of trait acquisition however, evidence of homoplasy in synapsids is common and increased scrutiny within synapsid clades and less readily apparent microanatomical characters...
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ftunivwashington:oai:digital.lib.washington.edu:1773/45114 2023-05-15T13:37:32+02:00 Histological insights into trait acquisition in non-mammalian synapsids Whitney, Megan Sidor, Christian A 2019 application/pdf http://hdl.handle.net/1773/45114 en_US eng Appendix 3.xlsx; spreadsheet; Chapter 4 Empty Sockets and Replacement p-vals. values alone.xlsx; spreadsheet; Chapter 3 Raw Data. Appendix 1.xlsx; spreadsheet; Chapter 4 Raw Data. Appendix 4.xlsx; spreadsheet; Chapter 4 Dentition Scores. Whitney_washington_0250E_20995.pdf http://hdl.handle.net/1773/45114 CC BY-NC-ND dentition paleohistology periodontal ligament physiology synapsid Paleontology Biology Thesis 2019 ftunivwashington 2023-03-12T18:59:54Z Thesis (Ph.D.)--University of Washington, 2019 The synapsid stem lineage is classically known to document a step-wise pattern of trait acquisition however, evidence of homoplasy in synapsids is common and increased scrutiny within synapsid clades and less readily apparent microanatomical characters may not follow classic step-wise patterns. This dissertation examines a broad taxonomic sampling of synapsid fossils with special attention to the histological details of their dentitions to test for patterns of trait acquisition. In the first chapter, we describe the peculiar dentition of tapinocephalids, an early herbivorous group of synapsids. Tapinocephalids were the first synapsids to acquire mammal-like specializations such as precise tooth-to-tooth occlusion and a periodontal ligament while retaining ancestral features like alternating and rapid tooth replacement and wavy prismless enamel. The combination of traits that make up the tapinocephalid dentition are not represented in modern amniotes and appear to have been specialized to herbivory. In the second chapter, I compare seasonal physiological patterns captured by the growth marks in the dentine of Lystrosaurus from South Africa and Antarctica. While South African Lystrosaurus dentine shows evidence of severe and punctuated physiological stress, Antarctic specimens reveal a more constant, but less extreme amount of stress. This may reflect different responses to seasonality where Lystrosaurus living in South Africa experienced intense periods of drought while those in Antarctica experienced prolonged periods of darkness due to its high latitudinal position. These differences, although significant, are relatively minor suggesting a level of flexibility in Lystrosaurus physiology that would be expected from endothermic metabolisms. In the third chapter, we test for taphonomic proxies for tooth attachment in the proportion of empty tooth sockets in fossil synapsid jaws. We surveyed non-occluding jaws of most major clades and families of synapsids for the ... Thesis Antarc* Antarctic Antarctica University of Washington, Seattle: ResearchWorks Antarctic |
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Open Polar |
collection |
University of Washington, Seattle: ResearchWorks |
op_collection_id |
ftunivwashington |
language |
English |
topic |
dentition paleohistology periodontal ligament physiology synapsid Paleontology Biology |
spellingShingle |
dentition paleohistology periodontal ligament physiology synapsid Paleontology Biology Whitney, Megan Histological insights into trait acquisition in non-mammalian synapsids |
topic_facet |
dentition paleohistology periodontal ligament physiology synapsid Paleontology Biology |
description |
Thesis (Ph.D.)--University of Washington, 2019 The synapsid stem lineage is classically known to document a step-wise pattern of trait acquisition however, evidence of homoplasy in synapsids is common and increased scrutiny within synapsid clades and less readily apparent microanatomical characters may not follow classic step-wise patterns. This dissertation examines a broad taxonomic sampling of synapsid fossils with special attention to the histological details of their dentitions to test for patterns of trait acquisition. In the first chapter, we describe the peculiar dentition of tapinocephalids, an early herbivorous group of synapsids. Tapinocephalids were the first synapsids to acquire mammal-like specializations such as precise tooth-to-tooth occlusion and a periodontal ligament while retaining ancestral features like alternating and rapid tooth replacement and wavy prismless enamel. The combination of traits that make up the tapinocephalid dentition are not represented in modern amniotes and appear to have been specialized to herbivory. In the second chapter, I compare seasonal physiological patterns captured by the growth marks in the dentine of Lystrosaurus from South Africa and Antarctica. While South African Lystrosaurus dentine shows evidence of severe and punctuated physiological stress, Antarctic specimens reveal a more constant, but less extreme amount of stress. This may reflect different responses to seasonality where Lystrosaurus living in South Africa experienced intense periods of drought while those in Antarctica experienced prolonged periods of darkness due to its high latitudinal position. These differences, although significant, are relatively minor suggesting a level of flexibility in Lystrosaurus physiology that would be expected from endothermic metabolisms. In the third chapter, we test for taphonomic proxies for tooth attachment in the proportion of empty tooth sockets in fossil synapsid jaws. We surveyed non-occluding jaws of most major clades and families of synapsids for the ... |
author2 |
Sidor, Christian A |
format |
Thesis |
author |
Whitney, Megan |
author_facet |
Whitney, Megan |
author_sort |
Whitney, Megan |
title |
Histological insights into trait acquisition in non-mammalian synapsids |
title_short |
Histological insights into trait acquisition in non-mammalian synapsids |
title_full |
Histological insights into trait acquisition in non-mammalian synapsids |
title_fullStr |
Histological insights into trait acquisition in non-mammalian synapsids |
title_full_unstemmed |
Histological insights into trait acquisition in non-mammalian synapsids |
title_sort |
histological insights into trait acquisition in non-mammalian synapsids |
publishDate |
2019 |
url |
http://hdl.handle.net/1773/45114 |
geographic |
Antarctic |
geographic_facet |
Antarctic |
genre |
Antarc* Antarctic Antarctica |
genre_facet |
Antarc* Antarctic Antarctica |
op_relation |
Appendix 3.xlsx; spreadsheet; Chapter 4 Empty Sockets and Replacement p-vals. values alone.xlsx; spreadsheet; Chapter 3 Raw Data. Appendix 1.xlsx; spreadsheet; Chapter 4 Raw Data. Appendix 4.xlsx; spreadsheet; Chapter 4 Dentition Scores. Whitney_washington_0250E_20995.pdf http://hdl.handle.net/1773/45114 |
op_rights |
CC BY-NC-ND |
_version_ |
1766093797612060672 |