The primary goal of numerical palaeobiology is to understand the processes that generate and eliminate extinct and extant biodiversity. It is important to examine key clades and adaptive assemblages, whose evolution appears intrinsically related to major events in deep time. Mesozoic marine reptiles represent an excellent candidate for investigation, having ascended to ecological dominance in the aftermath of the Permo-Triassic mass extinction and passed through multiple biotic crises. Observations from the rich Triassic marine reptile fossil record highlight diverse ecologies, providing tentative evidence for an exceptional radiation driven by new trophic opportunities - but quantitative tests for this are scarce. Others have highlighted the potential long-term impacts of extinction, and revealed that ichthyosaur evolution was reset following an extinction interval in the Late Triassic. Although a recent body of research has provided new insights into marine reptile macroevolution, many questions remain unanswered. In this thesis, I present several diverse case studies exploring the impacts of ecological opportunity and biotic perturbations in Mesozoic marine reptile macroevolution. Throughout, focus is placed on examining temporal and group-wide patterns of morphological and functional diversity (disparity) and testing rates of phenotypic evolution. Chapters 2-4 focus on Sauropterygia, the most diverse and ecologically disparate Mesozoic marine reptiles, while chapter 5 incorporates all Mesozoic marine reptiles as an inclusive adaptive assemblage. In brief, results show that the Triassic was a time of unusual diversification and high disparity in marine reptile evolution. Multiple lines of evidence show the Triassic was a time of marked morphological, functional and ecological proliferation. Results herein also reveal that sauropterygians, and marine reptiles as a whole, passed through a macroevolutionary bottleneck during the Late Triassic, similar to that identified for ichthyosaurs previously. Overall, this thesis supports the idea that major extinction events can have disproportionate effects on macroevolution, by catalysing exceptional radiations in their aftermath.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:685334 |
| Date | January 2015 |
| Creators | Stubbs, Thomas L. |
| Publisher | University of Bristol |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
Page generated in 0.0118 seconds