A Community-Scale Perspective on the Diversification of Tetrapod Ecology and Botanical Turnover based on the Pennsylvanian of the Maritimes Basin, Atlantic Canada

Modern terrestrial communities are complex and diverse, their assembly being influenced by a litany of abiotic and biotic drivers and constraints. Some of the most basic factors that govern their structure and function are thought to have been established in the Pennsylvanian (~323-299 Ma), as the ecological roles of terrestrial tetrapods rapidly diversified. At a global scale, the expansion of tetrapod ecology occurred roughly in concert with major disruption in plant community composition, leading some to propose a causal link between the two phenomena. My dissertation focuses on addressing whether plant community disruption and functional diversification of tetrapods occurred in concert at the community scale, using the Lower-Middle Pennsylvanian Maritimes Basin of Atlantic Canada as a case study. For this dissertation, I use body mass and diet as the variables through which I study tetrapod functional diversity. In the course of this investigation, I ask three foundational questions about community structure developments through the Lower-Middle Pennsylvanian of the Maritimes Basin: Did plant community assembly significantly change? Was there a significant shift in the body mass distributions of tetrapods? Was there any expansion in the dietary niches occupied by tetrapods? I show that two significant floral turnovers occurred during the studied interval, including one which likely involved a major disruption in community assembly rules, and that these are roughly concurrent with similar plant community disruption events from elsewhere in Euramerica. I expand upon a method of body mass estimation based on the dimensions of vertebral centra to show that body mass distributions did not change significantly through the studied interval. My body mass results also demonstrate that taphonomic biases may also explain the majority of differentiation between Pennsylvanian fossil body mass distributions and those of modern tropical estuarine environments. Lastly, I use a combination of both tooth morphology and biogeochemistry to make inferences of tetrapod diet, showing no conclusive evidence of expansion in tetrapod dietary ecology. Put together, the results of my dissertation reject the hypothesis that ecological diversification of tetrapods was a response to plant community disruption, and improve our understanding of the foundational processes driving terrestrial community structure.

Name thesis:degree_name

Doctor of Philosophy (Ph.D.)

Level thesis:degree_level

Doctoral

Discipline thesis:degree_discipline

Earth Sciences

Grantor dc:publisher

Carleton University

Year dc:date.issued

2025

Author dc:creator

• Whittingham, Misha

Statement dc:rights

• Copyright © 2025 the author(s). Theses may be used for non-commercial research, educational, or related academic purposes only. Such uses include personal study, distribution to students, research and scholarship. Theses may only be shared by linking to the Carleton University Institutional Repository and no part may be copied without proper attribution to the author; no part may be used for commercial purposes directly or indirectly via a for-profit platform; no adaptation or derivative works are permitted without consent from the copyright owner.

Language dc:language.iso

en

DOI

10.22215/etd/2025-16607

OAI identifier oai:identifier

oai:carleton.scholaris.ca:20.500.14718/43974