A Community-Scale Perspective on the Diversification of Tetrapod Ecology and Botanical Turnover based on the Pennsylvanian of the Maritimes Basin, Atlantic Canada
Bibliographic record
Abstract
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.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.003 |
| Science and technology studies | 0.003 | 0.003 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".