A multimethod analysis to assess locomotor capabilities in stem tetrapods from Blue Beach (Tournaisian; Early Carboniferous), Nova Scotia
Bibliographic record
Abstract
In vertebrate evolution the fin-to-limb transition was an important precursor to the diversification and radiation of terrestrial animals into novel environments. This transition began in the Devonian and continued through the Carboniferous and involved physiological and biomechanical changes. I used a multi-method approach to assess external and internal limb bone features to evaluate Early Carboniferous (Tournaisian) limb bones from Blue Beach and associated them with aquatic to terrestrial lifestyles. Tournaisian tetrapod material was collected at Blue Beach located near Hantsport, Nova Scotia, but much of it has not been formally described because the disarticulated and isolated tetrapod elements made identification to the species level difficult. In this thesis I described new morphotypes attributable to the family level which are used in the following chapters. Once the external morphology of the Blue Beach bones was described I compared them with the femora of extant aquatic, amphibious, and terrestrial tetrapods to evaluate which locomotor behaviour the fossil femora most resembled. I additionally examined cross-sectional bone profiles of Blue Beach tetrapod femora to infer lifestyle. Midshaft analyses relied on a single two-dimensional image to represent a dynamically structured bone so I also used a novel method for assessing three-dimensional trabecular data to qualitatively and quantitatively infer lifestyle from the Blue Beach femora. From the various analyses of internal and external bone morphology it was clear that external bone features of modern and early fossil tetrapod femora are dissimilar, which lead to difficulties in drawing conclusions based off external qualitative data. Internal data, from two-dimensional midshaft and three-dimensional trabecular structures, produced quantitative results that lead to the same conclusion, that the Blue Beach femora are consistent with those of aquatic animals. This implies that the initial diversification of the tetrapod body plans present in the Early Carboniferous was not the result of terrestrialization but appears to have preceded it.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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 teacher head, 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".