Two partial actinopterygian neocrania (occipital ossifications) from Blue Beach, Nova Scotia
Bibliographic record
Abstract
The earliest Carboniferous period (Tournaisian stage) is a crucial interval in actinopterygian evolution, but the actinopterygian fossil record for this stage is dominated by flattened specimens referred to inconsistently defined summary taxa. The locality of Blue Beach in Nova Scotia preserves Tournaisian-aged strata of the Horton Bluff Formation and offers a critical window into the actinopterygian fauna. Significantly, actinopterygian specimens from this locality are often preserved in three dimensions, so even partially complete or fragmentary material provides valuable data on actinopterygian morphology and evolutionary dynamics. Here, we describe two partial actinopterygian neocrania from Blue Beach. We review actinopterygian neocranium morphology and the dorsal arterial system to provide a comparative basis identifying these new specimens. We find one neocranium (NSM 017.GF.017.007) is most like early-diverging actinopterygians from the Devonian period; the other (NSM 017.GF.017.004) is most similar to later-diverging Carboniferous actinopterygians. This result underscores the diversity of the actinopterygian fauna preserved in the Horton Bluff Formation and suggests that this fauna was mosaic in composition and non-continuous with derived European actinopterygian faunas. Furthermore, this result contributes to an emerging picture of a gradual transition between Devonian and Carboniferous actinopterygian faunas.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".