A partial articulated acanthodian from the Silurian of New Brunswick, Canada
Bibliographic record
Abstract
Vertebrates preserved in calcareous concretions collected from Silurian marginal-marine deposits near Nerepis, southern New Brunswick include agnathan thelodonts, a heterostracan, and possibly an anaspid, as well as spines and scales from an acanthodian (the only jawed fish remains). Several incomplete specimens of acanthodians, all determined as the same taxon Nerepisacanthus denisoni nov. gen. et sp., are described based on material identified in several museum collections. The fish-bearing nodules are from the Silurian Cunningham Creek Formation, which has been dated from ?late Llandovery (Telychian) – Ludlow (Ludlovian). The new species is only the second undisputed pre-Devonian acanthodian taxon known from articulated, although incomplete, specimens. N. denisoni has robust flank scales with a smooth crown bearing short subparallel ridges along the anterior edge, plus flatter scales with a crown formed of elongate, curved, areal-growth ridges, anterior to the pectoral region. The anterior dorsal fin spine is long, slightly curved and bears up to seven smooth longitudinal ridges of varying width on each side. The perichondrally ossified scapula is thin-walled and probably has a U-shaped cross section. “Dentition” cones and small denticles are preserved in the branchial or pharyngeal region. Although elements indisputably identifiable as dentigerous jaw bones were not found in the specimens, N. denisoni appears most closely related to the Early Devonian ischnacanthiform Acritolepis and is tentatively assigned to the family Acritolepidae Valiukevičius and Burrow.
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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 | 0.004 | 0.004 |
| Science and technology studies | 0.004 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.004 | 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".