New species of Silurian acanthodians from the Mackenzie Mountains, Canada
Bibliographic record
Abstract
Two new acanthodian taxa are described. The ischnacanthid Xylacanthus kenstewarti is based on large, dentigerous jaws, and Granulacanthus joenelsoni is based on isolated spines. The isolated remains of these species are similar in that they both possess pustulose denticles or tubercles, either on the mesial ridge (X. kenstewarti) or on the fin spines (G. joenelsoni). Jaws of X. kenstewarti are similar in size to those of Xylacanthus minutus, Ischnacanthus kingi, and I. wickhami and smaller than those of X. grandis. The jaws of X. kenstewarti are most similar to those of X. minutus, but are distinguished from this and other ischnacanthid species by a tapering patch of pustulose denticles that is widest midway along the jaw, mesial denticles that are simple blisterlike structures, the monocuspid, striated primary teeth that are subcircular in cross section, and a posterodorsal process that is enlarged. The spines of G. joenelsoni have distinctive tubercular ornamentation. Tubercles, or nodular ornaments on fin spines, are characteristic of primitive acanthodians, but the slender shape of the spines, the low number of spine ribs, and the fine striations posterior to the main ribs of each spine suggest that G. joenelsoni is a relatively advanced acanthodian. Xylacanthus kenstewarti and G. joenelsoni are from the Silurian (Wenlock or Ludlow) of the southern Mackenzie Mountains. Xylacanthus kenstewarti represents the earliest representative of the genus, the earliest unequivocal remains of a gnathostome from the Mackenzie Mountains, and extends the known geographical range of the genus from the Mackenzie Mountains east to Spitsbergen.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.003 | 0.002 |
| Science and technology studies | 0.003 | 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) | 0.003 | 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".