<i>Powichthys spitsbergensis</i> sp. nov., a new member of the Dipnomorpha (Sarcopterygii, lobe-finned fishes) from the Lower Devonian of Spitsbergen, with remarks on basal dipnomorph anatomy
Bibliographic record
Abstract
The Powichthyidae (Dipnomorpha, Sarcopterygii) were hitherto known from a single species, Powichthys thorsteinssoni, from the Lochkovian-Pragian of Arctic Canada. New material from the Early Devonian of Spitsbergen is referred here to a new species Powichthys spitsbergensis sp. nov., and provides additional data on the skull, dermal palate, palatoquadrate, post-orbital, and scales of the Powichthyidae. In particular, it reveals new morphological features, such as an internal process of the lacrimal, a strong anteroventral process of the scales, and the presence of large, upperoral dental plates, which cover the palate and suggest a crushing palatal bite, as in lungfishes. The structure of the skull agrees with Jessen's description of Powichthys thorsteinssoni, except that the junction between the supra-orbital and infra-orbital sensory-line canals is lacking in the Spitsbergen species. The exceptional preservation of the dermal elements of the palate shows that the presumed choana is in fact absent in the Powichthyidae, as in the Porolepiformes. The shape of the nasal capsule and the size and arrangement of the adjoining nerve canals are similar to those of the Porolepiformes, but contrary to Jessen’s assumption, the palatoquadrate seems to be significantly different.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 0.002 |
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".