Re-assessment of the genus Helmolepis STENSIÖ 1932 (Actinopterygii: Platysiagidae) and the evolution of Platysiagids in the Early-Middle Triassic
Bibliographic record
Abstract
The type material of the rare, small actinopterygian Helmolepis gracilis Stensiö 1932 from the lower Griesbachian of East Greenland has been re-discovered in the Geologisk Museum of the University of Copenhagen. Two additional specimens, one presumably juvenile, have been identified in the same collection. More precise meristic features are reported and the reconstruction of the skull skeleton is considerably improved. Furthermore, another species, Helmolepis manis sp. nov. has been discovered in the Lower Triassic (Dienerian) of northwest Madagascar. The evidence of similar small-sized actinopterygian species in the Early Triassic suggests that platysiagids – recently also described from the Lower Smithian of western Canada – showed worldwide distribution at least by the Dienerian. Discovery of this new species further supports the assumption, that the Platysiagidae were not the offspring of derived Middle Triassic “perleidiform” actinopterygian fishes, but probably shared a common (unknown) ancestor older than the early Smithian, possibly of early Griesbachian age. The occurrence of closely related, small-sized actinopterygians in high latitudes by the early Dienerian and in the eastern Panthalassic Ocean by the early Smithian may be explained by an early or rapid dispersal event in combination with dwarfism in the recovery phase following the end-Permian mass extinction.
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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 | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".