Structure of the calcitic layer of the aptychus of the ammonite genus Peltoceras
Bibliographic record
Abstract
The aptychi of ammonites combined the functions of lower jaws and protective opercula. They consist of two parts: an inner organic layer and an outer calcitic lamella. In different evolutionary lineages of ammonites, the shape of aptychi, the sculpture of their surface and the microstructure of the calcitic layer vary greatly. However, the structure of the aptychi is not known for all evolutionary lineages of ammonites. Although numerous aptychi have been described for the Jurassic family Aspidoceratidae, almost all of them belong to only one evolutionary branch of this family – the Aspidoceratinae ( sensu lato ). For the second branch – the Peltoceratinae, only one aptychus had been described to date and the structure of its calcitic layer remained unknown. In this article, for the first time, the structure of the aptychus of the Peltoceratinae (upper Callovian Peltoceras ) is described. The surface of this aptychus is covered with rough ribs and the calcitic part consists of only one layer of dense calcite. The thickness of the aptychus is much greater than that of the aptychi of supposed ancestors of the Peltoceratinae. The increase in the thickness of the aptychi in both the Aspidoceratinae and the Peltoceratinae, contemporaneously with the appearance of spines on their shells, is most likely related to increasing the protective function of the aptychi of these ammonites in the late Callovian.
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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 | 0.001 |
| Science and technology studies | 0.000 | 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 | 0.000 |
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".