Tooth histology in the cretaceous ichthyosaur <i>Platypterygius australis</i>, and its significance for the conservation and divergence of mineralized tooth tissues in amniotes
Bibliographic record
Abstract
Ichthyosaurs are an extinct group of secondarily aquatic reptiles that show ligamentous tooth attachment to the jaw in some derived forms. Here, we provide a modern description of tooth histology in ichthyosaurs, using Platypterygius australis, a large ichthyosaur from the Cretaceous of Australia. Our study supports evolutionary conservation of the principal mineralized tooth tissue types in amniotes with ligamentous tooth attachment: enamel, dentine, cellular, and acellular cementum. This is the first time that the latter tissue has been located in ichthyosaurs. Vascularized cementum (osteocementum) is reduced or absent in amniotes in which the teeth are ankylosed to the jaw bone, such as basal ichthyosaurs, and raises questions regarding the function of this tissue and the potential developmental or selective conditions leading to its convergent evolution.
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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 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".