The development and shell microstructure of the pseudodeltidium and interarea in thecideide brachiopods
Bibliographic record
Abstract
Abstract: This study examines the development of the delthyrium, pseudodeltidium and interarea, their growth during the early juvenile stages of ontogeny and the extrapolation of morphology from adult shells to the probable juvenile state. Examination of the development and shell microstructure of the cardinalia of early juvenile thecideide brachiopod ventral valves from Jurassic, Cretaceous and Holocene specimens suggests that the delthyrium develops early in ontogeny and that the initial development of the pseudodeltidium precedes that of the interarea. Also, until the interarea is formed, the postero‐lateral flanks of the ventral umbo are palintropic. The development of the interarea can be seen to be a consequence of the lateral extension of the early juvenile hinge line. Initially, the pseudodeltidium consists solely of a thin plate of primary shell material. Comparison of the morphology of the pseudodeltidium of early juveniles with that of adults suggests that the initially curved lateral profile of the pseudodeltidium is retained, or even accentuated, in the ontogeny of lacazellines, but in all thecidellinines, with the exception ofPachymoorellinaandMinutella, following the appearance of the interarea, the pseudodeltidium becomes flattened and often appears continuous with the interarea. However, we do not support any proposal that suggests that, in thecideides, only those forms in which the delthyrium is closed by a dorsally convex plate should be considered to possess a pseudodeltidiumsensu stricto, mainly because of physiological differences and the prospect of possible taxonomic confusion in the future. Instead, we propose the termplanodeltidiumfor a flat pseudodeltidium, typically developed in the thecidellinines, andrugideltidiumfor a convex pseudodeltidium, typically developed in the lacazellines, but also inPachymoorellinaandMinutella. Despite the presence of a rugideltidium, we believe the affinities ofMinutellaare more strongly with the thecidellinines and have included it in the new subfamily Minutellinae of the family Thecidellinidae.
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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 | 0.000 |
| 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".