Ultrastructure of the coenecium of <i>Cephalodiscus</i> (Hemichordata: Pterobranchia)
Bibliographic record
Abstract
The ultrastructure of the coenecia of Cephalodiscus (Cephalodiscus) hodgsoni Ridewood, 1907, Cephalodiscus (Idiothecia) nigrescens Lankester, 1905, and Cephalodiscus (Orthoecus) densus Andersson, 1907 was characterized using light microscopy, transmission electron microscopy, and scanning electron microscopy. The coenecium of Cephalodiscus is composed of layers of coenecial material of variable thickness laid down one upon the next and separated by sheets. Thick fusellar-like layers (up to 160 μm thick) and thin cortical-like layers (down to 15 nm thick) are present, but do not form two distinct components. Instead, a continuum exists in the thickness and shape of these layers. At the ultrastructural level, both fusellar-like and cortical-like layers are composed of thin (16–23 nm) long and straight fibrils, similar to the fibrils described in extant Rhabdopleura Allman, 1869. In C. densus, fibrils in the outer secondary deposits show a parallel arrangement, similar to the arrangement of fibrils in the graptolite eucortex. Although similarities in the shape and arrangement of growth increments between Cephalodiscus, Rhabdopleura, and graptolites probably reflect homologous zooidal behaviors and secretion mechanisms, differences at the ultrastructural level show that fibril types and fibril arrangement can evolve independently from larger scale features of the coenecium.
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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".