Attachment structures in shells from the Ordovician and Silurian of Canada, Europe and Africa
Bibliographic record
Abstract
Shallow pits occur in gastropod and trilobite shells from the Middle Ordovician to Late Silurian of eastern Canada, western Europe and northern Africa. Despite their widespread occurrence, these pits have gone relatively unnoticed in the literature. Individual pits typically are 200-350 μm ovals with a lobate outline, penetrating steeply to a uniform depth of 20-30 μm. The base of the pits are sculptured by an irregular lattice of more deeply penetrating, narrow (~3 μm) fissures that separate less deeply penetrating angular regions that are 5-15 μm in width. Pits always occur in multiples and form an irregular array with no apparent alignment. Adjacent pits typically are spaced more than one pit diameter away (300-500 μm) and they rarely abut one another. Pits appear to be postmortem structures occurring both on the inside and outside of shells. Although the size range and general shape of the pits is similar to some dendrinid microborings described from the Paleozoic, their wide surface aperture suggests that these pits were most likely attachment structures. The rough microsculpturing formed by the fissures at the base of the pits increases the surface area of shell exposed to the tracemaker, a feature that would be advantageous as an anchoring mechanism. These pits differ from named Paleozoic traces attributed to brachiopods and bryozoans (e.g., Podichnus and Ropalonaria) by their shallower penetration, irregular shape, and lack of consistent pit arrangement.
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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 | 0.003 | 0.003 |
| Science and technology studies | 0.002 | 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".