Ichnology and palaeobiology of <i>Phoebichnus trochoides</i> from the Middle Jurassic of north‐east England
Bibliographic record
Abstract
Abstract Phoebichnus trochoides is a large, radiating trace fossil most commonly found in shallow marine siliciclastic deposits. The structure consists of a central boss from which extend numerous, lined, radiating burrows which have an active fill. Serial grinding and modelling techniques allow the full three‐dimensional morphology of Phoebichnus trochoides to be constructed for the first time. Three‐dimensional models of the trace fossil demonstrate that the central zone is composed of stacked disc‐shaped layers. The structure is inferred to result from collapse of sediment below a surficial cone created by the trace‐maker from excavated sediment produced during burrowing. The fill of the radial burrows is herein determined to be composed of angle of repose laminae that are inclined towards the central zone rather than the meniscate backfill documented in the ichnogeneric diagnosis and all subsequent descriptions. The structure of the fill resulted from the trace‐making organism filling its burrows from a dwelling position close to the central boss, probably with material excavated from other parts of the burrow system. This study also reports for the first time subtle conical structures above the radial galleries that are inferred to result from collapse cone feeding. The new fully three‐dimensional data set created of the burrow and the near‐burrow environment allows for a new palaeobiological understanding of the burrow, which suggests that a crustacean trace‐maker is most likely.
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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 | 0.001 |
| Science and technology studies | 0.001 | 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) | 0.003 | 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".