The ichnological optimum: enhanced trace fossil diversity in the Cambrian offshore driven by ecology, sedimentation and outcrop
Bibliographic record
Abstract
The trace fossil record provides a valuable archive of the Cambrian Explosion and its variable expressions in different environments. To characterize factors controlling such variability, we present a framework that deconstructs local ichnodiversity into (1) ‘ original ichnodiversity’, reflecting ecology and behavioural diversity; (2) ‘ registered ichnodiversity’, reflecting colonization windows and substrate preservation; and (3) ‘ observable ichnodiversity’, reflecting present-day outcrop quality. An environment with favourable controls on all three levels results in an ichnological optimum , exemplified by environments between storm- and fairweather wave base. We illustrate this with reference to the Cambrian Stage 3 Redalen Member (southern Norway), from which we report 28 ichnogenera. Its depositional environment hosted a diverse assortment of low-diversity communities, indicating that faunal segregation and substrate variability contributed to an elevated original ichnodiversity. Further, non-erosive episodic sedimentation without intervening wave-action extended colonization windows and facilitated preservation, promoting registered ichnodiversity. Finally, thin-bedded heterolithic successions incompletely homogenized by bioturbation are conducive to ichnotaxon identification in outcrop, enhancing observable ichnodiversity. Relative to this Cambrian ichnological optimum, sedimentary controls restricted shallower-marine registered ichnodiversity, while evolutionary controls restricted original ichnodiversity in deeper-marine and tidal flat settings. Future consideration of original, registered and observable fossil records will refine how we decipher spatially heterogeneous evolutionary patterns.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| 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".