Early colonization of the deep-sea bottom—The protracted build-up of an ecosystem
Bibliographic record
Abstract
Our understanding of the patterns and processes behind the evolution of deep-marine ecosystems is limited because the body-fossil record of the deep sea is poor. However, that gap in knowledge may be filled as deposits are host to diverse and abundant trace fossils that record the activities of benthic deep-marine organisms. Here, we built a global dataset of trace-fossil occurrences from a comprehensive survey of 720 Ediacaran-Devonian units and show that the establishment of a modern-style deep-marine benthic ecosystem was protracted and coincident with global cooling and increase in oxygenation during the Ordovician. The formation of open burrows may have increased bioirrigation in the uppermost sediment zone, promoting ventilation and generating an ecosystem engineering feedback loop between bioturbation and pore-water oxygenation. Sharp changes in deep-marine bioturbation during the Devonian may have originated from oxygen variations resulting from climate-controlled oceanic circulation.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".