Ichnological evidence for the Cambrian explosion in the Ediacaran to Cambrian succession of Tanafjord, Finnmark, northern Norway
Bibliographic record
Abstract
Abstract The Ediacaran to Cambrian transition of the Digermul Peninsula consists of an ichnologically rich, thick, conformable, shallow marine siliciclastic succession that crosses the Neoproterozoic–Cambrian boundary. The Tanafjord section has been independently dated by published palynological and new body fossil discoveries. As is also observed at the current Global Stratotype Section and Point (GSSP) for the Ediacaran–Cambrian boundary at Fortune Head in Newfoundland, Canada, there is a marked increase in burrow size and inferred behavioural diversity around the inferred boundary level at a surface without a significant hiatus. The diversity of this trace fossil assemblage presents an opportunity to compare the ichnological first appearance datums between the GSSP and another sedimentologically similar, but palaeogeographically remote, succession. We found that the first appearance datums of taxa in Finnmark broadly support the definition and stratigraphic extents of the Harlaniella podolica , Treptichnus pedum, Rusophycus avalonensis and Cruziana tenella zones. Our work shows that there is a marked increase in ichnodiversity in the lowermost Fortunian, mostly in the form of shallow tier traces. The main post-Fortunian ichnological innovation is the evolution of bulk sediment deposit feeding that is first evidenced by spreiten burrows at around the base of Cambrian Stage 2 in both the GSSP and in the Tanafjord section. Supplementary material: Additional images of trace fossils from the studied section are available at https://doi.org/10.6084/m9.figshare.c.3462561
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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 | 0.002 | 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) | 0.002 | 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".