Delving into the early Cambrian Cranbrook Lagerstätte of western Canada: an ichnologic analysis
Bibliographic record
Abstract
Abstract The lower Cambrian Cranbrook Burgess Shale-type Lagerstätte (Series 2, Stage 4) occurs within the Eager Formation of southeastern British Columbia, Canada. This deposit consists of claystone intercalated with normally graded mudstone, which has medium silt to very fine-grained sand and disarticulated skeletal debris near the bed bases, recording mostly accumulation from turbidity currents. Well known for its olenelloid trilobites in particular, the site also contains rare soft-bodied fossils, including Tuzoia carapaces and Anomalocaris claws, and low-diversity and low-density suites of ichnofossils. A 2015 systematic field investigation of a 2.65 m interval recovered 12 ichnotaxa and three types of trace fossils left in open nomenclature. The most abundant are Helminthoidichnites tenuis Fitch, 1850, Palaeophycus tubularis Hall, 1847, Diplocraterion isp., and finger-like structures (FLS). These trace fossils form two ichnocoenoses recurring through the studied interval: (1) the Helminthoidichnites tenuis ichnocoenosis, consisting of small trails and shallow burrows, and (2) the Diplocraterion isp. ichnocoenosis, consisting of paucispecific suites of U-shaped burrows, commonly associated with FLS. The FLS contain a diverse range of disarticulated or broken trilobite sclerites and grains coarser than the host sediment and are interpreted as passively infilled burrows, suggesting significant sediment bypass and trapping of transported grains. Overall, the Cranbrook ichnocoenoses do not display a well-defined tiering structure. The trace fossils overall record the activities of a surficial epifauna and a shallow-tier infauna that colonized the sea bottoms during short windows between episodic flows and inhabited dysoxic ( Helminthodichnites tenuis ichnocoenosis) to relatively well-oxygenated ( Diplocraterion isp. ichnocoenosis) outer shelf environments.
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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 | 0.004 | 0.006 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 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".