Cambrian Bivalved Mandibulates (Arthropoda) from the Burgess Shale: Ecology and Evolution
Bibliographic record
Abstract
The fossil record shows that metazoans experienced a rapid radiation soon after their origin, an evolutionary event termed “the Cambrian Explosion”. The 506-million-year-old (Cambrian, Wuliuan) Burgess Shale formation in British Columbia (Canada), illustrates the aftermath of this event thanks to its exceptionally preserved fossil material. This material contains soft tissues, usually scarce in the fossil record, that show an extraordinary diversity of metazoans, among them arthropods, dominant in both diversity and abundance. Arthropods are the most diverse and disparate metazoan group today and have a long evolutionary history with multiple extinct Cambrian groups. Among these, ‘bivalved arthropods’ are characterized by a carapace covering the head and thorax. Their affinities have remained problematic, but recent discoveries suggest a position within mandibulates, the arthropod group which currently includes myriapods and pancrustaceans. A holistic morphological exploration of this group, including details on key anatomical areas as well as further assessing their mandibulate affinities, though, are still lacking. This thesis, then, aims to expand their diversity, reconstruct their morphology and ecology, and understand their evolutionary history primarily based on original discoveries from the Burgess Shale formation. The first three chapters describe new species from the Marble Canyon locality in Kootenay National Park (BC):
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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) | 0.002 | 0.001 |
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".