Range and radiation of Cambrian Trilobites
Bibliographic record
Abstract
Revealing the patterns and drivers of diversity in the Cambrian requires an understanding of distribution. On a dynamic Earth with uncertain palaeogeography, the understanding of range and diversity requires novel methodology and approaches. Trilobites, an extremely diverse group of arthropods, underwent important shifts in diversity and morphology throughout the Cambrian. However, the mechanisms driving their global dispersal and diversification during the early Palaeozoic remain inadequately understood. Persistent issues in studying the facilitators of distribution include morphological and life history constraints, e.g. the impact of benthic or pelagic larval stages. This uncertainty is compounded by the limitations of current palaeogeographical reconstructions. To address these issues, the Trilobite Biogeography and Ecology working group (TRiBE) applied a novel approach to geography and reconstructed trilobite biogeographical patterns associated with their initial global radiation from throughout the Cambrian. Using phylobiogeographic methods, with the Paterson et al (2019) phylogeny, we took three approaches to area establishment and compared the resulting patterns. The results, strengthened through robust comparison of area establishment, provide insights into Cambrian trilobite ancestral geographical ranges, the frequency and type of allopatric speciation events, and the connectivity between different regions during this critical phase of euarthropod evolution. Comparison between palaeogeography, climate, and marine connectivity are examined as facilitators of a global trilobite distribution and the specialisation of the group throughout the Cambrian. This study aims to both make comment on the evolutionary success of early euarthropods, but also to highlight the influence of geographical assumptions on interpretation.
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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 | 0.001 |
| 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".