The Canadian fossil record supports anagenesis in <i>Triceratops</i> (Ornithischia, Ceratopsia)
Bibliographic record
Abstract
Evolution of the ceratopsid dinosaur Triceratops has been hypothesized to have proceeded anagenetically, with the geologically older Triceratops horridus Marsh, 1889 having directly given rise to the younger Triceratops prorsus Marsh, 1890. This evolutionary scenario is based primarily on the upper Maastrichtian fossil record of the Hell Creek Formation in Montana. The Canadian fossil record affords an opportunity to test this hypothesis beyond the geographic bounds where it was originally developed. The Canadian strata (lower Scollard Formation of Alberta and Frenchman Formation of Saskatchewan) are roughly contemporaneous with the upper third of the Hell Creek Formation where Triceratops prorsus is found. On the anagenesis hypothesis, the Canadian strata should, therefore, uniquely contain that species. Our exhaustive survey of the Canadian Triceratops material, supported by cladistic and ordination analyses, confirms the presence of a single species, Triceratops prorsus, in Canada, yielding robust support for the anagenesis hypothesis conceived for the genus.
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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 | 0.002 |
| Science and technology studies | 0.002 | 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) | 0.003 | 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".