Palm fronds from western Canada are the northernmost palms from the Late Cretaceous of North America and may include the oldest Arecaceae
Bibliographic record
Abstract
Palm leaf fossils are common from Late Cretaceous floras in the United States, but Late Cretaceous Canadian palm records are limited largely to Nanaimo Group strata of British Columbia, with only anecdotal records from east of the Rocky Mountains. Here we report Late Cretaceous leaf fossils from Alberta and Saskatchewan, Canada. Segment angles with the rachis or costa are investigated as an additional character to distinguish costapalmate from pinnate and entire-pinnate palm leaves. The leaf fossils from Alberta and Saskatchewan represent costapalmate-palms (Sabalites), in contrast to the relatively common entire-pinnate palm fossils known from the Coniacian–early Campanian lower Nanaimo Group of British Columbia (e.g., Geonomites imperialis; potentially the oldest known North American palm) and the Campanian Two Medicine Formation of Montana (cf. Phoenicites). The presence of fossil palms in the Campanian to Maastrichtian of Alberta and Saskatchewan constrains climate reconstructions for the Late Cretaceous high mid-latitudes of North America (c. 55° N) to exclude significant freezing episodes. Additionally, we update the nomenclature for G. imperialis, renaming it as a species of Phoenicites, and briefly consider its value to understanding the evolution of pinnate palms. Further, we challenge the interpretation of Sabalites magothiensis as a costapalmate species and reassess the age of S. carolinensis as late Campanian.
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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 | 0.003 | 0.004 |
| Science and technology studies | 0.005 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.008 | 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".