Fern Macroflora Identified in the Basal Danian of the Raton Formation Supports Palynological Signal of a Widespread “Postdisaster” Fern Flora
Bibliographic record
Abstract
Premise of research. From a purely palynological perspective, lowest Danian fern-dominated assemblages of the Williston Basin (North Dakota and southwestern Saskatchewan) and the Raton Basin (northeastern New Mexico and southeastern Colorado) appear indistinguishable, although this perspective has yet to be corroborated by macrofloral studies across this same region. No ferns have been collected from the lowest Danian barren series of the Raton Formation in more than a century, and this section remains sparsely sampled. Methodology. New collections of fossil ferns from the basal portion of the barren series or informal middle member of the Raton Formation, which directly overlies the K/Pg boundary, are compared with contemporaneous assemblages in other North American depositional basins. Pivotal results. Dennastra sorimarginata McIver and Basinger (Dennstaedtiaceae Lotsy) and Woodwardia arctica (Heer) Brown (Blechnaceae Newman) that produce Cyathidites diaphana (Wilson and Webster) Nichols and JL Brown and Laevigatosporites haardtii (Potonié and Venitz) Thomson and Pflug, respectively, are recognized as characteristic ferns in the basal portion of the barren series, in addition to Osmunda macrophylla Penhallow. Conclusions. In accordance with palynological perspectives, lowest Danian fern macrofossil assemblages from the Raton Basin support the concept of a geographically widespread “postdisaster” pteridophyte flora represented predominantly by Dennstaedtiaceae and Blechnaceae, with other minor components of more northern assemblages. The enigmatic hypothesis of a landscape dominated by anemiaceous or schizaeaceous ferns is rejected on the basis of this new evidence, which suggests that Cyathidites diaphana–producing dennstaedtiaceous ferns were the K/Pg boundary “disaster taxon” and among those that flourished in the Raton Basin.
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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 | 0.000 |
| 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".