Petalophyllites speirsiae gen. et sp. nov. (Marchantiophyta: Fossombroniales), a fossil liverwort gametophyte from the Paleocene of Alberta, Canada
Bibliographic record
Abstract
Abstract: Although liverworts (Marchantiophyta) are postulated to be one of the oldest lineages of land plants, their documented fossil record is sparse. This study describes five new fossil liverwort gametophytes, one of which bears antheridia, from the Paleocene Paskapoo Formation of Alberta, Canada. The thalli are bilaterally symmetrical, with two undissected wings that bear oppositely arranged dorsal lamellae. One specimen is dichotomously branched, and one bears clusters of antheridia along the midrib area of its dorsal surface. These characters are consistent with those of extant Petalophyllum (Fossombroniales: Petalophyllaceae), and the genus Petalophyllites gen. nov. (Fossombroniales: Petalophyllaceae) is here erected for these fossils. They are the first representatives of Petalophyllaceae and the Fossombroniales from the fossil record. Most of the specimens are in growth position. Their geologic setting and associated fossils indicate that Petalophyllites lived at the margin of a lake or pond in a habitat that may have been intermittently dry, as is also common in extant species of Petalophyllum. The well-preserved thalli and antheridia of these fossils, and their well-documented middle Paleocene age, provide new evidence of liverwort diversification at the dawn of the Cenozoic Era.
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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 | 0.002 | 0.002 |
| Science and technology studies | 0.003 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".