Anatomy, affinities, and evolutionary implications of new silicified stems of Sphenophyllum Brongniart, 1828 from the early Carboniferous (Mississippian) of France and Germany
Bibliographic record
Abstract
Sphenophyllum Brongniart, 1828 is the best-known representative of Sphenophyllales, an extinct order of small plants belonging to the Sphenophytes, the group that contains extant horsetails. Sphenophyllum is known from the Devonian to the Triassic, but most specimens are late Carboniferous in age and the anatomy of specimens present at other times is poorly known because most are preserved in compression/impressions. The Lower Carboniferous (Tournaisian) deposits of Montagne Noire in France and Thuringia in Germany contain impressions attributed to Sphenophyllum but also a few rare permineralized specimens. In this study, we describe in detail the anatomy of these specimens and compare them to other anatomically preserved Sphenophyllum species, as well as to the impressions already described in both areas. The new specimens show different developmental stages, some have a little amount of wood while the others only have primary tissues. Two specimens are branching. All are assigned to Sphenophyllum insigne Williamson. While Late Carboniferous Sphenophyllum produced a wood with a very peculiar anatomy (very large tracheids, axial system of parenchyma), that of the oldest Sphenophyllales (Devonian-Early Carboniferous) seems to be simpler and probably had different hydraulic and mechanical properties.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".