A Macroneuropteris scheuchzeri tree preserved in growth position in the Middle Pennsylvanian Sydney Mines Formation, Nova Scotia, Canada
Bibliographic record
Abstract
Fossil plants preserved in growth position provide important insights into the architecture and ecology of ancient plants. Here I describe an upright tree of Macroneuropteris scheuchzeri rooted above the Point Aconi Coal in the Middle Pennsylvanian Sydney Mines Formation of Nova Scotia – the first example of an autochthonous pteridosperm described in the literature. The fossil tree has a sharply tapering trunk surrounded in its lower part by a large number of downward-recurved senescent petioles, which form a skirt. Petioles borne in an upright or horizontal position, interpreted as fronds that were still photosynthetically active when buried, are confined to the uppermost preserved part of the tree. Adapted to growth in rapidly aggrading coastal wetlands, the skirt of Macroneuropteris scheuchzeri probably acted to prop up the trunk while additionally trapping large mounds of mud around the base of the tree and stabilizing coastal wetlands. The tree had a sprawling habit and a maximum height of about 2 m. Similar, but smaller, trees found in adjacent beds probably represent juvenile specimens of the same species. RÉSUMÉ Les végétaux fossiles conservés dans leur position de croissance fournissent des renseignements précieux sur l’architecture et l’écologie des plantes anciennes. Je décris dans le présent document un Macroneuropteris scheuchzeri droit enraciné au‑dessus de charbon de Point Aconi dans la Formation du Pennsylvanien moyen de Sydney Mines, en Nouvelle‑Écosse – premier exemple de ptéridosperme autochtone décrit dans les ouvrages. L’arbre fossile possède un tronc nettement effilé entouré dans sa partie inférieure d’un grand nombre de pétioles sénescents recourbés vers le bas, qui forment une jupe. Des pétioles en position verticale ou horizontale, interprétés comme des frondes qui étaient encore actives sur le plan photosynthétique au moment de l’enfouissement, sont confinés à la partie la plus élevée de l’arbre conservée. Adaptée à la croissance dans les milieux humides côtiers d’alluvionnement rapide, la jupe du Macroneuropteris scheuchzeri servait probablement à maintenir le tronc et permettait en même temps d’emprisonner de gros monticules de boue autour de la base de l’arbre et de stabiliser les milieux humides côtiers. L’arbre, qui avait tendance à s’étendre, atteignait une hauteur maximale d’environ deux mètres. Des arbres semblables mais plus petits découverts dans des couches adjacentes représentent probablement de jeunes spécimens de la même espèce. [Traduit par la redaction]
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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 | 0.001 |
| Science and technology studies | 0.003 | 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) | 0.001 | 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".