Anatomically-preserved cordaitalean trees from Lower Pennsylvanian (Langsettian) dryland alluvial-plain deposits at Joggins, Nova Scotia
Bibliographic record
Abstract
Recent discoveries at Joggins, Nova Scotia have altered our understanding of the Pennsylvanian tropical biome. Of particular significance has been the recognition of seasonal dryland ecosystems, compositionally distinct from the peat-forming wetland rainforests. Here I describe two anatomically-preserved fossil plant specimens from dryland alluvial plain facies. The first specimen, Mesoxylon cf. sutcliffi i, is previously unknown from Joggins. It is a septate cordaitalean axis with mesarch leaf traces and a non-sympodial vasculature. Where found as isolated blocks, the secondary xylem of this plant has previously been classified as Dadoxylon recentium. The axis exhibits subtle growth interruptions suggestive of tropical rainfall seasonality, while associated traumatic zones may record fire-damage. The second specimen is a Dadoxylon stump rooted within well-drained floodbasin soils. It confirms earlier conjecture, based on parautochthonous assemblages, that cordaitalean trees grew in inter-channel areas. Together these new specimens improve our knowledge of the composition and ecology of seasonal dryland vegetation at Joggins. RÉSUMÉ Des découvertes récentes à Joggins (Nouvelle-Écosse), ont modifié notre compréhension du biome tropical pennsylvanien. La reconnaissance d'écosystèmes de milieux arides saisonniers aux compositions distinctes des forêts tropicales humides ayant formé des tourbières, s'avère particulièrement importante. Je décris aux présentes deux spécimens préservés de plantes fossiles anatomiquement provenant du faciès d'une plaine alluviale de milieu aride. Le premier spécimen, un Mesoxylon cf. sutcliffi i, était auparavant inconnu à Joggins. Il s'agit d'un axe cordaitaléen cloisonné comportant des cicatrices foliaires à arc moyen et une vasculature non sympodiale. Lors de sa découverte sous forme de blocs isolés, on avait précédemment classifié le xylème secondaire de cette plante en tant que Dadoxylon recentium L'axe présente des interruptions de croissance subtiles évoquant des chutes de pluie tropicales saisonnières, tandis que les cernes traumatiques associés pourraient témoigner de dommages causés par le feu. Le second spécimen est une souche de Dadoxylon qui plongeait ses racines à l'intérieur des sols d'un bassin de crue bien drainé. Il confirme une conjecture antérieure, basée sur des assemblages parautochtones, supposant que les arbres cordaitaléens aient poussé dans des secteurs situés entre des chenaux. Ces deux nouveaux spécimens améliorent notre connaissance de la composition et de l'écologie de la végétation saisonnière des milieux arides à Joggins. [Traduit par la rédaction.]
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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 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 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".