Abstract: Life and times of some Late Cretaceous-Early Tertiary polar forests from northwest Ellesmere Island, Arctic Canada
Bibliographic record
Abstract
During the Mesozoic to Early Cenozoic, greenhouse climate phase forests grew well within the polar circle. These unique polar forest ecosystems fl ourished in a warm, high-latitude environment where trees were subjected to months of unbroken winter darkness followed by continuous daylight in the summer and elevated atmospheric CO2 levels. Analysis of these polar forests is important because they provide a long-term context for the response of modern boreal forest ecosystems to future global climate change; as one scientist succinctly put it, “the past is the key to the future”. In this paper, new Late Cretaceous to Early Tertiary fossil plant sites are described from Emma Fjord and Phillips Inlet, NW Ellesmere Island (paleolatitude of ~78°N). The fossil sites occur in the Campanian/Maastrichtian to Danian Hansen Point Volcanics of the Eureka Sound Group, Sverdrup Basin. This stratigraphic unit is interpreted as originating in a volcanically disturbed, alluvial plain/peat mire setting close to the margins of the paleo-Arctic Ocean. Moderately diverse assemblages of megafl ora (wood and foliage) and palynofl ora occur. Thin section studies of anatomical features in fi ve silicifi ed and calcifi ed fossil wood specimens indicate the presence of three conifer families in this high-latitude environment, the Taxodiaceae, Pinaceae, and Cupressaceae. Foliage assemblages are dominantly composed of taxodiaceous conifers together with cupressaceous conifers, gingkos, angiosperms, and ferns. Taxodiaceous conifers were probably the main source plants for the common amber remains at the two sites. Biometric analysis of tree trunks suggests that the forest canopy was in the order of 15–25 m high. Growth ring studies indicate a cool temperate climate with high year-to-year variability. Traumatic rings indicate the occurrence of sharp frosts towards the end of the growing season. Abundant charcoal remains suggest that these polar forests were frequently disturbed by wildfi re, perhaps related to local volcanism.
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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 | 0.002 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| 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".