PALEOCLIMATIC AND PALEOECOLOGICAL IMPLICATIONS OF A PALEOCENE–EOCENE FOSSIL LEAF ASSEMBLAGE, CHICKALOON FORMATION, ALASKA
Bibliographic record
Abstract
Abstract New collections of a leaf compression-impression paleoflora preserved in fluvio-lacustrine sediments of the upper Chickaloon Formation, south-central Alaska, United States, provide leaf physiognomic climate estimates for the early Eocene in southern Alaska and rare data on plant-insect interactions from a subarctic setting. Thirty-nine broadleaf angiosperm morphotypes occur in a parautochthonous assemblage along with Metasequoia shoots and trunks, compressions of a diverse suite of seeds, monocotyledonous aquatic plants, freshwater gastropods, and inclusion-bearing dispersed amber. Leaf-character derived mean annual temperature estimates (11–14.6 °C) are significantly warmer than Alaska at present and indicate warm temperate conditions at the time of deposition. Leaf-derived mean annual precipitation estimates of ∼110–160 cm/annum are comparable to those from similar-age paleofloras in Arctic Canada and indicate wetter conditions than nearly coeval paleofloras further south in the North American mid-latitudes. Leaf herbivory is rare in the Chickaloon assemblage (∼9% of leaf fragments) as compared to other, lower latitude Eocene assemblages, but exhibits four of the main leaf-damage guilds (hole feeding, margin feeding, surface feeding, and skeletonization). These data provide a rare glimpse at a high-latitude terrestrial forested ecosystem during a global hothouse climate phase and thus have implications in understanding how biogeographic patterning and ecological systems respond to non-analog, warm high-latitude environmental conditions.
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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 | 0.001 | 0.001 |
| 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".