Plants, a Yardstick for Measuring the Environmental Consequences of the Cretaceous-Tertiary Boundary Event
Bibliographic record
Abstract
Reactions registered by plant communities to the Cretaceous-Tertiary (K-T) boundary cometary impact event include extinctions, killing events, shifts in the relative number and abundances of taxa, and, for some taxa, an apparent insensitivity to imposed stresses. All these provide yardsticks to measure the extent of impact-generated environmental perturbations: extinctions by their magnitude and selectiveness, killing events by their geographic extent, and the survivors by their varying sensitivities to the boundary event as reflected in trends in their relative abundances and distribution. Information has been assembled from localities in western Canada and Montana that suggests: most plant extinctions involved what were likely zoophilous (animal-pollinated) angiosperms; under story vegetation may have survived the event; there was extensive destruction of the forest canopy on a continental scale; and there was a variable response to the K-T boundary event by what were likely wind-pollinated angiosperms. Resume Les repercussions sur les peuplements de vegetaux enregistrees dans les couches rocheuses lors de l'impact meteoritique de la limite Cretace-Tertiaire (K-T) vont de l'extinction d'especes, a l'annihilation de masse, aux fluctuations dans l'abondance relative des taxons et, pour certains taxons, a l'apparente insensibilite face aux contraintes ambiantes. Autant de facon de mesurer l'etendue des repercussions des perturbations environnementales engendrees par des impacts : les extinctions d'especes, par leurs etendues et leurs selectivites, les annihilations de masse par leurs etendues geographiques et, les survivants, par la variation de leur sensibilite specifique a l'evenement limite, tel qu'il est reflete dans leur tendance, leur abondance et leur distribution relatives. Des donnees recueillies dans differentes localites de l'Ouest canadien et de l'etat du Montana indiquent que la plupart des extinctions de vegetaux ont affecte des especes d'angiospermes probablement zoophiles (pollinises par des animaux); que les especes du sous-etage forestier ont pu survivre a l'evenement; qu'il y aurait eu destruction massive du couvert forestier a l'echelle du continent, et; que les reactions a l'evenement de la limite K-T des angiospermes pollinises par le vent ont ete variees.
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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 | 0.003 | 0.007 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.007 | 0.004 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.011 | 0.002 |
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".