Analytical and supplemental data from: Ammonites as paleothermometers: Isotopically reconstructed temperatures of the Western Interior Seaway track global records
Bibliographic record
Abstract
Ammonites are externally shelled cephalopods that were common in the North American Western Interior Seaway (WIS), and as they grew their aragonitic shells via accretion, they recorded aspects of their environment in the stable isotopic composition of their shells. While the mobility of ammonites may complicate efforts to reconstruct temperatures from their shells, they remain a valuable potential target for paleothermometry. In this study, we reconstruct the spatial and temporal variability of WIS temperatures using a suite of ammonites (n=113) covering the last 25 million years of the Cretaceous and spanning from the Canadian WIS to the Mississippi Embayment. We present a temporally high-resolution (~0.6 Ma) oxygen isotope record from these ammonites that indicates cooling temperatures in the WIS (of comparable magnitude (~18°C +/- 4°) to the temperature change seen in global studies, most notably cooling from the Cretaceous Thermal Maximum in the Turonian until the Late Maastrichtian. Studies disagree regarding the development and strength of a latitudinal (pole-to-equator) temperature gradient during the Cretaceous; our results do not support the presence of a latitudinal temperature gradient in the WIS. Our data indicate that paleolatitude and temperature have either no correlation, or a correlation in the opposite direction from the expected gradient. We do not observe any bias driven by ammonite morphology in our data, though we suggest that researchers consider the effects of taxonomy and ecological bias on their temperature records. As our ammonite δ18O record matches the direction and magnitude of global temperature reconstructions, our data imply that ammonites are valuable targets for paleothermometry.
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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 | 0.002 | 0.014 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.005 | 0.009 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.004 | 0.002 |
| Open science | 0.003 | 0.003 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.596 | 0.240 |
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".