The Giant Marine Gastropod <i>Campanile Giganteum</i> (Lamarck, 1804) as a High‐Resolution Archive of Seasonality in the Eocene Greenhouse World
Bibliographic record
Abstract
Abstract Giant gastropods are among the largest mollusks in the fossil record, but their potential as paleoseasonality archives has received little attention. Here, we combine stable isotope and trace element analyses with microscopic observations and growth modeling on shells of two species of the gastropod genus Campanile: the extinct Campanile giganteum from Lutetian (~45 Ma) deposits in the Paris Basin (France), the longest gastropod known from the fossil record, and its modern relative Campanile symbolicum from southwestern Australia. The C. giganteum shells contain original aragonite and have pristine nacre in their apertures. We show that these gastropods attained growth rates exceeding 600 mm/year along their helix, depositing over 300 cm3 aragonite per year. High growth rates and excellent preservation make C. giganteum excellent archives for reconstructing environmental change at high (potentially daily) temporal resolution, while providing enough material for methods such as clumped isotope analysis. Growth models show that Campanile gastropods grew nearly year‐round, albeit slower in winter. Stable oxygen isotope ratios in modern C. symbolicum faithfully record a seasonal variability of 18–25°C in sea surface temperature, only failing to record the coolest winter temperatures (down to ~16°C). Similarly, C. giganteum specimens likely record a nearly complete seasonal temperature range. Assuming constant sea water isotope composition, their oxygen isotope seasonality of up to 2.5‰ would translate to a Lutetian temperature range of 21–32°C in the Paris Basin. We hypothesize that these high and seasonally variable temperatures formed the breeding ground for the Lutetian shallow marine biodiversity hotspot in the Paris Basin.
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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 | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".