Inferring the environmental conditions present during early tetrapod terrestrialization from skeletal [delta]18O values
Bibliographic record
Abstract
To test the extent of marine influence in the Joggins Formation, Nova Scotia, Canada and the possible habitat segregation and the net moisture balance at the Red Hill roadcut exposure of the Duncannon Member of the Catskill Formation in Pennsylvania, phosphatic fossils from both locations were analyzed to determine local and/ or regional changes in the oxygen isotopic composition of local surface waters. Marine to brackish taxa are present within the Joggins Formation, but disagreement exists over the degree of marine influence during deposition. In this study, the [delta]18Owater values calculated for sections of the Joggins Formation compared with typical values for Carboniferous marine water don't reflect fully marine conditions but are consistent with a brackish setting in which seawater mixed with freshwater in the Cumberland Basin during the deposition of the Joggins Formation. Evidence of net evaporative conditions present in the sedimentological and paleontological record at the Red Hill floodplain suggest [delta]18O of water would be high and variable. Variability in [delta]18O across the floodplain show no general trends toward net evaporative conditions. However, variability within individuals does reflect variation in aquatic conditions, not artifacts related to sample types. Observations presented in this study provide independent constrains on two windows into the transition from fish to fully terrestrial vertebrates.
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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 | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".