Thermoregulation in late cretaceous marine reptiles of Manitoba
Bibliographic record
Abstract
The thermoregulation of mosasaurs and plesiosaurs have been debated within the field of paleontology for many years, specifically whether these marine reptiles were ectothermic or endothermic. Some degree of endothermy has been proposed for both mosasaurs and plesiosaurs based on histological, morphological, and geochemical methods. Geochemical studies have suggested elevated body temperature in mosasaurs and plesiosaurs compared to ambient seawater temperatures, but the topic remains understudied. For this study, bulk oxygen isotope paleothermometry was used to calculate the body temperatures for Late Cretaceous mosasaurs and plesiosaurs from the Pembina Member of the Pierre Shale in south-central Manitoba. Body temperatures were also calculated for coeval fish and birds (Hesperornis) from the Pembina Member which were used as ectothermic and endothermic ‘end members’, respectively. Before temperatures were calculated, the preservation of 25 fossils specimens were assessed using scanning electron microscope analysis, relative total rare earth element concentrations, principal component analysis of bulk element concentrations, and the difference between the δ18O in the phosphate and carbonate fractions. Using bulk oxygen isotope palaeothermometry, body temperatures were calculated to be 36.4 ± 1.1°C SD for mosasaurs, 42.8 ± 0.3°C for plesiosaurs, 28.1°C for fish and 41.1°C for Hesperornis. Statistical analysis could not be conducted due to the small sample size, but the body temperatures of Manitoba mosasaurs did fall between coeval ectothermic fish and endothermic birds and were consistent with those calculated from other localities. Plesiosaur specimens also possessed elevated body temperatures but exceeded those calculated for both fish and birds as well as those previously determined for plesiosaurs from different localities. The elevated temperatures calculated for the Manitoba plesiosaur specimens may reflect differences in body temperatures between genera or may be the result of diagenetic alteration. The body temperatures calculated for the marine reptiles in this study are elevated compared to ambient seawater temperatures and thus, can be taken as evidence of endothermy in Late Cretaceous Manitoba mosasaurs and plesiosaurs.
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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 | 0.000 |
| 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".