Applications of strontium concentrations and isotopes preserved in vertebrate enamel and enamel-like tissues to paleoecology studies of Silurian conodonts from Gotland, Sweden, and Cretaceous Dinosaurs and Plesiosaurs from Alberta, Canada
Bibliographic record
Abstract
Paleoecology is faced with the challenge of determining the behaviour of extinct animals without direct observation. Geochemical approaches offer one of the most promising avenues to study paleoecology problems such as potential migratory patterns. While original biochemical signals are often obscured in fossilized tissues as a result of diagenesis, tooth enamel is an exception due to its very high mineral content and low porosity. Though there are many potential biological signals preserved in fossil enamel, this thesis focused on the trace element strontium. By analyzing strontium isotope ratios preserved in the enamel of terrestrial dinosaurs, possible migratory behaviours were examined in both hadrosaurs and ceratopsians found at Dinosaur Provincial Park in the Late Cretaceous Dinosaur Park Formation of Alberta, Canada. The movements of a hadrosaur individual were determined to extend beyond the Dinosaur Provincial Park area to a location just under 100 km to the east of the park. In contrast, a herd of ceratopsians preserved in a bonebed were shown to have travelled as far as 200 km from either the north or west. Strontium isotope ratios were also examined in the enamel of plesiosaurs and enamel-like tissues of conodonts to determine if either group inhabited freshwater habitats. Plesiosaur teeth collected from fluvial deposits of the Dinosaur Park Formation were found to largely preserve a terrestrial signal, suggesting some plesiosaurs may have primarily inhabited freshwater environments. Conodont elements from Silurian marginal marine deposits in Gotland, Sweden were also examined with a focus on potential differences through ontogeny. The results confirmed the conodont taxa Ozarkodina confluens lived exclusively in marine settings and did not spawn or spend time in coastal freshwater environments. Finally, Sr/Ca and Ba/Ca ratios were analyzed in an entire conodont community from the Silurian of Gotland, Sweden. Results revealed convincing evidence for trophic partitioning between co-occurring conodont taxa. Compositional variations were observed between the two main tissues found in conodont crowns, white matter and lamellar tissue. These tissues occur in different proportions in different taxa, and these proportions need to be kept in mind when interpreting their geochemical data.
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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 | 0.003 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 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".