Review of Stagodontidae (Mammalia, Marsupialia) from the Judithian (Late Cretaceous) Belly River Group of southeastern Alberta, Canada
Bibliographic record
Abstract
Although stagodontid marsupials are among the most distinctive mammals of Late Cretaceous age in North America, there remain significant gaps in knowledge of their dental anatomy, particularly that of the stratigraphically oldest genus, Eodelphis Matthew, 1916. We report here on stagodontid specimens from the Judithian Belly River Group of southeastern Alberta, Canada, that document what was until now previously unknown parts of the upper and lower premolar dentition of Eodelphis browni Matthew, 1916 and Eodelphis cutleri (Smith Woodward, 1916). The new information further confirms the distinctiveness of both nominal species of Eodelphis, and bolsters previous hypotheses suggesting a close phylogenetic relationship between E. cutleri and the advanced stagodontid Didelphodon Marsh, 1889. Although the new specimens from Alberta suggest that the problematic holotype of “Boreodon matutinus” Lambe, 1902 is an upper third premolar, a referral to Eodelphis cannot be made with confidence and the name should continue to be treated as a nomen dubium. Lastly, we report the first occurrence of Didelphodon in strata of the Belly River Group, extending the geological age of the genus into the Judithian, co-eval with species of Eodelphis, and suggesting a significant prior and as yet undiscovered evolutionary history.
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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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.002 | 0.001 |
| Bibliometrics | 0.016 | 0.020 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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".