Mammals from the St. Mary River Formation (Upper Cretaceous), Montana
Bibliographic record
Abstract
ABSTRACT The St. Mary River Formation (Fm) crops out in restricted parts of southwestern Alberta and northwestern Montana. Mammals are poorly known from the formation, but material collected from Alberta has played a role in recognizing an ‘Edmontonian’ Land Mammal Age between the better sampled Judithian (∼79–74 Ma) and Lancian (∼67–65 Ma) land mammal ages. New and well-preserved multituberculate and metatherian material collected from a single locality in the lower third of the St. Mary River Fm of Montana adds complexity to the interpretation of a discrete ‘Edmontonian’ Land Mammal Age. We report here three taxa of multituberculates (Paracimexomys propriscus, sp. nov., Nidimys occultus, gen. et sp. nov., and a primitive ptilodontoid of comparable size to the smallest species of Mesodma Jepsen, 1940 Jepsen, G. L. 1940. Paleocene faunas of the Polecat Bench Formation, Park County, Wyoming. Proceedings of the American Philosophical Society, 83: 217–341. [Google Scholar], and Cimexomys Sloan and Van Valen, 1965 Sloan, R. E. and Van Valen, L. M. 1965. Cretaceous mammals from Montana. Science, 148: 220–227. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar]) and two metatherian taxa (Leptalestes toevsi, sp. nov., and Turgidodon russelli). Paracimexomys propriscus and Turgidodon russelli are probably conspecific with Judithian forms that did not survive to the Lancian. Leptalestes toevsi and Nidimys occultus are taxa unique to the ‘Edmontonian’ but may represent lineages that separated from their closest relatives prior to the Judithian. Lack of Lancian-aspect mammals contrasts sharply with other ‘Edmontonian’ faunas, including an older fauna recovered from the Williams Fork Fm of Colorado, suggesting that the replacement of Judithian mammals by Lancian forms was a complex transition. We tentatively suggest that the Lancian fauna may have expanded into the northern part of the Western Interior in response to the appearance of new terrestrial habitats as sea level fell.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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 teacher head, 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".