Troodontid specimens from the Cretaceous Two Medicine Formation of Montana (USA) and the validity of <i>Troodon formosus</i>
Bibliographic record
Abstract
Abstract In 1855, Ferdinand Hayden collected a single tooth from the Judith River badlands of central Montana. Joseph Leidy named this specimen the following year as Troodon formosus. We describe troodontid material from the coeval Two Medicine Formation of Montana that compares closely to the recently resurrected and previously synonymized Stenonychosaurus inequalis from the lower Dinosaur Park Formation of Alberta. We uphold that synonymy but recognize T. formosus as the senior synonym. Troodon formosus is distinguished from other troodontids by a maxilla with an anteriorly more broadly rounded maxillary fenestra, low-angled nasal process with stepped anterior portion, large palatal shelf, and 23 teeth; more pronounced basioccipital tubera; L-shaped to triangular frontal; and relatively shorter metatarsal III with convex to flat anterior face at maximum breadth. Phylogenetic analysis places T. formosus within the Troodontinae, a clade with poor within-group resolution. The T. formosus holotype was diagnostic at time of description. Despite numerous complications over the taxon’s long history, the original name of 1856 has come to encompass a robust and specific species concept despite originally fragmentary material. Troodon formosus best satisfies the International Code of Zoological Nomenclature’s tenants of priority and stability. Recent proposals to re-establish Stenonychosaurus inequalis as the proper name encounter an equally problematic and undiagnostic type specimen. Instead of either of these types, we propose that material from the Two Medicine Formation (Museum of the Rockies, MOR 553) would best serve as a neotype for Troodon formosus.
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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) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".