Fossil eggs and eggshell from the lowermost Two Medicine Formation of western Montana, Sevenmile Hill locality
Bibliographic record
Abstract
In the last 30 years, the Two Medicine Formation of western Montana has provided a wealth of information about dinosaur reproductive biology. Here, we describe a fossil egg-bearing stratum that occurs approximately 105 m above the base of the formation. This site in the Sevenmile Hill outcrops south of Choteau, Montana, lies immediately above a volcanic tuff and bentonite, dated as 80.0 Ma. Spherulitic eggshells from a quarry at this locality are similar to Spheruprismatoolithus candensus CitationBray, 1999, which were assigned to the oofamily Prismatoolithidae. However, we refer this eggshell to the Spheroolithidae CitationZhao, 1979, as Spheroolithus choteauensis, oosp. nov. The quarry also produced Triprismatoolithus stephensi, oogen. et oosp. nov. These symmetrical 30 mm × 75 mm prismatic eggs exhibit three structural layers of calcite and round tubercles on the shell surface. Four additional ootaxa occurred at the First Find Microsite (OTM 99-19): Prismatoolithus hirschi, oosp. nov.; Tubercuoolithus tetonensis, oogen. et oosp. nov.; Continuoolithus canadensis CitationZelenitsky et al., 1996; and Krokolithes CitationHirsch, 1985. Spheroolithus choteauensis, T. stephensi, P. hirschi, T. tetonensis, and Krokolithes are unique to the lowermost Two Medicine Formation, whereas C. canadensis may occur elsewhere in the middle and upper strata of the Two Medicine and Oldman formations of Montana and Alberta, respectively. Although poorly represented by dinosaur osteological remains, the lower Two Medicine Formation locality yields egg types that suggest a significant difference in faunal composition compared to the middle and upper portions of the formation.
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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) | 0.002 | 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".