Evolutionary Tempo and Mode of Triceratops for the Uppermost Masstrichtian Frenchman Formation of Southern Saskatchewan
Bibliographic record
Abstract
Previous work regarding the upper Maastrichtian Hell Creek Formation of Montana has hypothesized that two temporally separated species of Triceratops were anagenetically related, with the older T. horridus having directly given rise to the younger T. prorsus.However, this work was limited in geographic scope, and only briefly considered the many known skulls of Triceratops found outside the formation.Several such skulls of varying completeness have been found in the uppermost Maastrichtian Frenchman Formation of southern Saskatchewan over the last century, and provide a crucial test of the anagenesis hypothesis.Given that the Frenchman Formation was deposited contemporaneously with the upper Hell Creek Formation, the anagenesis hypothesis predicts that only T. prorsus should occur within the Frenchman Formation.I tested this hypothesis against two alternatives with reference to the available Triceratops skull material from the Frenchman Formation, which had not been systematically studied prior to our investigation.Using qualitative comparisons and linear discriminant analyses, I found that nasal horn cores were generally larger, accompanied by a wide, vertically oriented, nasal process of the premaxilla, traits previously associated with the geologically younger T. prorsus.Hierarchal cluster analyses, revealed no distinct groupings of T. prorsus, implying a homogenous population.Thus, I concluded that all Triceratops material from the Frenchman Formation compare most closely to T. prorsus.and therefore find support for the original anagenesis hypothesis.Additionally, I was able to relocated and provide stratigraphic data for six Triceratops specimens from the Frenchman Formation.I found no preference in depositional environment, with specimens equally distributed in both sand and mudstone facies.When relatively dated against each other, I found no fine scale trends in morphology had occurred across the latest Maastrichtian, suggesting that Triceratops may have been in evolutionary stasis prior to its extinction at the end of the Cretaceous.
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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 | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".