New data on the diversity and abundance of small-bodied ornithopods (Dinosauria, Ornithischia) from the Belly River Group (Campanian) of Alberta
Bibliographic record
Abstract
Relative to large-bodied dinosaurs, the diversity of small-bodied dinosaurs from the Campanian of North America is poorly understood due to a lack of well-preserved skeletons. We document the first articulated remains, as well as the first cranial bones, of non-iguanodontian ornithopods from the Belly River Group of Alberta. The geologically oldest specimen consists of the posterior half of an articulated skeleton from the middle unit of the Oldman Formation and shares many anatomical features with the contemporaneous Orodromeus makelai and the older Oryctodromeus cubicularis. A second, younger specimen from the upper Oldman Formation is distinct from other ornithopods in having a reduced distal portion of the fibula that is fused to the anterior surface of the tibia; it is designated as the type of a new taxon, Albertadromeus syntarsus, gen. et sp. nov. Numerous isolated elements from small ornithopods from the Dinosaur Park Formation are also identified, but cannot be assigned to the generic level with confidence. Although small-bodied ornithopod material is rare, their known postcranial material outnumbers those of taphonomically equivalent and contemporaneous pachycephalosaurs, which are known to be abundant and diverse due to their robust and frequently recovered cranial domes. These findings suggest considerable undiscovered diversity of small-bodied ornithopods, and highlight biases against the preservation of small taxa in this system. SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP
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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 | 0.003 | 0.003 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".