Description and revised diagnosis of Asia’s first recorded pachycephalosaurid, <i>Sinocephale bexelli</i> gen. nov., from the Upper Cretaceous of Inner Mongolia, China
Bibliographic record
Abstract
The first recorded pachycephalosaurid dinosaur from outside of North America, “Troodon” bexelli, was described from the Upper Cretaceous of Nei Mongol (Inner Mongolia) Autonomous Region, China, in 1953 based on a partial parietal dome. The holotype, and only, specimen has not been redescribed or figured since the original description and is currently considered lost. As a result, researchers have generally considered this taxon a nomen dubium. Here, we identify and describe two high-fidelity plaster casts of the holotype and assign them as plastotypes for this taxon. Examining these replicas allows for an updated comparative description and complete systematic revision of this enigmatic taxon and its inclusion within a phylogenetic analysis for the first time. The material is distinct from all other pachycephalosaur material and can be diagnosed by a single autapomorphy (a wide and deeply embayed posterior parietal margin) and a unique combination of characters, including lack of primary nodes on the parietal and a highly arched, fully roofed temporal chamber. A new genus, Sinocephale gen. nov. is established to receive this species as Sinocephale bexelli. Sinocephale bexelli is phylogenetically removed from Stegoceras (formerly “Troodon”), to which it was previously affiliated, and recovered as a pachycephalosaurine pachycephalosaurid.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".