Redescription of UALVP 40, an unusual specimen of <i>Chasmosaurus</i> Lambe, 1914 (Ceratopsidae: Chasmosaurinae) bearing long postorbital horns, and its implications for ontogeny and alpha taxonomy of the genus
Bibliographic record
Abstract
UALVP 40, an articulated and reasonably complete skull of a small chasmosaurine dinosaur collected in 1920 by George F. Sternberg from the lower unit of the Dinosaur Park Formation, Dinosaur Provincial Park, Alberta, Canada, is here redescribed. The focus of the study is on the newly prepared right side of the skull and the hitherto undescribed mandible. There are substantial differences between the right and the left side of the skull, most notably the right postorbital horncore exhibits a greater angle of inclination at 60° from horizontal, which is approximately 15° greater than that of the left. The right side of the skull also shows many unfused cranial sutures that are obliterated on the left side. These unfused sutures and the short predentary lacking an anterior elongation, indicate that UALVP 40 likely represents a subadult individual. UALVP 40 is diagnosed to the genus Chasmosaurus by its possession of the following: (i) premaxillary flange along entire anterior margin of external naris; (ii) supraorbital horns curving posteriorly along their length; and (iii) squamosal dorsal border laterally adjacent to supratemporal fenestra straight in profile, sloping posteroventrally at a shallow angle before ascending farther posteriorly to form lateral border of parietal fenestra. The last character is newly proposed. A bivariate correlation in UALVP 40 and other Canadian specimens of Chasmosaurus bearing long postorbital horncores (>150 mm long) reveals a near isometric relationship between interorbital width and horn length. This may indicate those specimens represent an ontogenetic series of a single species diagnosed by long postorbital horncores.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.003 |
| 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".