Osteological and taxonomic reassessments of <i>Sahaliyania elunchunorum</i> (Dinosauria, Hadrosauridae) from the Upper Cretaceous Yuliangzi Formation, northeast China
Bibliographic record
Abstract
The osteology and taxonomy of the lambeosaurine Sahaliyania elunchunorum from the upper Yuliangzi Formation (middle Maastrichtian) are reevaluated herein. Based on detailed morphological comparisons among hadrosauroids, we argue that Wulaga lambeosaurine specimens, most of which were previously ascribed to S. elunchunorum, display a combination of features that is typical of Amurosaurus riabinini from the upper Udurchukan Formation (middle Maastrichtian) at the Blagoveschensk locality. This combination includes several anterodorsally-posteroventrally oriented lateral foramina of the maxilla with a very large last one partially obscured by the ventral extremity of the jugal contact, a narrow infratemporal region of the jugal that is ∼70% as wide as the orbit, a relatively low anterior third of the strongly dorsally concave sagittal crest of the parietal, mesiodistally wide maxillary tooth crowns (∼1.2–1.3 teeth per cm), the sternal posterolateral process slightly shorter than the anteromedial plate, and a gently ventrally deflected preacetabular process of the ilium. Considering the osteological similarities and the fact that the Yuliangzi and Udurchukan formations were deposited synchronously in the same basin, S. elunchunorum is regarded here as a junior synonym of A. riabinini. Approximately 70% of the complete Amurosaurus fibulae from the Wulaga bonebed exhibit a total length of more than 85 cm that probably corresponds to the adult stages. Histological sections from these fibulae are moderately remodeled by dense secondary osteons, with poorly developed vascularization of primary osteons along fibrolamellar bone in the outer cortex. The phylogenetic analysis of Lambeosaurinae recovers a sister-taxon relationship between Amurosaurus and Lambeosaurus.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 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) | 0.001 | 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 teacher head, 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".