A review of pelvic shield morphology in ankylosaurs (Dinosauria: Ornithischia)
Bibliographic record
Abstract
The pelvic shield of ankylosaurian dinosaurs refers to an area of osteoderms lacking differentiated transverse bands over the pelvic region and it is used as a diagnostic character for various ankylosaur groups. The pelvic shield character varies across ankylosaur taxa but is typically coded as a binary character or is excluded from phylogenetic analyses, which obscures evolutionary trends and relationships. This study investigates for the first time pelvic shield morphology in a stratigraphic and geographic context. This paper comprehensively reviews pelvic shield morphology with firsthand observations of specimens, and proposes three categories of pelvic shield morphology. Category 1 pelvic shields have un-fused but tightly interlocking osteoderms. Category 2 pelvic shields have fused osteoderms forming rosettes and are restricted to the Late Jurassic to mid Cretaceous of North America and Europe. Category 3 pelvic shields have fused polygonal osteoderms of similar size, and are found in the mid- to Late Cretaceous of North America. Although the pelvic shield is used to characterize the Polacanthidae, an interpretation supported by this review, the validity of such a clade is dependent upon a global parsimony analysis incorporating this character. Future analyses of the Ankylosauria should incorporate a more detailed treatment of the pelvic shield to determine its diagnostic value within the group.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.004 | 0.005 |
| Science and technology studies | 0.000 | 0.000 |
| 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".