Cranial Anatomy of New Specimens of <i>Saurornitholestes langstoni</i> (Dinosauria, Theropoda, Dromaeosauridae) from the Dinosaur Park Formation (Campanian) of Alberta
Bibliographic record
Abstract
The holotype of the dromaeosaurid Saurornitholestes langstoni was described in 1978 on the basis of fewer than 30 associated cranial and postcranial bones of a single individual from Dinosaur Provincial Park. Four additional partial skeletons of Saurornitholestes were recovered from Campanian (Upper Cretaceous) beds of Alberta and Montana over the next 25 years, although reasonably complete skeletons remained elusive, and virtually nothing was known about the skull. The lack of truly diagnostic material has been problematic, and the relationships of Saurornitholestes to other dromaeosaurids have been difficult to resolve because of the incomplete knowledge of its anatomy. In 2014, an almost complete skeleton, including the skull, was collected less than a kilometer from where the holotype had been found. Although similar in body size to Velociraptor, the facial region of the skull is relatively shorter, taller, and wider. The nasals are pneumatic. The premaxillary teeth are distinctive, and teeth previously identified in the Dinosaur Park Formation as Zapsalis abradens can now be identified as the second premaxillary tooth of S. langstoni. Morphology and wear patterns suggest that these may have been specialized for preening feathers. Many traits define a Campanian North American clade, Saurornitholestinae, that is distinct from an Asian clade that includes Velociraptor (Velociraptorinae). This new information on the skull allows a more complete evaluation of its systematic position within the Dromaeosauridae and supports the suggestion of at least two major faunal interchanges between Asia and North America during the Cretaceous. Anat Rec, 303:691-715, 2020. © 2019 American Association for Anatomy.
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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 | 0.002 | 0.001 |
| 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) | 0.003 | 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".