Morphometric analysis of the gull Larus (Aves:Laridae) with implications for small theropod diversity in the Late Cretaceous
Bibliographic record
Abstract
This project analyzed morphological diversity in the modern gull (Aves: Charadriiformes) genus Larus.Measurements of the post-cranial skeletons were made on specimens from six species of Larus and analyzed using Principal Component Analysis (PCA).Similar analyses were conducted on a series of theropod taxa.Landmark-based geometric morphometric analysis was also conducted on select skulls of gulls and analyzed using PCA.The results show that most of the gull species are very similar for the morphological parameters analyzed, only differing in overall body size, and, thus cannot be easily distinguished based on their skeletal morphology.These results were used as a modern analogue for inferring species diversity in the theropod fossil record.The implications of this study suggest that skeletal morphology, without the addition of soft tissue and behavior data available for modern birds, may not be able to distinguish closely related species of interbreeding, non-avian theropods in the fossil record.This suggests that the species diversity of extinct non-avian theropods was likely higher than can be of determined from their skeletal remains.
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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 | 0.000 | 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 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".