Relative skull size as one of the factors limiting skull shape variation in passerines
Bibliographic record
Abstract
Despite a considerable interest among researchers in understanding the variation in skull shapes of birds and the factors influencing it, some of the drivers associated with the design features of an entire bird body, which are important for both successful terrestrial locomotion and flight, have been overlooked. One such factor, in our opinion, is relative skull size (skull length in relation to body mass), which can affect the position of the body’s center of gravity. We tested the effects of relative skull size, allometry (i.e., absolute skull size), and diet on variation in skull shape. The study was conducted on 50 songbird species representing a wide range of body masses (8.3–570 g) and dietary preferences (granivores, insectivores/granivores, insectivores, omnivores). Skull shape was analyzed using two-dimensional geometric morphometrics. We found that similar patterns of skull shape occur among passerines with different body sizes and diets. Relative skull size predicted skull shape to a similar extent and with a similar pattern as the absolute size. The effect of relative skull size on skull shape variation is likely due to biomechanical constraints related to flight.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".