Ontogenetic changes and sexual dimorphism in the cranium and mandible of the Atlantic walrus ( <i>Odobenus rosmarus rosmarus</i> L.)
Bibliographic record
Abstract
Walruses have been an important subsistence and cultural resource for humans and have been exploited for millennia across their distribution. This exploitation has contributed to severe declines in several populations and local extirpations. The study of walrus remains from archaeological sites can provide insights into past exploitation strategies and contribute to improving current conservation practices. The ability to differentiate disarticulated skeletal remains by age and sex can provide insights into past herd compositions. While sexing is a well-established approach for mandibles, a clear morphological key to determine such differentiation in crania is currently lacking. Here, linear measurements and geometric morphometrics of mandibles (n = 121) and crania (n = 116) of the Atlantic walrus (Odobenus rosmarus rosmarus) are used to describe the age and sex differences. Suture fusion states are strongly associated with age. There are clear size and shape differences between adults and neonates, with juveniles showing a gradual transition between states. Sexual dimorphism is clearly present in adults, but not detected in juveniles and neonates. Linear discriminant analysis successfully assigned sexes to 19 out of 21 (90.5%) DNA-sexed adult test specimens. Comparatively, only two out of five juvenile test specimens were correctly sexed using morphometrics. We suggest that aging specimens using suture fusion states, followed by classification between adult males and females, provides the most accurate results. This classification technique will facilitate future osteological studies on walruses, for example, to understand their ecomorphology and to provide insight into historical age- and sex-based exploitation and population impacts through time.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 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) | 0.000 | 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".