Pedal and Manual Proximal Phalangeal Curvatures Among <scp> <i>Pongo abelii</i> </scp> and <scp> <i>Pongo pygmaeus</i> </scp>
Bibliographic record
Abstract
OBJECTIVES: Phalangeal curvature in hominoids correlates with locomotor behavior, with greater curvature associated with arboreality. Prior research using 2D geometric morphometrics (2DGM) demonstrated this relationship in the third manual proximal phalanges (mPP3) of orangutans. Specifically, the more terrestrial Bornean orangutans (Pongo pygmaeus) have less curved mPP3s than the less terrestrial Sumatran orangutans (Pongo abelii). This study extends the analysis to the third pedal proximal phalanges (pPP3) to assess if a similar pattern exists and further evaluate the link between curvature and locomotor diversity. METHODS: We analyzed pPP3 curvature in P. abelii (n = 16) and P. pygmaeus (n = 15) using a 2DGM approach. Comparisons were made with previously published mPP3 data. Generalized Procrustes analyses and principal components analysis were performed on 100 landmarks placed along the diaphysis's central longitudinal axis to quantify shape variation. ANOVA and post hoc tests determined significance between species and autopods. RESULTS: PC1 accounted for 73.4% of shape variance, primarily reflecting dorsoplantar curvature. P. abelii exhibited significantly greater curvature, aligning with its more arboreal lifestyle. Additionally, curvature in pPP3s was greater than in mPP3s within species. CONCLUSIONS: Results support the hypothesis that phalangeal curvature reflects habitual substrate use at lower taxonomic resolutions. The greater curvature in P. abelii corresponds to its predominantly arboreal locomotion, while the lesser curvature in P. pygmaeus aligns with increased terrestriality. Additionally, greater curvature in pedal versus manual phalanges may suggest differential adaptations related to substrate engagement. These findings enhance understanding of extant primate autopod functional morphology and can inform reconstructions of extinct species' positional behaviors.
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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 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".