Comparative ossification and development of the skull in palaeognathous birds (Aves: Palaeognathae)
Bibliographic record
Abstract
Ratites and tinamous are a morphologically diverse group of flightless and weakly flighted birds. As one of the most basal clades of extant birds, they are frequently used as an outgroup for studies discussing character evolution within other avian orders. Their skeletal development is not well known in spite of their important phylogenetic position, and studies have historically been plagued with small sample sizes and limited anatomical and temporal scope. Here, I describe the ossification of the skull in the emu (Dromaius novaehollandiae), ostrich (Struthio camelus), greater rhea (Rhea americana), and elegant crested-tinamou (Eudromia elegans). Skeletal development is remarkably consistent within palaeognaths, in spite of large differences in absolute size and incubation period. Adult morphology appears to play a role in interordinal differences in the sequence and timing of ossification of certain bones. Neither the timing of cranial ossification events relative to stage nor the sequence of ossification events provides any evidence in support of a paedomorphic origin of the palaeognathous palate. This study provides an important first look at the timing and sequence of skull development in palaeognathous birds, providing data that can be compared to better-studied avian systems in order to polarize ontogenetic characters.
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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".