Comparison of embryonic development, from <scp>HH21</scp> to <scp>HH40</scp>, between ostrich (<i>Struthio camelus</i>) and chicken (<i>Gallus gallus</i>)
Bibliographic record
Abstract
BACKGROUND: The chicken has been a representative model organism to study embryonic development in birds, however important differences exist among this class of species. As a representative of one of oldest existing clades of birds, the African ostrich (Struthio camelus), has the largest body among birds, and has two toes. Our purpose is to establish the corresponding stages in ostrich embryo development that match the well-established HH system of the chicken to facilitate comparative studies between the ostrich and other birds to better understand differences in development. RESULTS: Here we describe in detail the middle period of embryonic development using microscopic images and skeletal staining. We found that clear morphological differentiation between the ostrich and the chicken begins at stage 26. Bird limb cartilage first form in stage 25, while the development of the limb skeletons differs after stage 31. Calcification of limb skeletons in the chicken was completed faster. The first and second toes of the ostrich disappear at stages 36 and 38, respectively. CONCLUSIONS: This study should greatly aid ostrich-related developmental and morphological research and provide a reference for studying the development and evolution of avian limb skeletons, including molecular research. Questions that can now be addressed include studies into the fusion of tarsometatarsal skeleton, ossification, and digit loss.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 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".