Ancestral body plan and adaptive radiation of sauropterygian marine reptiles
Bibliographic record
Abstract
Sauropterygia is the most diversified and dominant clade among marine reptiles, but their early evolution is scarcely understood. Here we report the earliest known complete specimen related to sauropterygians from the Early Triassic. It is referred to Hanosaurus hupehensis by an exclusive combination of features and shows mosaic morphology integrating the characters of multiple sauropterygian sub-lineages. In phylogenetic results from both parsimony and Bayesian analyses employing our reconstructed dataset, Hanosaurus is stably resolved as the basal-most member of Sauropterygiformes, a clade comprising all sauropterygians and saurosphargids. This skeleton reveals an unexpected ancestral body plan for sauropterygiforms with an elongate trunk and four short limbs, differing from many of its immediate descendants but more similar to non-sauropterygiform marine reptiles at their early aquatic stage as axial swimmers. After this convergence on body plan, we quantitatively confirm the rapid divergence of sauropterygiform reptiles following the end-Permian mass extinction.
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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 | 0.000 |
| 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".