Bibliographic record
Abstract
Reassessment of the anatomy of a three-dimensionally preserved, partial braincase from the Lower Cretaceous (lower Valanginian; ~139 mya) Kirkwood Formation of the Kirkwood Cliffs Quarry, South Africa, reveals it to be that of a new fossil snake species. The braincase presents a number of squamate skull features but also specific braincase features shared with early snakes such as Najash, Dinilysia, Sanajeh, and Menarana (e.g., presence of a large fenestra ovalis; fenestra rotunda separated from fenestra ovalis by prominent crista interfenestralis; reduced basal tubera on basioccipital). Phylogenetic relationships were analyzed using two distinct data sets and under different optimality criteria, recovering this new snake as an early-evolving lineage with close affinities to other Cretaceous Gondwanan snakes including Najash, Dinilysia, and other typical madtsoiids. This three-dimensionally preserved braincase reveals important aspects of early snake cranial evolution that were previously unknown from the oldest known fossil snakes. This specimen extends the fossil record of Gondwanan snakes by at least 45 my, making it the oldest known African and Gondwanan fossil snake and supporting a much broader palaeobiogeographical distribution of early snakes across ancient Gondwanan continents during the Early Cretaceous.
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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 | 0.001 | 0.011 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.002 |
| Bibliometrics | 0.005 | 0.006 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.003 | 0.002 |
| Open science | 0.002 | 0.003 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.109 | 0.074 |
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".