A new scincomorph lizard from the Early Cretaceous of Puebla, Mexico
Bibliographic record
Abstract
A complete skeleton of a new scincomorph lizard from the Early Cretaceous deposits of Tepexi de Rodriguez is described. Tepexisaurus tepexiigen. et sp. nov. is the best preserved early scincomorph and the first known taxon that is morphologically primitive to scincoids and paramacellodid lizards. The presence of pointed ventral parietal downgrowths, the coronoid overlapped anteriorly and posteriorly by the dentary and surangular, a small medial flange on the retroarticular process, and weak zygosphene and zygantrum articulations suggest scincoid relationships, but the absence of ventral and dorsal osteoscutes place Tepexisaurus as sister-group of this taxon. It shares the presence of + 30 closely packed teeth with the poorly known Upper Jurassic genus Saurillus and Pseudosaurillus, but differences in the coronoid structure, Meckelian groove and jaw proportions indicate that both taxa are distinct. Similar to Tepexisaurus, the absence of osteoscutes in Saurillus, Pseudosaurillus and Saurillodon place these taxa in a more primitive position relative to other paramacellodids which should be included within Scincoidea. Thus, Paramacellodidae as previously defined is a paraphyletic assemblage. The late presence of a pre-scincoid lizard in the Albian deposits of Tlayua can be correlated with the presence of sphenodontians and the relictual nature of the basal squamate Huehuecuetzpalli mixtecus. It gives additional evidence to support the hypothesis that Tlayua was a refuge for terrestrial archaic forms during the Albian.
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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 | 0.002 | 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) | 0.004 | 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".