Computed tomography and three-dimensional reconstruction of the skull of the stem tetrapod <i>Crassigyrinus scoticus</i> Watson, 1929
Bibliographic record
Abstract
The early tetrapod Crassigyrinus scoticus was a large aquatic predator known from the lower- to mid-Carboniferous (upper Tournasian to upper Visean/lower Serpukovian, approximately 350–330 Ma) of Scotland and Canada. Crassigyrinus is enigmatic in terms of its phylogenetic position due to its unusual morphology, which features a mixture of primitive and derived characters. Previous reconstructions, based on five incomplete and deformed specimens, have suggested a dorsoventrally tall skull with a short and broad snout, large orbits and external nares, and an extended postorbital region. In this study, we scanned four specimens using computed tomography and segmented imaging data to separate bone from matrix and individual bones from each other. Based on these data, we present a revised description of the upper and lower jaws, including sutural morphology and abundant new anatomical information. Damage was repaired and the skull retrodeformed to create a hypothetical three-dimensional reconstruction of the skull of Crassigyrinus that is dorsoventrally flatter than earlier reconstructions, yet still morphologically unique amongst early tetrapods. Overall skull shape, the size and distribution of the teeth, sutural morphology, and the specialized anatomy of the jaw joint and mandibular symphysis all suggest that Crassigyrinus was a powerful aquatic predator capable of hunting and subduing large prey.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.001 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 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".