The heterodonty of<i>Albertosaurus sarcophagus</i>and<i>Tyrannosaurus rex</i>: biomechanical implications inferred through 3-D modelsThis article is one of a series of papers published in this Special Issue on the theme<i>Albertosaurus</i>.
Bibliographic record
Abstract
The objective of this study is to analyze how different crown morphologies and different root lengths respond to stresses generated by the bite forces of Albertosaurus sarcophagus and Tyrannosaurus rex . Six well-preserved teeth of A. sarcophagus from the Albertosaurus bonebed in Dry Island Park (southern Alberta) were selected to study their biomechanics, and T. rex teeth were included for comparison. The three-dimensional (3-D) models were obtained through computerized tomography (CT) scanning and 3-D digitizing. Finite element analyses were performed in Strand7®. Bite forces for Albertosaurus and Tyrannosaurus were calculated based on cranial and jaw proportions. The results were viewed with the Tresca yield criterion. The ratios of shear stresses observed along the mesio-distal versus labio-lingual axes of all models allows the identification of similar stress distribution patterns in the upper and lower jaws of Albertosaurus and the upper jaws of Tyrannosaurus, with a higher amount of shear along the mesio-distal axis occurring in the mid-maxillary teeth. The dentary teeth of Tyrannosaurus, however, show a different stress distribution pattern, with a higher amount of shear occurring along the labio-lingual axis of the mid-dentary teeth. These differences in jaw mechanics suggest that the function of teeth in the lower jaw of Tyrannosaurus shifted a few positions to compensate different proportions in the dentary that cause the anterior dentary teeth to be aligned with the largest maxillary teeth in Tyrannosaurus. These results suggest that heterodonty in these groups is different and that tooth form and function are sensitive to jaw proportions.
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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 | 0.001 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".