Allometric growth and intraspecific variation of the craniomandibular bones of <i>Tarbosaurus bataar</i> (Theropoda, Tyrannosauridae): a geometric morphometric approach
Bibliographic record
Abstract
Since it was first described in 1955, many fossils of the tyrannosaurid theropod Tarbosaurus bataar have been recovered from the Upper Cretaceous Nemegt Formation of Mongolia and its contemporaneous units in east Asia. Among these, there were individuals of different sizes and stages of maturity, but not much research has been done on the changes that occurred during the growth of this dinosaur. In this work, growth trajectories in the shape of various, individual craniomandibular bones of Tarbosaurus bataar are examined through geometric morphometrics. Several major changes in craniofacial anatomy are observed through the growth series, including increases of the relative heights of the dentary, jugal, maxilla, and nasal; the transition of the lacrimal from a T-shape to a 7-shape; negative allometric growth in the anteroposterior length of the orbit; increased sizes of the cornual processes of the postorbital and the ventral flange of the jugal; broadening of the frontal accompanied by an enlargement of the dorsotemporal fossa; and widening and thickening of the nuchal crest so that the midlength of the parietal appears relatively narrower. Such results indicate the main allometric shape change patterns in craniomandibular anatomy of Tarbosaurus bataar were broadly congruent with those of other tyrannosaurids, particularly with Tyrannosaurus rex. It is assumed that many of these changes were related to disproportionate increase of the bite forces and strengthening the skull structure during growth. Additionally, a significant amount of variation appears to be uncorrelated with size, suggesting that Tarbosaurus bataar, like other theropod dinosaurs, had significant intraspecific variation in craniomandibular anatomy.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.000 | 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) | 0.001 | 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".