Taking a crack at the dome: histopathology of a pachycephalosaurid (Dinosauria: Ornithischia) frontoparietal dome
Bibliographic record
Abstract
Recent studies have identified numerous pathologies in the cranial domes of pachycephalosaurid dinosaurs. These studies utilized CT images of domes to identify secondary woven bone and sclerosis associated with the pathologies. These features were critical for diagnosing post-traumatic osteomyelitis, which supported the head-butting behaviour hypothesis. However, conventional CT image resolution may not be sufficient to identify secondary woven bone or sclerotic bone in fossil specimens. UALVP 8504 (cf. Foraminacephale brevis), a dome possessing putative bone lesions, was thin-sectioned and micro-CT scanned. Thin sections revealed the lesions are lytic, without any secondary woven bone or sclerosis, falsifying the diagnosis of osteomyelitis. The morphology and histology of the lesions of UALVP 8504 are not diagnostic and resemble both post-traumatic and non-traumatic lesions. However, UALVP 8504 possesses shifted vascular canals (repositioning via remodeling, which maintains anatomical position throughout ontogeny) that are decoupled from growth (), and drifting osteons (secondary osteons where resorption occurs longitudinally and transversely). These demonstrate that the dome has sustained external mechanical loading, likely resulting from an impact or multiple impacts, consistent with the head-butting hypothesis. These impacts may have damaged overlying soft tissues and formed the lesions along the surface. Therefore, we suspect that the pathologies in UALVP 8504 are post-traumatic.
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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 | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 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".