Morphology and osteohistology of a large‐bodied caenagnathid (Theropoda, Oviraptorosauria) from the Hell Creek Formation (Montana): implications for size‐based classifications and growth reconstruction in theropods
Bibliographic record
Abstract
Abstract Oviraptorosaurs, like many coelurosaurians, are frequently diagnosed using incomplete or fragmentary skeletal remains, with factors such as body size often used to assign material to a particular taxon or as a basis for describing new species. Here we describe a partial skeleton, ROM VP 65884, from the Hell Creek Formation (Montana, USA ), and through morphological and phylogenetic comparisons identify it as belonging to Caenagnathidae, and probably referable to Anzu wyliei . We perform multi‐element osteohistological sampling of the tibia, fibula, manual phalanx, rib and gastralium of ROM VP 65884 to determine the ontogenetic status of the individual, and to perform a detailed assessment of the intra‐skeletal variation present in a series of histological proxies for growth and development. Skeletochronological analysis suggests ROM VP 65884 was still actively growing at time of death. Lacunar area was variable, but consistent with values reported for other dinosaurs and vertebrates. Osteocyte lacunar density was found to be relatively similar to the few previous measurements known from coelurosaurian dinosaurs, and preserved no ontogenetic pattern. Osteocyte lacunar density ( OLD ) was much higher in sampled rib and gastralia elements when compared to limbs, and the high variability in OLD overall lends further support against the hypothesis of this feature acting as a proxy for mass‐specific growth rate. Our results stress the importance of using osteohistological analyses to constrain variation and permit ontogenetic assessment, and suggest caution be taken when using size as a determinant for referral of disassociated elements to specific or new coelurosaur taxa.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".