Chimerism in specimens referred to Saurophaganax maximus reveals a new species of Allosaurus (Dinosauria, Theropoda)
Bibliographic record
Abstract
Saurophaganax maximus is the designation of a massive theropod dinosaur recovered from the Kenton Member of the Upper Jurassic Morrison Formation in Oklahoma. The theropod was originally given the name Saurophagus maximus but was later revised to Saurophaganax maximus as the former did not conform to ICZN standards. Several autapomorphies were described for S. maximus including the postorbital lacking a postorbital boss, the atlas vertebra lacking facets for a proatlas, cervical vertebrae with nearly vertical postzygapophyses, unique accessory laminae on the holotype neural arch, pneumatized post-pectoral dorsal centra, laterally bowed femora, tibiae without an astragalar buttress and more prominent distomedial crest, less distally divergent fourth metatarsals, and craniocaudally expanded chevrons. However, our re-evaluation of these specimens shows that some of this material, including the holotype, is more parsimoniously referred to diplodocid sauropods found in the same quarry rather than an allosaurid. Because saurischian material referred to S. maximus is likely chimeric but diagnostic, we propose taxonomic revision and hypothesize dual validity. The name Saurophaganax maximus should refer to a previously undiagnosed diplodocid, instead of the large theropod recovered from the Kenton 1 Quarry. The presence of at least one skeletally mature theropod was confirmed through paleohistology of a fourth metatarsal. Despite the similarity of the theropod material to known species of Allosaurus, some decisively theropod specimens feature subtle autapomorphies that suggest a separate species, which we describe as Allosaurus anax sp. nov.
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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 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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".