The dinosaurs of the Early Jurassic Hanson Formation of the Central Transantarctic Mountains: phylogenetic review and synthesis
Bibliographic record
Abstract
The Hanson Formation of the Central Transantarctic Mountains has yielded a diverse Early Jurassic terrestrial fauna, which includes the nearly complete theropod dinosaur, Cryolophosaurus ellioti, and a fragmentary basal sauropodomorph dinosaur.The Hanson Formation dinosaurs are important for understanding early dinosaur evolution because: 1) they preserve a mosaic of morphological traits that render them useful for interpreting poorly known parts of the dinosaur evolutionary tree; 2) they are from the Early Jurassic, a critical period in early dinosaur evolution about which knowledge is scant; and 3) they are the only known Early Jurassic dinosaurs from Antarctica, making them particularly valuable for understanding patterns of biotic interchange during this time.Recent research suggests that Cryolophosaurus belongs to a geographically widespread clade of mid-sized, Early Jurassic theropods with cranial crests that includes Dilophosaurus wetherilli, 'Dilophosaurus' sinensis, and Dracovenator, and renders Coelophysoidea sensu lato non-monophyletic.The Antarctic sauropodomorph represents a distinct taxon that is a member of a similarly diverse massospondylid clade.This taxon shares a number of features with more derived sauropodomorphs, and provides additional evidence for the paraphyly of Prosauropoda.The phylogenetic relationships of the Antarctic dinosaurs are also consistent with a pattern of worldwide faunal homogeneity between Early Jurassic continental biotas.Furthermore, these analyses support a "ladder-like" arrangement for basal theropod and basal sauropodomorph phylogeny, suggesting that these groups passed through "coelophysoid" and "prosauropod" stages of morphological organization early in their respective evolutionary histories.
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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 | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.002 | 0.001 |
| Bibliometrics | 0.009 | 0.013 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 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".