New specimens of<i>Platecarpus planifrons</i>(Cope, 1874) (Squamata: Mosasauridae) and a revised taxonomy of the genus
Bibliographic record
Abstract
One of the most enigmatic species of North American mosasaur, Platecarpus planifrons (Upper Coniacian—Lower Santonian), is re-diagnosed based on reference to the holotype, a new and very well-preserved skull (UALVP 24240), and several other less complete specimens. P. planifrons, once considered a nomen vanum, is diagnosed by a number of characters: separation of prefrontal and postorbitofrontal on ventral surface of frontal; dorsal surface of frontal planar with no mid-sagittal keel; width of preorbital region of frontal greater than interorbital width; frontal with paired posteromedian flanges; anterodorsal border of quadrate with distinct notch; stapedial pit narrow and keyhole shaped. The unexpected preservation of paired septomaxillae and the presence of a clear and well-defined vomerpterygoid contact in UALVP 24240 are reported. These new osteological data for P. planifrons permit re-evaluation of the species composition of the genus. Arguments are presented for the synonymy of P. coryphaeus with P. ictericus, while retaining the latter as distinct from the generic type, P. tympaniticus. Platecarpus cf. P. somenensis is tentatively retained. Thus, four species of Platecarpus from the Western Interior Seaway of North America are recognized.
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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 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.005 | 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".