Re-appearance of hypercarnivore ichthyosaurs in the Cretaceous with differentiated dentition: revision of ‘<i>Platypterygius</i>’ <i>sachicarum</i> (Reptilia: Ichthyosauria, Ophthalmosauridae) from Colombia
Bibliographic record
Abstract
Early Cretaceous ichthyosaur diversity has markedly increased in recent years with the discovery of new taxa in the field and in museum collections. This has led to new characters, and a better understanding of taxonomically informative anatomy. Here, we re-describe the holotype of the ophthalmosaurid Platypterygius sachicarum from the Barremian–Aptian of Colombia and place these data in a phylogenetic context. The validity of the species is supported by several new characters of the narial region, mandible and dentition. The dentition is unique among ichthyosaurs in that it presents several discrete tooth morphologies that range from piercing to cutting to crushing. In combination, these cranial specializations imply a large vertebrate diet and make this taxon the first Cretaceous hypercarnivorous ichthyosaur. Differences from the type species of Platypterygius, P. platydactylus, include a suite of characters associated with differing feeding ecologies and the complex external nares. The large number of character differences and revised phylogenetic relationships are used to remove the Colombian taxon from Platypterygius and recognize it as a new genus, Kyhytysuka sachicarum comb. nov. A revised set of taxonomic definitions are proposed for Ophthalmosauria to maintain stability at this important node. Kyhytysuka sachicarum opens new questions regarding the diversity and paleobiogeography of Early Cretaceous ichthyosaurs from northern Gondwana and highlights the importance of individually assessing each ‘Platypterygius’ species and, potentially, specimen to better understand the diversity of this broadly distributed taxon.http://zoobank.org/urn:lsid:zoobank.org:pub:E3FD55AF-2AD1-46CA-A49C-1FB4B102AB2C
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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 | 0.002 | 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) | 0.002 | 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".