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Nichollsemys
Taxonomy
Nichollsemys was named by Brinkman et al. (2006). It is not extant.
It was assigned to Chelonioidea by Brinkman et al. (2006); and to Chelonioidea by Menon et al. (2024).
It was assigned to Chelonioidea by Brinkman et al. (2006); and to Chelonioidea by Menon et al. (2024).
Species
Synonymy list
| Year | Name and author |
|---|---|
| 2006 | Nichollsemys Brinkman et al. |
| 2024 | Nichollsemys Menon et al. |
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If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.
Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| D. Brinkman et al. 2006 | A primitive non-protostegid chel- onioid similar to Toxochelysin that: a secondary palate is absent, the foramen palatinum posterius is large, the triturating surfaces are narrow but different from Toxochelys in the reduced exposure of the basisphenoid on the ventral surface of the palate, the presence of a mid-ventral ridge on the palate extending between the basisphenoid and vomer, the foramen anterior canalis carotici interni is separated by a thin bar of bone, the canalis caroticus internus joins the sulcus cavernosus, and the foramen caroticum laterale is larger than the foramen anterior canalis carotici intemi. Nichollsemys differs from Ctenochelys in the presence of relatively narrower triturating surfaces that do not include the vomer and a larger foramen palatinum posterius. Nichollsemys differs also from Porthochelys in exhibiting a relatively narrower skull that is more triangular-shaped in dorsal view and in the small exposure of the basisphenoid on the ventral surface of the palate. | |
| J. C. L. Menon et al. 2024 | Nichollsemys baieri can be identified as belonging to
Pan-Chelonioidea by having a roughly triangular ventral exposure of the parabasisphenoid, with both ventral pterygoid ridges forming a reverse “V” pattern alongside the parabasisphenoid and basioccipital ventral exposures; a posteriorly retracted processus inferior parietalis (Gaffney, 1979); a high dorsum sellae with a distinct dorsomedian process between both clinoid processes. |