Abstract
Abstract. Here we document the morphology of the only known skull of a carettochelyid turtle from North America. The specimen originates from the middle Eocene (early Uintan) Washakie Formation of Sweetwater County, Wyoming, and is referred to Anosteira pulchra based on temporal considerations. The skull of Anosteira pulchra broadly corresponds in its morphology to that of other carettochelyids but exhibits numerous differences that are related to it being more gracile. As a meaningful outgroup is lacking, it is not possible to determine if the gracile morphology seen in this taxon is apomorphic or plesiomorphic for the Anosteira–Allaeochelys clade. Anosteira pulchra and Carettochelys insculpta lack an ossified palatine canal. We conclude by reference to extant trionychids that the palatine (mandibular) canal is likely present but branches from the cerebral (pseudopalatine) canal following its exit from the sella turcica. As in trionychids, the vidian branch of the facial nerve (VII) of Anosteira pulchra and Carettochelys insculpta mostly traverses the palatine.
Highlights
The pig-nosed turtle Carettochelys insculpta Ramsay, 1887 from New Guinea and Australia is the only surviving representative of the clade Carettochelyidae (Pan-Carettochelys of Joyce et al, 2004)
Given that Field Museum of Natural History (FMNH) PR966 is the only known pan-carettochelyid skull from North America, the primary purpose of this contribution is to provide a description of this fossil
The slice stack is available upon request at FMNH
Summary
The pig-nosed turtle Carettochelys insculpta Ramsay, 1887 from New Guinea and Australia is the only surviving representative of the clade Carettochelyidae (Pan-Carettochelys of Joyce et al, 2004). Fragmentary remains document the early evolution of this clade during the Cretaceous in Asia, but sometimes exceptionally rich material attests to the spreading of carettochelyids to all northern continents during the Paleogene. The Neogene record is restricted to exceptionally rare finds from Europe, northern Africa, south Asia, and Australia (Joyce, 2014). 173) provided a reconstruction of this fossil (FMNH PR966) under the name “Anosteira” or “Pseudanosteira”, whereas Havlik et al (2014) used it to score all cranial aspects of the taxon “Anosteira pulchra”, but a formal description is still missing. Given that FMNH PR966 is the only known pan-carettochelyid skull from North America, the primary purpose of this contribution is to provide a description of this fossil
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