Boulenger, 1887
Pig-nose turtles
Recognition
Carettochelyids are known from the Eocene of North America, Europe and Pakistan, and the fossil species Kizylkumemys schultzi is from the late Cretaceous of Uzbekistan (Nessov, 1987). This formerly widespread family is today represented by only one living species, Carettochelys insculpta, the pig-nose turtle, restricted to New Guinea and northern Australia. At present the family is composed of two subfamilies: the Anosteirinae, which includes the fossil genera Anosteira, Pseudanosteira, and Kizylkumemys; and the Carettochelyinae, which includes the living genus Carettochelys and the fossil genera Allaeochelys and Chorlakkichelys (Williams, 1950a; Meylan, 1988a). Anosteirines are small and have a very long, narrow xiphiplastra, one or more well-developed spines in the neural bone series, carapacial scutes, with vertebral 2 bounded laterally by the first vertebral and vertebral 1 partly or completely longitudinally divided. Carettochelyines are larger and have shorter, broader xiphiplastra, neural spines usually absent, and scutes absent from both the plastron and carapace.
The karyotype, protein electrophoretics, and morphology of the living Carettochelys insculpta indicate that it is most closely related to the softshelled turtles, the family Trionychidae (Frair, 1985; Bickham et al., 1983; Bickham and Carr, 1983; Gaffney and Meylan, 1988a). A similar conclusion was drawn by Shaffer et al. (1997), who generated clades based on a combination of morphological and molecular characters.