The skeletal morphology and phylogenetic position of Adocus amtgai, an adocid turtle from the Late Cretaceous of Mongolia

The first ‘true’Adocus(Testudines, Adocidae) from the Paleogene of Asia

“…In addition to the new species described below, our study relies on published data and personal observations on the following adocid taxa: Adocus agilis Cope, 1868a, from the Upper Cretaceous of the U.S.A. (AMNH 1466;Hay, 1908); Adocus aksary Nessov in Nessov and Krasovskaya, 1984, from the Upper Cretaceous of Uzbekistan (see Syromyatnikova and Danilov, 2009); Adocus amtgai Narmandakh, 1985, from the Upper Cretaceous of Mongolia (PIN 3640-2, 3640-3; Syromyatnikova et al, 2011;unpubl. data); Adocus annexus Hay, 1910, from the Paleocene of the U.S.A. (Hay, 1910;Gilmore, 1919); Adocus beatus (Leidy, 1865) from the Upper Cretaceous of the U.S.A. (AMNH 1138(AMNH , 1350YPM 782;Hay, 1908;White, 1972;I.G.D., pers.…”

“…According to modern phylogenetic studies Syromyatnikova, 2009a, 2009b;Syromyatnikova, 2011;Syromyatnikova et al, 2012), Adocidae includes Yehguia tatsuensis (Ye, 1963) from the Upper Jurassic of China, which is the sister taxon to a clade uniting all other adocids, consisting of Adocus Cope, 1868a (Adocinae Cope, 1870; Cretaceous-early Oligocene of Asia; Late Cretaceous-Paleocene of North America), and a clade uniting the genera Ferganemys Nessov and Khosatzky, 1977a, and Shachemys Kuznetsov, 1976(Shachemydinae Khosatzky in Nessov and Khosatzky, 1977b; Cretaceous of Asia). The genus Adocus is diagnosed by overlapping of the marginals onto the costals in the middle and posterior parts of the carapace (synapomorphy of Adocus), whereas other adocids either have overlapping of the marginals onto the costals only in the middle part of the carapace (Yehguia tatsuensis) or have no such overlapping, i.e., the marginals are restricted to the peripherals (Ferganemys spp., Shachemys spp.).…”

Turtle shell bone and osteoderm histology of Mesozoic and Cenozoic stem-trionychian Adocidae and Nanhsiungchelyidae (Cryptodira: Adocusia) from Central Asia, Mongolia, and North America

“…The samples have been chosen to cover as much of the taxonomic breadth of both groups as possible. Preliminary histological results of the adocid and nanhsiungchelyid shell bones from North America have already been reported in Scheyer (2007) and Scheyer and Anquetin (2008), and those from Asia and North America by Syromyatnikova et al (2016).…”

“…Of those, Adocus is the only taxon encountered in both Asia and North America (Danilov et al, 2011). The skeletal morphology of Adocus has been extensively described (Meylan and Gaffney, 1989), whereas a revision of the genus Adocus from the Late Cretaceous of Asia was given more recently (Syromyatnikova andDanilov, 2009, 2013;Syromyatnikova et al, 2012. In addition, the first truly identifiable Adocus material from the Palaeogene of Asia was described, together with a comparison of surface sculpture patterns in the genus, as Adocus inexpectatus (Danilov et al, 2013b.…”

“…According to Danilov and Syromyatnikova (2009a, b), Adocidae includes Yehguia tatsuensis (Yeh, 1963) (current name Sinaspideretes wimani Young and Chow, 1953, sometimes excluded from Adocidae; see Tong et al, 2014;Joyce et al, 2016) and two clades: Adocinae Cope, 1870, with a single genus, Adocus Cope, 1868 ( = Adocoides Sukhanov and Narmandakh, 2006;= Shineusemys Sukhanov and Narmandakh, 2006; see Syromyatnikova et al, 2012, and Shachemydinae Khosatzky in Nessov and Khosatzky (1977), with the genera Shachemys Kuznetsov, 1976and Ferganemys Nessov and Khosatzky, 1977(see Syromyatnikova, 2011. Of those, Adocus is the only taxon encountered in both Asia and North America (Danilov et al, 2011).…”