identifier	taxonID	type	CVterm	format	language	title	description	additionalInformationURL	UsageTerms	rights	Owner	contributor	creator	bibliographicCitation
7B1E1965F61CFF89D4E36BC6CD20F826.text	7B1E1965F61CFF89D4E36BC6CD20F826.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Trionychoidae	<div><p>Trionychoidae gen. et sp. indet.</p><p>(Fig. 2)</p><p>DESCRIPTION</p><p>The specimen (PRC 149) is an almost complete first right costal plate, lacking only the lateral tip and part of the medial margin, which is damaged (Fig. 2). The plate is roughly triangular and slightly convex dorsally. As preserved, it measures 110 mm in length, 160 mm in width and 8 mm in thickness. The outer surface is covered with clear ornament of pitted pattern, formed by a network of irregular ridges. In the anterior marginal area, the ridges tend to arrange in a parallel manner, perpendicular to the border of the plate. Although wider than long, the plate is relatively long with the length/ width radio about 65%. The sutural margin with the nuchal is partly preserved and those with the peripheral 1 and 2 are intact. The nuchal/costal 1 suture is oblique. The costal 1/ peripheral 1 suture and that of costal 1/peripheral 2 have the similar length. The contact with the peripheral 3 is not preserved, and it is not clear whether the costal 1/peripheral 4 contact is present because the relevant part of the plate is broken. Part of the medial margin of the plate is damaged, but the preserved sutural margin indicates that the neural 1 is apparently rectangular. The posterior border of the plate is slightly convex posteriorly.</p><p>The scute sulci, although thin, are clearly imprinted on the dorsal surface. The lateral sulcus of the vertebral 1 is divergent anteriorly, reaching about the mid-length of the peripheral 1; this indicates a trapezoidal shape for the vertebral 1 with the posterior margin shorter than the anterior one. The intervertebral sulcus between the vertebrals 1 and 2 is convex forward. The vertebral 2 is clearly narrower than the vertebral 1.</p><p>On the inner surface, the strong second thoracic rib is straight, with a stubby and rounded rib head and sharp anterior edge which extends through the whole width of the plate. The first thoracic rib is damaged, it is short.</p><p>COMPARISON AND DISCUSSION</p><p>Three major groups of turtles are known from the Late Jurassic to the Early Cretaceous in Asia: Xinjiangchelyidae, Macrobaenidae / Sinemydidae, and Trionychoidae (Sukhanov 2000; Danilov et al. 2017; Tong 2017). Trionychoidae are notable for presenting a sculptured shell surface, a feature allowing isolated plates to be identified (Danilov et al. 2011, 2013b; Tong et al. 2014; Vitek &amp; Joyce 2015; Georgalis &amp; Joyce 2017). The ornamentation in PRC 149 which consists of a network of raised irregular ridges forming a pitted pattern is typical of Trionychoidae (sensu Gaffney &amp; Meylan 1988); such a sculpture is absent in Xinjiangchelyidae and Macrobaenidae / Sinemydidae . Within Trionychoidae, the sculpture in PRC 149 is reminiscent of some basal members of the group such as Isanemys srisuki Tong, Buffetaut &amp; Suteethorn, 2006 from the Lower Cretaceous Sao Khua Formation of NE Thailand and Ferganemys spp. from the mid-Cretaceous of Kyrgyzstan and Uzbekistan (Tong et al. 2006; Syromyatnikova 2011).</p><p>Among Trionychoidae, the presence of the scute sulci on the carapace surface and the contact with the peripherals exclude PRC 149 from the Trionychidae and Carettochelyidae, and place it in a more basal position. The triangular shape of the costal 1 is similar to that of Adocidae such as Ferganemys spp., Isanemys srisuki, Protoshachemys rubra Tong, Buffetaut, Suteethorn, Suteethorn, Cuny, Cavin, Deesri, Martin, Wongko, Naksri &amp; Claude, 2019, Adocus spp. (Tong et al. 2006, 2009b, 2019a, b; Syromyatnikova &amp; Danilov 2009; Syromyatnikova 2011; Danilov et al. 2013b; Syromyatnikova et al. 2013), whereas in more primitive turtles such as the xinjiangchelyids Chengyuchelys spp., Xinjiangchelys spp., and Annemys spp., the costal 1 is shorter, with nearly parallel anterior and posterior borders (Ye 1986; Peng &amp; Brinkman 1993; Tong et al. 2012, 2015a; Rabi et al. 2014). It is noteworthy that some basal trionychoids, such as Siamochelys peninsularis Tong, Buffetaut &amp; Suteethorn, 2002 from the Jurassic of southern Thailand, Basilochelys macrobios Tong, Claude, Naksri, Suteethorn, Buffetaut, Khansubha, Wongko &amp; Yuangdetkla, 2009 from the Phu Kradung Formation (Khorat Plateau) and Sinaspideretes wimani Young &amp; Chow, 1953 from the Xiashaximiao Formation of the Sichuan Basin, China, have a short costal 1 similar to that of xinjiangchelyids (Tong et al. 2002, 2009a, 2014). This difference from more primitive turtles is also indicated by the costal 1 length/width radio in PRC 149 (65%) which is greater than that of xinjiangchelyids and macrobaenids (around 40% to 50%) and falls within the range of primitive Adocidae ( Isanemys srisuki (61%) and Ferganemys verzilini Nessov &amp; Khosatzky, 1977 (64%) (Tong et al. 2009b; Syromyatnikova 2011), whereas Siamochelys peninsularis (44%) and Basilochelys macrobios (38%) have a costal 1 length/width radio similar to that of xinjiangchelyids (Tong et al. 2002, 2009a). The relatively high costal 1 length/ width value in S. wimani (54%) is likely related to the narrow anterior part of the shell, the morphology of this plate with the parallel anterior and posterior margins is closer to the condition in xiniangchelyids than to trionychoids (Tong et al. 2014). Among Trionychoidae, nanhsiungchelyids also have a relatively long costal 1 and many of them reach a large size, but the ornamentation of the shell surface is more prominent than that of PRC 149 (Hirayama et al. 2001; Danilov et al. 2013a; Brinkman et al. 2015).</p><p>The non-marine Mesozoic deposits of Thailand are rich in basal trionychoid fossils. Several taxa have been reported from the Khorat Group (Late Jurassic – Early Cretaceous). These include the large Basilochelys macrobios from the upper part of the Phu Kradung Formation, the small Isanemys srisuki and Protoshachemys rubra from the Sao Khua Formation, and the medium-sized Shachemys sp. from the Khok Kruat Formation (Tong et al. 2005, 2006, 2009a, 2019a). Large trionychoid turtle remains have also been collected from the Sao Khua Formation and stratigraphically coeval beds in eastern Thailand, but they are too fragmentary to warrant precise systematic assignment. As mentioned above, on the basis of the shape and the length/width radio of the costal 1, PRC 149 is more derived than Basilochelys . In addition, the vertebral 1 in PRC 149 is trapezoidal in shape and wider than the vertebral 2, whereas in B. macrobios, the vertebral 1 is roughly as wide as the vertebral 2, with the lateral borders slightly convergent forward (Tong et al. 2009a, b). With a carapace length estimated as about 75 cm, PRC 149 may be close to a large trionychoid turtle yet to be named from the Sao Khua Formation.</p><p>AGE OF THE KUT ISLAND DEPOSITS</p><p>When Buffetaut &amp; Ingavat (1983) first reported vertebrate remains from Kut Island, they tentatively assigned the assemblage an Early Jurassic age, which was in accordance with the attribution of the fossil-bearing strata to the Phu Kradung Formation (at the time referred to the Lower Jurassic (Tansathien et al. 1979)). Based on the vertebrate fauna, notably shark assemblage, Cuny et al. (2010) correlated the vertebrate-bearing beds of Kut Island with the Sao Khua Formation of the Khorat Group. This conclusion is supported by the more recent study of spinosaurid dinosaur teeth (Buffetaut et al. 2019). The presence of a large trionychoid turtle provides further evidence about the stratigraphical correlation of Kut Island deposits. In the Khorat Group, the Phu Kradung Formation contains two distinct turtle assemblages. The assemblage from the lower part of the formation (Late Jurassic) consists of xinjiangchelyids ( Phunoichelys thirakhupti Tong, Naksri, Buffetaut, Suteethorn, Suteethorn, Deesri, Sila, Chanthasit &amp; Claude, 2015 and Kalasinemys prasarttongosothi Tong, Naksri, Buffetaut, Suteethorn, Suteethorn, Chanthasit &amp; Claude, 2015). The upper part of the formation, which has yielded the abundant large basal trionychoid Basilochelys macrobios and an yet undescribed macrobaenid, is likely Early Cretaceous in age (Tong et al. 2009a, b, 2018). Turtle assemblages from the Sao Khua (Barremian) and Khok Kruat (Aptian-Albian) formations are so far exclusively composed of Trionychoidae . Adocidae and Carettochelyidae are recorded from both formations (the adocids Isanemys srisuki and Protoshachemys rubra, the carettochelyid Kyzilkumemys sp., and a large undetermined trionychoid from the Sao Khua Formation; and the adocid Shachemys sp. and the carettochelyid Kyzilkumemyskhoratensis Tong, Suteethorn, Claude, Buffetaut &amp; Jintasakul, 2005 from the Khok Kruat Formation (Tong et al. 2005, 2006, 2009b). Large trionychoid turtle remains have also been recorded from the Pra Prong locality (Sa Kaeo Province, eastern Thailand) which is coeval with the Sao Khua Formation; but they are (so far) not recorded from the Khok Kruat Formation. As mentioned above, the costal 1 from Kut Island is excluded from Trionychidae and Carettochelyidae; and its morphology is more derived than that of Basilochelys macrobios from the Phu Kradung Formation. Our study of the turtle remains would therefore support the conclusions based on sharks and dinosaurs (Cuny et al. 2010; Buffetaut et al. 2019), viz. that the vertebrate-bearing beds of Kut Island are Early Cretaceous rather than Jurassic in age and can be correlated with the Sao Khua Formation of the Khorat Group.</p></div>	https://treatment.plazi.org/id/7B1E1965F61CFF89D4E36BC6CD20F826	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		Plazi	Tong, Haiyan;Naksri, Wilailuck;Buffetaut, Eric;Suteethorn, Suravech;Suteethorn, Varavudh;Deesri, Uthumporn;Claude, Julien	Tong, Haiyan, Naksri, Wilailuck, Buffetaut, Eric, Suteethorn, Suravech, Suteethorn, Varavudh, Deesri, Uthumporn, Claude, Julien (2021): Turtle remains from the Early Cretaceous of Kut Island, Gulf of Thailand. Comptes Rendus Palevol 20 (19): 345-349, DOI: 10.5852/cr-palevol2021v20a19, URL: https://doi.org/10.5852/cr-palevol2021v20a19
