A new Ginglymodi (Actinopterygii, Holostei) from the Late Jurassic–Early Cretaceous of Thailand, with comments on the early diversification of Lepisosteiformes in Southeast Asia

A new ginglymodian fish, <i>Khoratichthys gibbus</i>, gen. et sp. nov., is described based on the impression of a single articulated fish preserved on a sandstone slab from the Late Jurassic–Early Cretaceous Phu Kradung Formation, northeastern Thailand. <i>Khoratichthys gibbus</i> is characterized by a distinct humpbacked body with elongate posterior spines on the dorsal ridge scales; the cheek is completely covered by bone; it has few infraorbitals, the elongate anterior-most one shows a tiny contact with the orbit, and six suborbitals arranged in one row; the opercule is rectancular in shape; the preopercule is narrow and regularly curved; and the interopercule large. A cladistic analysis including the type species of 25 ginglymodian genera indicates that <i>Khoratichthys</i> is the basal-most Lepisosteiformes, in an unresolved position with <i>Neosemionotus</i> and <i>Lophionotus</i>. This taxon provides a new evidence of the high diversity of ginglymodian fishes in the Phu Kradung Formation. A high taxic diversity of ginglymodians in Middle Jurassic–Early Cretaceous of southern Asian (excluding India) freshwater environments is observed, indicating that this clade occupied a major position in freshwater fish assemblages. http://zoobank.org/urn:lsid:zoobank.org:pub:AE3056BF-0C4A-421F-B517-3A4BC777A3E1 SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP Citation for this article: Deesri, U., P. Jintasakul, and L. Cavin. 2016. A new Ginglymodi (Actinopterygii, Holostei) from the Late Jurassic–Early Cretaceous of Thailand, with comments on the early diversification of Lepisosteiformes in Southeast Asia. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2016.1225747.