Permian gastropods from Thailand have been extensively studied over the last few years. The earliest known fossil collection was recovered in 1967 but has never been figured or described. Here, we document this historically important gastropod assemblage excavated from the upper-Lower to Middle Permian Ratburi Group of Khao Mang Lat in the Ban Kao District of Kanchanaburi Province, Central Thailand. The material comprises approximately 200 specimens, almost all of which represent a new species, Peruvispira kanchanaburiensis sp. nov. (Goniasmatidae), together with a single individual of Orthonychia sp. (Orthonychiidae = Platyceratidae). This exceptionally low-diversity community is unusual in comparison to Permian gastropod faunas reported from elsewhere, and could reflect either a low temperature palaeoenvironmental setting or priority effects resulting from early establishment of planktotrophic larvae within the local habitat. Baran Karapunar [karapunar@snsb.de], SNSB-Bayerische Staatssammlung für Paläontologie und Geologie, Richard-Wagner-Str. 10, 80333 München, Germany, and Department of Earth and Environmental Sciences, Paleontology & Geobiology, Ludwig-Maximilians-Universität München, Richard-Wagner-Str. 10, 80333 München, Germany; Alexander Nützel [nuetzel@snsb.de], SNSB-Bayerische Staatssammlung für Paläontologie und Geologie, Richard-Wagner-Str. 10, 80333 München, Germany, and Department of Earth and Environmental Sciences, Paleontology & Geobiology, Ludwig-Maximilians-Universität München, Richard-Wagner-Str. 10, 80333 München, Germany, and GeoBio-Center, Ludwig-Maximilians-Universität München, Richard-Wagner-Str. 10, 80333 München, Germany; Chatchalerm Ketwetsuriya [ketwetsuriya.c@gmail.com], Department of Earth Sciences, Faculty of Science, Kasetsart University, 10900 Bangkok, Thailand.

A new Permian gastropod assemblage from the Roadian (Middle Permian) Khao Khad Formation, Saraburi Group (Lopburi Province, Central Thailand) which is part of the Indochina Terrane, has yielded one of the most diverse Permian gastropod faunas known from Thailand. A total of 44 gastropod species belonging to 30 genera are described herein, including thirteen new species and one new genus. The new genus is Altotomaria. The new species are Bellerophon erawanensis, Biarmeaspira mazaevi, Apachella thailandensis, Gosseletina microstriata, Worthenia humiligrada, Altotomaria reticulata, Yunnania inflata, Trachydomia suwanneeae, Trachyspira eleganta, Heterosubulites longusapertura, Platyzona gradata, Trypanocochlea lopburiensis and Streptacis? khaokhadensis. Most of the species in the studied assemblage represent vetigastropods (35.6%) and caenogastropods (26.7%) and most of the species belong to Late Palaeozoic cosmopolitan genera. The studied faunas come from shallow water carbonates that are rich in fusulinids, followed by gastropods, ostracods, bivalves and brachiopods. The gastropod assemblage from the Khao Khad Formation shares no species with the gastropod assemblages from other Permian formations in Thailand, the Tak Fa Limestone and the Ratburi Limestone. However, it is similar to the Late Permian gastropod faunas from South China of the Palaeo-Tethys, therefore it suggests that the Indochina Terrane was not located far from South China.

Isolated theropod teeth are one of the most common vertebrate fossils that have been found in the Khorat Group of Thailand. Furthermore, several isolated teeth have been discovered from the Upper Jurassic Phu Kradung Formation, located in Phu Noi locality of Kalasin Province, Northeastern Thailand. Three of those theropod teeth from the Phu Noi locality show unique dental features that can be distinguished from previous discovered metriacanthosaurid theropod, including the lateral teeth with mesiolingual twisted mesial carinae extending above the cervix line and braided enamel surface texture. Morphological examination with cladistics and morphometric analyses show that these isolated teeth exhibit the synapomorphies of basal tyrannosauroids, closely related to Guanlong wucaii and Proceratosaurus bradleyi from the Jurassic Period. This paper notes the first report of a basal tyrannosauroid in Southeast Asia as well as significantly contributes to our understanding of paleoecology of the Upper Jurassic Phu Kradung Formation and paleobiogeography of Tyrannosauroidea during the Jurassic Period.

The Early Permian (Kungurian) Khao Khad Formation of Central Thailand consists mostly of carbonates deposited on the western margin of the Indochina Terrane. This formation has yielded unusual microbial-fusulinid limestones with large gastropods which contribute most to the rock volume. With a height of more than 6 cm, the gastropods are amongst the largest Early Permian gastropods ever reported. Gastropods as major rock formers are rare in the Palaeozoic. This, and other recently reported invertebrate faunas from Thailand show that gastropods may dominate Permian fossil assemblages not only in diversity, but also regarding abundance and in some cases also regarding biomass. Besides gastropods, fusulinids, various calcareous algae, intraclasts and thick microbial-cyanobacterial (Girvanella and Archaeolithoporella) coatings and reticular microbial patches as well as thick inter- and intragranular radial fibrous cement crusts are present. The gastropods represent at least four species and belong probably to undescribed taxa. The fusulinid genus Pseudofusulina and Misellina (M.) termieri are reported from the Khao Khad Formation for the first time and indicate a Bolorian age. Calcareous algae are dominated by dasycladaceans followed by gymnocodiaceans and solenoporaceans. The studied limestone almost completely lacks metazoan reef builders such as corals and sponges. Likewise, brachiopods and bivalves are absent in the studied samples and echinoderms are very scarce. The carbonate is interpreted as product of shallow water, back-reef lagoonal platform community with a high productivity providing the large gastropods with sufficient food. However, conditions were too eutrophic for sessile filter feeders including metazoan reef builders.