New dicynodonts (Therapsida, Anomodontia) from the Early Triassic of Laos: implications for the tetrapod recovery after the Permian–Triassic mass extinction and the paleobiogeography of Southeast Asian Blocks

International audience; The dicynodonts are an emblematic group of herbivorous therapsids, which have survived thePermian–Triassic (PT) crisis. Laotian dicynodonts from stratigraphically well-constrained beds, using U–Pbon zircon dating, bring new insights into terrestrial faunas of Southeast Asia during the Early Triassic. Theyhave already briefly been described but their phylogenetic relationships were never been investigated. Reexaminationof the Laotian dicynodonts, three well-preserved skulls, indicates that they belong to two newspecies. Our phylogenetic analysis within Dicynodontia indicates that 1) gen. et sp. nov. 1 is closely relatedto some ”Dicynodon ”- grade taxa; and 2) gen. et sp. nov. 2 is a stem taxon to Kannemeyeriiformes. Thephylogenetic affinities of these new Laotian dicynodonts allow to discuss about the recovery of theterrestrial tetrapods during the Early Triassic: the survival of a Permian lineage across the PT crisis and/or arapid recovery with a new occurrence in the Early Triassic. The Laotian dicynodonts also shed new light onthe debated paleogeographic issues concerning the evolution of Southeast Asia from the late Paleozoic tothe early Mesozoic, particularly on the timing of the collision between the Indochina, the South China andthe North China blocks. The Early Triassic age of the two new Laotian dicynodonts, their essentiallyterrestrial lifestyle, and the phylogenetic affinities between gen. et sp. nov. 2 and Early Triassic ChineseKannemeyeriiformes, suppose a land connection between the Indochina Block and other dicynodontbearing continents as early as the Early Triassic.