Abstract In Laos, dicynodonts have long been known only from one specimen, now lost, a partial skull discovered by Counillon in the purple beds of the area of Luang Prabang, and initially described by Repelin as Dicynodon incisivum . Subsequent researchers attributed the specimen either to the Late Permian genus Dicynodon or to the Early Triassic genus Lystrosaurus. Recent Franco-Laotian expeditions have gathered, from the same purple beds, a collection of tetrapods composed mainly of dicynodonts. They can all be ascribed to Dicynodon , and the available evidence suggests that the purple beds are Late Permian in age. The genus Lystrosaurus remains unknown in Laos.

Abstract The papers in this volume concentrate on the terminal Palaeozoic and Mesozoic non-marine formations of Thailand and Laos. Similar formations are also known from other countries in mainland SE Asia, such as Malaysia (where several non-marine plant-bearing formations of Jurassic to Cretaceous age are known: Lee et al. 2004), Vietnam and Cambodia (where red beds similar to those of the Khorat Group of Thailand are widespread: Workman 1977; Fontaine & Workman 1978). However, the non-marine Late Palaeozoic and Mesozoic fossils of Thailand and Laos have received much more attention than those of neighbouring countries, from which little has been reported. What we know of the Late Palaeozoic and Mesozoic ecosystems of SE Asia is therefore very largely based on the Thai and Lao records. The study of these Late Palaeozoic and Mesozoic non-marine assemblages began in the 1890s when French geologists took part in expeditions to the Lao principalities that served both a scientific and a political purpose (the latter being clearly predominant, as the more or less avowed aim was to bring that area under French influence). Counillon's 1896 report of a dicynodont skull from the vicinity of Luang Prabang thus is a landmark in the history of vertebrate palaeontology in SE Asia

Abstract Historical studies on the exploration of SE Asia reveal interesting points concerning the geology and palaeontology of this part of the world: the first geological description of northern Laos was published in 1896 by the French geologist J. B. H. Counillon, a member of the famous Pavie Mission (1879–1895). Although scientific notes are rare in the literature about the Pavie Mission, which dealt with diplomacy and politics, Counillon's studies are very informative: they contain accurate observations on the geomorphology, hydrography, stratigraphy and palaeontology of the Mekong River and its banks. Counillon explored the dangerous region of Luang Prabang (northern Laos) with Captain Cupet. He discovered the first fossil tetrapods from Laos, and, with the help of Vasseur and Repelin, correctly referred them to dicynodont mammal-like reptiles.