Dinosaur footprints from the Sao Khua Formation (Early Cretaceous) of Phu Kao National Park,Northeast Thailand

The first documented dinosaur footprints from Southeast Asia were theropod footprints found in Thailand at Phu Luang Wildlife Sanctuary. Since then, Mesozoic vertebrate footprints have been discovered in twelve different localities in Thailand. In 2000, dinosaur footprints were found in Phu Kao National Park in Northeastern Thailand, however, they have never been studied in detail. The following study presents the first map, the complete measurements, the geology, and stratigraphy of the site and surrounding area. The study discusses the nature of the trackmaker and the digitigrade character of the footprints. This discovery represents the first documented occurrence of dinosaur footprints inside the Early Cretaceous Sao Khua Formation from Thailand.     

Quantitative analysis of horizontal bioturbation from Brioverian (Ediacaran - Fortunian) deposits of Brittany (Armorican Massif,NW of France)

Ediacaran-Cambrian bioturbation on bedding planes provides physical and chemical data about the environmental conditions and biological activities of early metazoans. We propose a quantitative method to estimate horizontal disruption of the substrate using bedding-plane trace fossils from Brioverian deposits. This methodology provides the first quantitative analysis of the trace fossil assemblage from the Armorican Massif (Brittany, NW of France). The Ediacaran-Cambrian transition within the Brioverian series is characterized by the abundance of simple and horizontal trace fossils such as Helminthopsis, Helminthoidichnites, and Palaeophycus as well as rare Gordia and Spirodesmos. Recent U-Pb dating has been carried out on detrital zircon grains from the upper Brioverian series suggesting a late Ediacaran to Fortunian age of the fossiliferous deposits (ca. 550 to 530 Ma). With Arc-Gis software, we use a semi-quantitative approach to estimate the relative 2D bioturbation rate recorded on bedding planes. The dataset is used to discuss the feeding strategies and how the seafloor ecospace was colonized by the early bilaterian metazoans. This approach combines new values such as: the length of a trace fossil, the surface of a trace, the cumulative length, and the cumulative surfaces from all of the ichnofossils recorded on the same slate surface, to finally suggest that the bioturbation rate of the microbial grazers impacted the use of the seafloor ecospaces and feeding strategies through the biomats.