The Late Triassic rocks cropping out at the Jameson Land Basin (East Greenland) forming the Fleming Fjord Formation are rich in vertebrate fossils, recording all the main groups of vertebrates known from the epoch, including some unique species. This PhD project, standing on the fossils findings by of the US-Danish expeditions to East Greenland during the late 1980’s, 1190’s, early 2000’s, and the new expeditions that we participated from 2012 to 2016. The main structure of this thesis follows the phylogenetic order of the Late Triassic vertebrate fauna from Greenland, providing the most complete to-date synthesis on the known Paleozoic and Mesozoic fossil tetrapods of Greenland, with a unique photographical record of all the Greenlandic holotypes, including some of the most iconic fossils for paleontology (Chapter 1). The tetrapod fossil record of the Paleozoic and Mesozoic of Greenland includes, at least, 30 taxa. A final section including new data on phytosaur and sauropodomorph remains has been added to the original article. Discoveries during the 2012 and 2016 expeditions allowed the description of a new lungfish Ceratodus tunuensis (Dipnoi: Ceratodontidae). Chapter 3 is the last up-to-date of the published papers that compose this thesis. It is about the description of a new species of cyclotosaur amphibian, Cyclotosaurus naraserluki (Temnospondyli: Capitosauroidea), a salamander-like freshwater predator with a skull over half a meter long. The yet unpublished Chapters 4–6 includes the description of three new species from the Late Triassic of the Flemming Fjord Fm.: a Stagonolepididae aetosaur, a basal Testudinata, and a basal theropod dinosaur. Chapter 7 concludes this thesis, assessing the paleoecological, paleogeographic, paleoenvironmental, and paleoclimate implications of the Fleming Fjord faunal assemblage in comparison with coeval faunas from Europe and North America, linking the vertebrate fauna of Greenland closely related to Europe than North America.