Nothosaur tracks from the Middle Triassic of Spain suggest a global distribution for distinctive swim track assemblages

Abstract

The first marine reptiles are known from the late Early Triassic, including ichthyosaurs, nothosaurs and pachypleurosaurs, while placodonts and thalattosaurs emerged soon after, in the early Middle Triassic (Chen et al. 2012;Liu et al. 2014). These marine reptiles swam in shallow seas around Pangaea, feeding generally on small to large prey ranging from crustaceans and other invertebrates to fishes. In addition, the larger marine reptiles, such as some ichthyosaurs, thalattosaurs and nothosaurs, may also have fed on smaller marine reptiles, while the placodonts specialized in browsing and crushing oysters (Motani 2009;