Leave tracks, not bones – a diverse Middle Jurassic dinosaur fauna from Denmark, revealed only by tracks

The Middle Jurassic is characterised by a worldwide scarcity of dinosaurian body fossils. Especially in Europe, ichnological data have become an increasingly important source of information for dinosaurian communities. The Aalenian–Bathonian Bagå Formation on the island of Bornholm (Denmark) has so far yielded tracks preserved as natural casts on the underside of sandstone beds, reflecting a dinosaurian fauna comprising two sizes of sauropods, a medium-sized theropod, thyrephorans and small ornithopods. The only skeletal evidence so far recovered from the formation is a skull fragment of a thalattosuchian crocodile. The recent recovery from the Bagå Formation of a hypichnial, deeply imprinted ornithopod track, preserved as a natural sandstone cast, adds to the sparse Middle Jurassic vertebrate record not only of Denmark but also of Europe.