Our chosen fossil today is Eudibamus cursoris,which was first discovered in Germany and dated at 290 millions years old. This ancient parareptile (not a dinosaur, but appearing much earlier) was just 26 cm long and lived among the early amniotes in the early Permian. At this time, terrestrial vertebrates had rapidly diversified but were almost universally constrained to a fairly slow, heavy quadrupedal walk or trot, as indicated by the short, stocky limbs and robust limb girdles in fossil finds from this period (think modern crocodiles and lizards). However, the mostly complete skeleton of Eudibamus clearly has long hindlimbs, a slender body and long, fine tail, leading palaeontologists to infer that it might be the earliest fossil species discovered that was able to move bipedally – up to 60 million years before the first bipedal dinosaurs!
Image courtesy of David S. Berman et al. Read more about this work here.