They call me the wanderer – Neurovascular anatomy of dwarfed dinosaur implies precociality in sauropods

Macronaria, a group of mostly colossal sauropod dinosaurs, comprised the largest terrestrial vertebrates of Earth’s history. However, some of the smallest sauropods belong to this group as well. The Late Jurassic macronarianEuropasaurus holgeriis one of the best-known sauropods worldwide. So far, the braincase material of this taxon from Germany pended greater attention. With the aid of microCT, we report on the neuroanatomy of the almost complete braincase of an adult individual, as well as the inner ears of one other adult and several juveniles (also containing so far unknown vascular cavities). The presence of large and morphologically adult inner ears in juvenile material suggests precociality. Our findings add to the diversity of neurovascular anatomy in sauropod braincases and buttress the perception of sauropods as fast-growing and autonomous giants with manifold facets of reproductive and social behavior. This suggests that – apart from sheer size – little separated the island dwarfEuropasaurusfrom its large-bodied relatives.