Hesperornithoides miessleri

Hesperornithoides is a small troodontid theropod from the Late Jurassic of Wyoming. As a paravian dinosaur it would have had wings and presumably a tail fan. The type (and so far only) specimen, WYDICE-DML-001, was found curled up in a sleeping pose similar to that of fellow troodontid Mei long. Hesperornithoides is one of the few well-preserved small predatory dinosaurs from the Morrison Formation, where it must have hunted frogs, lizards, small/baby dinosaurs and other prey suitable for a sub-1 m (3 foot) predator that weighed about as much as a house cat.

The proportions of Hesperornithoides show it was clearly not flying, but the presence of a non-flying Late Jurassic troodontid helps clarify the distribution of where, when and how often flight evolved among paravian theropods.