Lesothosaurus diagnosticus was one of the most primitive and earliest ornithischians, or "bird-hipped" dinosaurs ... had a small head with very large eyes, short front legs with grasping hands ...

But researchers didn't know any of these details at first; originally, they found only the dinosaur's skeleton but not the head. Even so ... horns in front of its eyes and a crest that ran ...

so the dinosaur was likely quite light, as well. Its brain was about the size of a walnut, which is more or less average for sauropods, Sereno says. Its head is what really stands out about ...