Day 07: From Lake Nyasa in the mid-Triassic, some 245 million years ago, Nyasasaurus parringtoni is the oldest known true dinosaur. Like with the evolution from dinosaurs to birds, it can be hard to say when the first dinosaur was, and there's some argument that Spondylosoma may be the oldest. Or it may not be. In the meantime, Nyasasaurus is, unless you're one of those arguing that it's not a dinosaur either. Evolution is complicated. Especially when you only have a few bones.