Tiny fossil embryos curled up inside a clutch of African dinosaur eggs nearly 200 million years old hint at a remarkable story of evolution, scientists report -- the transformation of an early tribe of plant-eating animals only a few feet long that became, over millions of years, the largest animals ever to walk the Earth. The body design of the embryos suggests that as hatchlings, those young dinosaurs were obliged to walk on four legs, but grew up as two-legged adults, the scientists say, while the lumbering, long-necked animals that succeeded them were four-legged all their lives. And from the...