More than 500 million years ago, something in the ocean changed. [–> Some creatures evolved to build their own hard-shelled exterior. Others grew to sizes never seen before as the amount of oxygen on the planet’s surface finally reached a level high enough for complex creatures to exist. [–> Most important, for about 10 million … Read more
Over the past 500 million years, vertebrates have evolved into a dizzying variety of forms, from hummingbirds to elephants, bullfrogs to hammerhead sharks, not to mention our special species of upright monkeys. But among all that diversity, vertebrates share some important characteristics. We all have a backbone made of, for example, vertebrae, together with a … Read more
Sign up for CNN’s Wonder Theory science newsletter. Explore the universe with news about fascinating discoveries, scientific developments and more. The idea of unexpectedly coming face to face with a spider-like creature is enough to horrify any arachnophobe, let alone encountering one with large, spiky legs. But that’s exactly what roamed what is currently northeastern … Read more