A tiny seaweed fossil from a billion years ago may help scientists understand how the first plants came ashore and evolved for life on land.
Algae in a shallow river, the Afon Glaslyn in Wales. Hundreds of millions of years ago, similar algae adapted to survive temporarily outside of the water, which may have kicked off the evolution of green land plants.PHOTOGRAPH: ALAMY
AROUND 500 MILLION years ago—when the Earth was already a ripe 4 billion years old—the first green plants appeared on dry land. Precisely how this occurred is still one of the big mysteries of evolution. Before then, terrestrial land was home only to microbial life. The first green plants to find their way out of the water were not the soaring trees or even the little shrubs of our present world. They were most likely soft and mossy, with shallow roots and few of the adaptations they would later evolve to survive and thrive on dry land. And though scientists agree that these plants evolved from some kinds of seaweed, we know comparatively little about those green algal ancestors…