2. Early Cambrian, 541 million to 510 million years ago
Three billion years after the earliest stromatolites but still 200 million years before the first dinosaurs, life hit its stride. This epoch—the onset of the Cambrian era—is known as the “Cambrian Explosion” for the amount of life that burst onto the scene. All time before the Cambrian Period is merely referred to as Precambrian, if that helps your understanding of this moment’s gravity.
The Cambrian ushered in a bizarre suite of sea creatures, many of which are preserved in the Burgess Shale that stretches across the Canadian Rockies. (Life wasn’t really a thing on land yet, but the waters were hoppin’.) The shifting of Earth’s geology means that the ancient seafloor is now marvelously preserved in the mountaintops. Our beloved trilobites enter the fray. Cambroraster falcatus, named for its resemblance to Star Wars’ Millennium Falcon, slurped up prey in its vacuum-like mouth. A 3-foot predatory shrimp called Anomalocaris lurked. I’d call them weird, but we’re fleshy primates that travel in metal tubes and stare at pieces of glass all day, so…
