Answer:
Researchers initially built up the geologic time scale by considering rock layers and record fossils around the world. With this data, researchers put in Earth's stone layers in request by relative age. Afterward, radioactive dating decided the supreme age of the divisions in the geologic time scale.
1. <span>composed of cells with cell walls
2. </span><span>Vertebrates contain a backbone, while invertebrates do not.</span>
