- The timeline shows the geological time scale, divided into eons, eras, and periods, with representative organisms for each interval.
- The Hadean Eon (before 4.0 billion years ago) is shown as barren, indicating no known life.
- The Archean Eon (4.0–2.5 billion years ago) marks the origin of life, with first living organisms like bacteria.
- The Proterozoic Eon (2.5 billion–541 million years ago) includes the rise of more complex single-celled organisms, multicellular life, and early animals such as sponges and jellyfish.
- The Paleozoic Era (541–252 million years ago) begins with the Cambrian explosion of diverse animal life, followed by fish, land plants, insects, amphibians, reptiles, and eventually mammals in later periods.
- The Mesozoic Era (252–66 million years ago), known as the age of dinosaurs, features dominant reptiles, the first birds, and flowering plants.
- The Cenozoic Era (66 million years ago–present) is marked by the dominance of mammals, including whales, elephants, and eventually humans in the Quaternary period.
- The timeline illustrates the progression of life from simple to complex forms over billions of years, correlated with major geological periods.
Parent Tip: Review the logic above to help your child master the concept of geologic time scale worksheet.
