Here's a breakdown of the timeline:
* Early Life: The first life forms on Earth were single-celled organisms, appearing billions of years ago.
* Invertebrates: Invertebrates, like jellyfish and worms, arose long before mammals.
* Fish: Fish were among the first vertebrates, evolving around 500 million years ago.
* Amphibians, Reptiles, Dinosaurs: These groups evolved before mammals.
* Mammals: Mammals evolved from a group of reptiles called synapsids, around 200 million years ago.
So, while mammals are an important and diverse group, they are relatively recent arrivals on the evolutionary scene.