- In my world, there's an era when only some 20 visible (big enough to see with the naked eye; all other animal life forms are microscopic) animal types lived on the planet. Mammals such as wolves, livestock animals, rodents, small wild cats, as well as a few different types of fish, bird, insect, reptile, and arachnid species.
- Most of the animal types link with each other in a food web and with the ecosystems on the planet.
- Some of the creatures prefer certain climates over others.
- There isn't that much variety in visible animal types (environment or mutational adaptations).
Could such an era be somewhat scientifically possible?
The weather and biome conditions resemble those of Earth.