Which characteristic defines the Paleozoic era?(1 point)

Question

Responses

Simple, one-celled life forms were dominant.
Simple, one-celled life forms were dominant.

Mammals and other warm-blooded animals became dominant.
Mammals and other warm-blooded animals became dominant.

Animals with shells and hard parts were dominant for the first time.
Animals with shells and hard parts were dominant for the first time.

Reptiles became dominant after a mass extinction.

Answer 1

The characteristic that defines the Paleozoic era is:

Animals with shells and hard parts were dominant for the first time.

This era, which lasted from about 541 to 252 million years ago, is marked by the Cambrian Explosion, a period during which a significant diversification of life forms occurred, including the emergence of many organisms with hard parts.