Question

Which characteristic defines the Paleozoic era?

Simple, one-celled life forms were dominant.



Reptiles became dominant after a mass extinction.

Mammals and other warm-blooded animals became dominant.


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

Answer 1

Explanation:

The Paleozoic (“old life”) era is characterized by trilobites, the first four-limbed vertebrates, and the origin of land plants.

Answer 2

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

The Paleozoic (“old life”) era is characterized by trilobites, the first four-limbed vertebrates, and the origin of land plants.

Paleozoic, or Paleozoic, a broad range of geological times, from about 542 to 251 million years ago. From the Greek meaning "old life", this is the first era of the Phanerozoic, followed by the Mesozoic. It is divided into six periods: (from oldest to newest) Cambrian, Ordovician, Silurian, Devonian, Carboniferous and Permian. During the early Paleozoic, much of North America was covered by warm, shallow seas with many coral reefs.

Fossils from this period include marine invertebrates and primitive fish; The plants consisted mainly of seaweed, with some moss and ferns. By the end of the Paleozoic, large areas of swamp forest covered most of the northern continents. Plants and animals flourished. Amphibians left the oceans to live on land, reptiles evolved into fully terrestrial life forms, and insect life began. Ferns grew to the size of trees and emerged as the forerunners of conifers.

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