What characteristic defines the palozonic era simple one-celled life forms were dominant animals with shells and hard parts were dominant for the first time mammals and other warm-blooded animals became dominant reptiles became dominant after a mass extinction

Answer 1

The characteristic that defines the Paleozoic Era is that simple one-celled life forms were dominant, and it was during this time that animals with shells and hard parts became prominent. This era saw the development of many marine life forms, with the Cambrian Explosion marking a significant increase in the diversity of life, including the emergence of early vertebrates. However, it was during the later Mesozoic Era when reptiles became dominant, and mammals and warm-blooded animals began to rise after that period.