The beginning of the ______is marked by the appearance of the first life forms with hard parts.
A) Precambrian
B) Paleozoic
C) Mesozoic
D) Cenozoic

Question

Quizplus · Accepted Answer

The Paleozoic era is marked by the "Cambrian Explosion," which saw the appearance of the first life forms with hard parts, such as shells and skeletons. The Precambrian era precedes this and is characterized by simple life forms without hard parts, while the Mesozoic and Cenozoic eras follow the Paleozoic and are known for the rise of the dinosaurs and the evolution of mammals, respectively.

The Beginning of the ______Is Marked by the Appearance of the First