The geologic era in which animals with hard shells first appeared is the
A)Mesozoic.
B)Cenozoic
C)Paleozoic.
D)PreCambrian.

Question

Quizplus · Accepted Answer

The appearance of animals with hard shells is associated with the Paleozoic era, which lasted from about 541 million to 252 million years ago. This era is also known as the "Age of Invertebrates" due to the abundance of marine invertebrates, including those with hard shells like trilobites and brachiopods. The Mesozoic era followed and is known as the "Age of Dinosaurs," while the Cenozoic era is more recent and characterized by the rise of mammals. PreCambrian is not a valid answer as it predates the emergence of multicellular life, let alone animals with hard shells.

The Geologic Era in Which Animals with Hard Shells First