Question

Until recent discoveries suggested otherwise, animals existing before the Cambrian period were believed to be:

a) Invertebrates
b) Fish
c) Amphibians
d) Reptiles

Answer 1

Animals existing before the Cambrian period were believed to be invertebrates, and the Cambrian period marked a rapid evolution of new animal phyla and diversity.

Step-by-step explanation:

Until recent discoveries suggested otherwise, animals existing before the Cambrian period were believed to be invertebrates. The Cambrian period, occurring between approximately 542-488 million years ago, marks the most rapid evolution of new animal phyla and animal diversity in Earth's history. Many types of primitive animals called sponges evolved during this period, and small ocean invertebrates called trilobites became abundant.