ASBOG Practice Exam

During the Paleozoic era, which groups of organisms first appeared?

1. Invertebrates, fish, and amphibians

2. Mammals and reptiles

3. Birds and insects

4. Amphibians and mammals

The correct answer is: Invertebrates, fish, and amphibians

The Paleozoic era, which lasted from approximately 541 to 252 million years ago, is notable for the appearance of a diverse array of life forms, particularly invertebrates, fish, and amphibians. This era began with the Cambrian explosion, a significant event marked by a rapid increase in the diversity of life, especially marine invertebrates such as trilobites, brachiopods, and mollusks. Following the Cambrian period, fish emerged as the first vertebrates during the Ordovician period, with early jawless fish being the predominant form. By the Devonian period, often referred to as the "Age of Fishes," more advanced groups of fish began to flourish. Additionally, the transition of life from water to land occurred during this era, with the appearance of the first amphibians in the late Devonian period. These early amphibians evolved from ancestral fish, marking a significant evolutionary step. In contrast, mammal and reptile lineages did not appear until later, during the Mesozoic era. Birds and insects also emerged after the Paleozoic, with insects appearing earlier in the Carboniferous but not reaching significant diversity until later. Therefore, the appearance of invertebrates, fish