Question

Fishes originated in this period:

• A. Devonian
• B. Silurian
• C. Triassic
• D. Ordovician

Hint:

Remember: Ordovician = Origin of fishes, Devonian = Age of Fishes.

Answer 1

The Correct Option is D

Concept: The geological time scale records the appearance and diversification of major groups of organisms on Earth. Different eras and periods are associated with the origin and evolution of particular life forms. Understanding these evolutionary milestones is important in studying the history of life.

Step 1: Recall the origin of vertebrates. The earliest vertebrates evolved in ancient seas. Primitive jawless fishes appeared during the Ordovician Period of the Paleozoic Era. These early fishes represented some of the first vertebrate animals on Earth and laid the foundation for the later evolution of more advanced fish groups.

Step 2: Examine the Devonian Period. The Devonian Period is commonly called the “Age of Fishes” because fishes underwent extensive diversification during this time. However, diversification does not mean origin. Fishes had already appeared before the Devonian Period. Therefore Devonian is not the correct answer.

Step 3: Eliminate the remaining options. Silurian Period witnessed further development of fishes but not their first appearance. Triassic Period belongs to the Mesozoic Era and occurred much later than the origin of fishes. Therefore both options are incorrect.

Step 4: State the conclusion. Since the earliest fishes originated during the Ordovician Period, \[ \boxed{\text{Ordovician}} \] is the correct answer.