Which era is dated about 540 to 500 million years ago and is known for an explosion in life forms?

Which era is dated about 540 to 500 million years ago and is known for an explosion in life forms?

• A. Paleozoic Era
• B. Cambrian Era
• C. Precambrian Era
• D. Mesozoic Era

Answer: (B)

During the Cambrian period, roughly 540 to 500 million years ago, life in the oceans underwent a rapid diversification known as the Cambrian explosion. In a relatively short time, many major animal groups first appear in the fossil record, including early arthropods like trilobites, mollusks, and echinoderms, often with hard shells or other distinctive features. This sudden burst in variety marks a major turning point in how complex life looked and functioned, which is why this era is famous for its dramatic increase in life forms. The dates given align with the early Cambrian timeframe. Earlier life (Precambrian) was mostly simple and single-celled, while later eras (Paleozoic after Cambrian, followed by Mesozoic) build on what begins in the Cambrian.

During the Cambrian period, roughly 540 to 500 million years ago, life in the oceans underwent a rapid diversification known as the Cambrian explosion. In a relatively short time, many major animal groups first appear in the fossil record, including early arthropods like trilobites, mollusks, and echinoderms, often with hard shells or other distinctive features. This sudden burst in variety marks a major turning point in how complex life looked and functioned, which is why this era is famous for its dramatic increase in life forms. The dates given align with the early Cambrian timeframe. Earlier life (Precambrian) was mostly simple and single-celled, while later eras (Paleozoic after Cambrian, followed by Mesozoic) build on what begins in the Cambrian.