Question

which is a difference between the paleozoic and mesozoic era?
animals lived in the water during the mesozoic and on land in the paleozoic.
the first birds emerged in the paleozoic era while mammals first emerged in the mesozoic.
many different species of dinosaurs lived in the mesozoic, but they all died off in the paleozoic.
animal complexity increased during the paleozoic while the first flowering plants appeared in the mesozoic era.

Explanation:

• Option 1: Animals lived in water in Paleozoic (e.g., trilobites) and on land in Mesozoic (e.g., dinosaurs). So this option is wrong.
• Option 2: First birds (Archaeopteryx) emerged in Mesozoic (Late Jurassic), mammals first emerged in Triassic (Mesozoic). So this option is wrong.
• Option 3: Dinosaurs lived in Mesozoic and died off at the end of Mesozoic (Cretaceous - Paleogene extinction event). So this option is wrong.
• Option 4: During Paleozoic, there was an increase in animal complexity (Cambrian explosion). First flowering plants (angiosperms) appeared in Mesozoic (Cretaceous). This option is correct.

Answer:

Animal complexity increased during the Paleozoic while the first flowering plants appeared in the Mesozoic era.