21. what era is known as the \age of invertebrates\?\n- a) precambrian\n- b) paleozoic\n- c) mesozoic\n- d)…

21. what era is known as the \age of invertebrates\?\n- a) precambrian\n- b) paleozoic\n- c) mesozoic\n- d) cenozoic\n22. what significant event marks the end of the mesozoic era?\n- a) the cambrian explosion\n- b) the permian - triassic extinction\n- c) the cretaceous - paleogene extinction\n- d) the great oxygenation event\n23. what is the primary characteristic of the cenozoic era?\n- a) dominance of reptiles\n- b) diversification of mammals\n- c) emergence of multicellular life\n- d) formation of rodinia\n24. what era saw the emergence of the first complex multicellular organisms?\n- a) paleozoic\n- b) precambrian\n- c) mesozoic\n- d) cenozoic

21. what era is known as the \age of invertebrates\?\n- a) precambrian\n- b) paleozoic\n- c) mesozoic\n- d) cenozoic\n22. what significant event marks the end of the mesozoic era?\n- a) the cambrian explosion\n- b) the permian - triassic extinction\n- c) the cretaceous - paleogene extinction\n- d) the great oxygenation event\n23. what is the primary characteristic of the cenozoic era?\n- a) dominance of reptiles\n- b) diversification of mammals\n- c) emergence of multicellular life\n- d) formation of rodinia\n24. what era saw the emergence of the first complex multicellular organisms?\n- a) paleozoic\n- b) precambrian\n- c) mesozoic\n- d) cenozoic

Answer

Brief Explanations:

  1. The Paleozoic era is known as the "Age of Invertebrates" as it saw a great diversification of invertebrate life - forms.
  2. The Cretaceous - Paleogene extinction event marks the end of the Mesozoic era, which led to the extinction of the dinosaurs.
  3. The primary characteristic of the Cenozoic era is the diversification of mammals, which became the dominant land animals after the extinction of dinosaurs.
  4. The Precambrian era saw the emergence of the first complex multicellular organisms.

Answer:

  1. b) Paleozoic
  2. c) The Cretaceous - Paleogene extinction
  3. b) Diversification of mammals
  4. b) Precambrian