Question

Contrast Proterozoic and Phanerozoic Eons.(1 point) Responses Phanerozoic eon animals were single cells or more primitive, and the Earth was just forming. Protozoic eon animals were multicellular and complex, Earth had formed continents, and continental drift was beginning to happen. Phanerozoic eon animals were single cells or more primitive, and the Earth was just forming. Protozoic eon animals were multicellular and complex, Earth had formed continents, and continental drift was beginning to happen. Proterozoic eon animals were single cells or more primitive, and the Earth was just forming. Phanerozoic eon animals were multicellular and complex, Earth had formed continents, and continental drift was beginning to happen. Proterozoic eon animals were single cells or more primitive, and the Earth was just forming. Phanerozoic eon animals were multicellular and complex, Earth had formed continents, and continental drift was beginning to happen. Proterozoic eon animals did not exist, and the Earth had only the Pangaea supercontinent. Phanerozoic eon animals began when dinosaurs developed, Earth had formed continents, and continental drift was beginning to happen. Proterozoic eon animals did not exist, and the Earth had only the Pangaea supercontinent. Phanerozoic eon animals began when dinosaurs developed, Earth had formed continents, and continental drift was beginning to happen. Proterozoic eon animals were fish, amphibian, and reptiles living on Pangaea. Phanerozoic eon animals were mammals, and Earth had formed Laurasia and Gondwana continents.

Answer 1

To accurately contrast the Proterozoic and Phanerozoic Eons, we can summarize the key differences as follows:

1. Proterozoic Eon (approximately 2.5 billion to 541 million years ago):

   • Characterized by the predominance of simple, single-celled organisms, such as bacteria and archaea, with multicellular life beginning to emerge towards the end of this eon (e.g., early algae and simple multicellular organisms).
   • The Earth saw significant geological activity, including the formation of stable continents and the beginning of continental drift, but complex life forms were largely absent.
   • Major atmospheric changes occurred, notably the Great Oxygenation Event, which dramatically increased free oxygen levels in the atmosphere.

2. Phanerozoic Eon (approximately 541 million years ago to the present):

   • Marked by the emergence and diversification of multicellular life forms, including a wide variety of animals and plants. This is where complex life flourished, starting with the Cambrian Explosion.
   • Significant geological changes continued, and the continents moved to their current positions, with the formation and breakup of supercontinents like Pangaea.
   • Notable eras within this eon include the Paleozoic, Mesozoic (which includes the age of dinosaurs), and Cenozoic (the age of mammals).

In summary:

• The Proterozoic Eon was dominated by simple life forms and saw the early development of multicellularity, while the Phanerozoic Eon is known for its rich diversity of complex life, including multicellular organisms, and significant geological developments, including continental drift and the formation of the continents.