24. History of Life on Earth

What is the most significant difference between Precambrian and Paleozoic life-forms?

According to fossil evidence, when did life on Earth first arise?

In the context of the history of life on Earth, gradualism is a pattern of evolution in which:

When did life (organisms) first appear on Earth?

What discovery led scientists to conclude that life on Earth is at least 3.5 billion years old?

What major event occurred during the Paleozoic Era?

Approximately how many years ago did invertebrates become common on Earth?

Which of the following periods is considered one of the most significant transitional periods in the history of living organisms?

During which era did the first fish develop?

Which event marks the end of the Mesozoic Era and is associated with the mass extinction of the dinosaurs?

Which of the following statements about the Cambrian Explosion is NOT true?

Which of the following statements is true regarding the Mesozoic Era?

During which eon did the first prokaryotic life forms appear on Earth?

In which of the following time periods were dinosaurs the dominant creatures?

Approximately how long ago did the first plants appear on Earth?