Which statements about geologic time are true? Check all that apply.

Question

Scientists developed the geologic time scale as they studied rock layers and index fossils.
The fossil record helps scientists describe life only in the seas and other bodies of water.
Precambrian time is the most recent time in Earth’s history.
Precambrian time makes up 88 percent of Earth’s history.
The first birds appeared during the Mesozoic Era.
The basic units of the geologic time scale are periods, eras, and centuries.
Humans appeared during the Cenozoic era.

Answer 1

Here are the true statements about geologic time from your list:

1. Scientists developed the geologic time scale as they studied rock layers and index fossils. - True
2. The fossil record helps scientists describe life only in the seas and other bodies of water. - False (The fossil record includes organisms that lived on land as well.)
3. Precambrian time is the most recent time in Earth’s history. - False (Precambrian time is the earliest and longest part of Earth's history.)
4. Precambrian time makes up 88 percent of Earth’s history. - True
5. The first birds appeared during the Mesozoic Era. - True
6. The basic units of the geologic time scale are periods, eras, and centuries. - False (The basic units are eons, eras, periods, and epochs.)
7. Humans appeared during the Cenozoic era. - True

So, the true statements are 1, 4, 5, and 7.