​Preserved records of prehistoric organic activity such as tracks, trails, burrows, and nests are called ____.

The earliest atmosphere was likely composed of ___________ and __________.

In a sequence of undisturbed sedimentary rocks, the oldest fossils will be ____.​

Since the appearance of Cro-Magnons, human evolution has been:

During the ________ period of the Late Paleozoic, plants rapidly diversified.

The ancestor of all living carnivores is a(n):

The richest assemblages of dinosaur fossils formed in the __________________ during post-flood deposition.

Depositional environments have unique physical, biologic and chemical processes. 

What occurred 14 billion years ago?

During the Pleistocene, how much lower was sea level than present day?