______________ can be used to date fossils in rocks to give an approximate age.
Complex organisms with gills and lungs were major life forms that existed in the_____________.
Eons, eras, periods, and epochs, are all examples of ____________time.
Thylacosmilus is a marsupial, and Smilodon is a mammal. Thylacosmilus and Smilodon both have saber teeth, but they do not share an ancestor that had saber teeth. What are saber teeth for these organisms?
Shifts in the rock layer locations cannot account for gaps in the rock record
Scientists notice structural similarities between fossils of a land animal and an aquatic organism. They know the similarities are not a result of the two organisms having to adapt to similar environments. What can they attribute the structural similarities to?
Mammals evolved into larger organisms and began subdividing into various species in the _____________.
Which best describes the fossil record?
Why are the Miller-Urey experiments essential to the theory of evolution?
Geologic time is divided into units based upon types of ____.
Which statement is true of the undisturbed rock layers shown?
Humans first appeared in the Cenozoic Era.
The Paleozoic Era is the longest time period in the history of Earth.
Determining the order of events and the relative age of rocks by examining the position of rocks in a sequence is called ____.
If a layer of sandstone lies on top of a layer of limestone in which a 300-million-year-old fossil is found, and there are no unconformities, the layer of sandstone must be ____.
Scientists used major changes in life forms in the fossil record to form the geologic time scale.
Scientists are able to determine the relative age of rocks in specific years.
____ dating uses the properties of atoms in rocks and other objects to find their ages.
Early land animals had gills as well as lungs.
Please select the word from the list that best fits the definition
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