In a sequence of rock layers we find trilobite fossils at the bottom of rock layer 1 and dinosaur fossils directly above the fossil trilobites in layer 2.There are inclusions of trilobites in layer 2.We conclude that
A)dinosaurs were extinct long before trilobites came into existence.
B)dinosaurs are from the Cambrian Period.
C)by inclusion and faunal succession,layer 1 is older than layer 2.
D)there is no time gap between the rocks.

Question

Quizplus · Accepted Answer

The presence of trilobite fossils at the bottom of rock layer 1 and dinosaur fossils in layer 2 directly above the trilobites indicates that layer 1 is older than layer 2. The presence of trilobite inclusions in layer 2 also confirms this. This is known as the principle of faunal succession, which states that fossil organisms succeed one another in a definite and determinable order, and therefore, can be used to identify the relative ages of rock layers. The fact that there are no time gaps between the rocks is not indicated by the information given, so D is not correct. A and B are both incorrect because they contradict the known geological and paleontological records.

In a Sequence of Rock Layers We Find Trilobite Fossils