GEOLOGY
STRATIGRAPHY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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They are found in ancient oceans.
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They are found all over the world.
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They are found in deep sedimentary rocks layers.
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They are among the first fossils to attract widespread attention.
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Detailed explanation-1: -Because they evolved rapidly, and moulted like other arthropods, trilobites serve as excellent index fossils, enabling geologists to date the age of the rocks in which they are found.
Detailed explanation-2: -Because their shells were made of the mineral calcite, like those of crabs or clams, trilobites are well represented in the fossil record, preserved in sites all over the world from the United States to China.
Detailed explanation-3: -Trilobites were extremely successful in the Cambrian. This is because they had many new evolutionary traits, including a hardened outer skeleton, which protected them from the new predators lurking in the ancient seas, and allowed them to move of their own accord to find food.
Detailed explanation-4: -Because they were mobile animals, they tended to inhabit large, even global areas. They were also hard-shelled invertebrates, so they fossilized easily. These fossils are large enough to study without a microscope.
Detailed explanation-5: -Normally, the membranes that hold the skeleton together will decay and the skeleton will fall apart. The various pieces will be scattered by waves, currents or scavenging animals. This means that we usually find isolated parts of the head, tail and thorax. Like all arthropods, trilobites grew by molting.