Trilobites are an example of

Answer 1

Trilobites (meaning "three lobes") are a well-known fossil group of extinct marine arthropods that form the class Trilobita. The first appearance of trilobites in the fossil record defines the base of the Atdabanian stage of the Early Cambrian period (526 million years ago) and flourished throughout the lower Paleozoic era before beginning a drawn-out decline to extinction when, during the Devonian, all trilobite orders, with the sole exception of Proetida, died out. Trilobites finally disappeared in the mass extinction at the end of the Permian about 250 million years ago.

When trilobites first appeared in the fossil record they were already highly diverse and geographically dispersed. Because trilobites had wide diversity and an easily fossilized exoskeleton an extensive fossil record was left, with some 17,000 known species spanning Paleozoic time.
A Trilobite is a fossil. The fossilised remains of a type of animal called an arthropod that lived in the sea between 521 and 250 million years ago. They are now extinct.

They are called "trilobites" because their body shapes have 3 lobes. They looked a bot like woodlice.

I have made a link to a picture of a trilobite below.

Answer 2

Ancestors of trilobites would be arthropods in the same broad group to which trilobites belong (the Arachnomorpha) but lacking one or more of the characteristics that distinguish trilobites. Perhaps one of the most important trilobite characteristic feature is exoskeleton calcification. Without a calcified skeleton, the chances of fossilization are extremely low. This may explain why the ancestors of trilobites are not clearly known. Arachnomorph groups such as the Helmetiidae, Naraoiidae, Tegopeltidae, and Xandarellidae might resemble the ancestors of trilobites. Each of these is uncalcified, and only rarely preserved, as at the Burgess Shale in Canada and Chengjiang, in China.

Answer 3

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