OBJECTIVE FORESTRY

Detailed explanation-1: -The earliest trilobites known from the fossil record are redlichiids and ptychopariid bigotinids dated to around 520 million years ago.

Detailed explanation-2: -The oldest known fossils, in fact, are cyanobacteria from Archaean rocks of western Australia, dated 3.5 billion years old. This may be somewhat surprising, since the oldest rocks are only a little older: 3.8 billion years old! Cyanobacteria are among the easiest microfossils to recognize.

Detailed explanation-3: -Trilobites are a group of extinct marine arthropods that first appeared around 521 million years ago, shortly after the beginning of the Cambrian period, living through the majority of the Palaeozoic Era, for nearly 300 million years.

Detailed explanation-4: -Like many invertebrate animals living today, including crustaceans, spiders and insects, trilobites were arthropods, belonging to the phylum Arthropoda. Geologists know that they were marine animals because of the rocks in which they are found and the other types of fossils associated with them.