Une grande feuille de rock avec beaucoup de trilobites dans elle. Les Trilobites "trois-ont disparu des lobes arthropodes qui forment la classe Trilobita.
4608 x 3690 px | 39 x 31,2 cm | 15,4 x 12,3 inches | 300dpi
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A large sheet of rock with many trilobites in it. Trilobites "three-lobes" are extinct arthropods that form the class Trilobita. They appeared in the Early Cambrian period and flourished throughout the lower Paleozoic era before beginning a drawn-out decline to extinction when, during the Late Devonian extinction, all trilobite orders, with the sole exception of Proetida, died out. The last of the trilobites disappeared in the mass extinction at the end of the Permian about 250 million years ago (m.y.a.). Trilobites are very well-known, and possibly the second-most famous fossil group, after the dinosaurs. When trilobites appear in the fossil record of the Lower Cambrian they are already highly diverse and geographically dispersed. Because of their diversity and an easily fossilized exoskeleton, they left an extensive fossil record with some 17, 000 known species spanning Paleozoic time
