Trilobites (name meaning "Three Lobes") are a genus of marine arachnomorph arthropods that originated during the Early Cambrian Era in every ocean on Earth.
In the Series 1 episode "Water Dwellers" several Redlichia were brought to the park from Early Cambrian North America, 530 million years ago. Later in the episode "Eye of the Beast", several Isotelus were brought to the park from Late Ordovician North America, 450 million years ago. Both Trilobite species resides in the Primeval Aquarium Enclosure.