appendage: A finger, leg, ear, antenna or other feature that sticks out from some creature and has some apparent specific function.
arthropod: Any of numerous invertebrate animals of the phylum Arthropoda, including the insects, crustaceans, arachnids and myriapods, that are characterized by an exoskeleton made of a hard material called chitin and a segmented body to which jointed appendages are attached in pairs.
Cambrian: A period of Earth’s history that lasted from about 541 million to 510 million years ago. It is one of the earliest periods in which fossils can be used to date rocks.
computer model: A program that runs on a computer that creates a model, or simulation, of a real-world feature, phenomenon or event.
crustaceans: Hard-shelled water-dwelling animals including lobsters, crabs and shrimp.
exoskeleton: A hard, protective outer body covering of many animals that lack a true skeleton, such as an insect, crustacean or mollusk. The exoskeletons of insects and crustaceans are largely made of chitin.
extinct: An adjective that describes a species for which there are no living members.
fossil: Any preserved remains or traces of ancient life. There are many different types of fossils: The bones and other body parts of dinosaurs are called “body fossils.” Things like footprints are called “trace fossils.” Even specimens of dinosaur poop are fossils. The process of forming fossils is called fossilization.
insect: A type of arthropod that as an adult will have six segmented legs and three body parts: a head, thorax and abdomen. There are hundreds of thousands of insects, which include bees, beetles, flies and moths.
orca: The largest species of dolphin. The name of this black-and-white marine mammal, Orcinus orca, means killer whale.
paleobiologist: A scientist who studies organisms that lived in ancient times — especially geologically ancient periods, such as the dinosaur era.
paleontologist: A scientist who specializes in studying fossils, the remains of ancient organisms.
predator: (adjective: predatory) A creature that preys on other animals for most or all of its food.
prey: (n.) Animal species eaten by others. (v.) To attack and eat another species.
sea: An ocean (or region that is part of an ocean). Unlike lakes and streams, seawater — or ocean water — is salty.
trilobite: An extinct group of arthropods that were related to modern-day insects.