fossil noun The preserved remains or traces of an ancient plant or animal, typically found in rock. Paleontologists discovered a dinosaur fossil embedded deep within the cliffside rock. + extinct adjective No longer existing, especially describing a species that has died out completely. The dodo became extinct within a century of humans arriving on its island. + herbivore noun An animal that feeds mainly or entirely on plants. Deer are herbivores that graze on grasses, leaves, and young shoots. + carnivore noun An animal that feeds mainly or entirely on the flesh of other animals. Lions are carnivores that hunt in coordinated groups across the savanna. + omnivore noun An animal or person that eats both plants and animals. Bears are omnivores, eating everything from berries to fish and small mammals. + predator noun An animal that hunts and kills other animals for food. The lion is a top predator that hunts across the open savanna. + prey noun An animal that is hunted and killed by another animal for food. The zebra became easy prey once it strayed from the herd. + reptile noun A cold-blooded animal with scaly skin that typically lays eggs, such as a snake, lizard, or turtle. The zoo's reptile house features snakes, lizards, and a giant tortoise. + skeleton noun The internal framework of bones that supports and protects the body of a vertebrate. The museum displayed a full dinosaur skeleton in the main hall. + excavate verb To dig into the ground to expose or remove something, often as part of construction or archaeology. Archaeologists spent months excavating the ancient temple buried beneath the desert sand. + paleontologist noun A scientist who studies fossils to understand ancient life and the history of the Earth. The paleontologist carefully brushed dirt away from the dinosaur bones buried in the cliffside. + Jurassic proper noun The geologic period lasting from about 201 to 145 million years ago, known for dominant dinosaurs. Fossils from the Jurassic period show enormous long-necked dinosaurs roaming ancient forests. + Cretaceous proper noun The geologic period from about 145 to 66 million years ago, the last period of the Mesozoic Era, ending with the extinction of the dinosaurs. Fossils from the Cretaceous period reveal a wide variety of flowering plants. + Triassic proper noun The geological period from about 252 to 201 million years ago, the first period of the Mesozoic era. The earliest dinosaurs appeared during the Triassic period. + era noun A long and distinct period of time marked by particular events, developments, or characteristics. The invention of the printing press marked the beginning of a new era in communication. + species noun A group of living organisms that share common characteristics and can interbreed to produce fertile offspring. Scientists discovered a new species of frog deep in the rainforest. + habitat noun The place and conditions in which an organism normally lives. The hedgerow provides habitat for nesting birds. + camouflage noun Coloring or patterns that help a person, animal, or object blend into its surroundings. The soldier's camouflage made him nearly invisible against the dense brush. + talon noun A sharp, curved claw, especially one belonging to a bird of prey. The eagle sank its talons into the fish the instant it broke the water's surface. + claw noun A sharp, curved nail on the foot of an animal, used for gripping, digging, or attacking. The cat extended its claws as it batted playfully at the toy. + fang noun A long, sharp, pointed tooth used by an animal to bite, grip, or inject venom. The snake sank its fangs into the mouse before swallowing it whole. + scale noun The relative size or extent of something, especially in comparison to something else. The scale of the disaster became clear only after aerial footage was released. + tail noun The rear part of an animal's body, often long and flexible, extending beyond its trunk. The dog wagged its tail excitedly the moment it saw its owner at the door. + giant noun An imaginary or legendary being of human form but of enormous size and strength. In the old tale, a giant guarded the castle at the top of the beanstalk. + prehistoric adjective Relating to the very distant past, before humans began keeping written historical records. The museum displayed the bones of a prehistoric creature that lived millions of years ago. + extinction noun The complete disappearance of a species or type of thing from existence. Habitat loss is pushing many rainforest species toward extinction. + sediment noun Solid material, such as sand, silt, or mud, that settles at the bottom of a liquid. A thin layer of sediment had built up at the bottom of the old fish tank. + amber noun A hard, translucent fossilized tree resin, typically yellowish-orange, used in jewelry. The museum displayed a piece of amber with an insect trapped inside it. + bone noun One of the hard, rigid structures that form the skeleton of a vertebrate animal. The X-ray showed a small fracture in the bone just above her wrist. + evolve verb To develop gradually over time, especially through a natural process of change. The company's product evolved from a simple app into a full software platform. +