Adaptation A feature of an animal that evolved in response to its environment or way or life. The long neck of a giraffe, for instance, is an adaptation that helps it reach treetops.
Algae Primitive plants and plant-like organisms that grow in wet conditions.
Amber The fossil form of a sticky resin made by certain trees. Perfectly preserved insects and other organisms have been found in amber.
Ammonites Prehistoric sea creatures with coiled, chambered shells. Ammonites were relatives of octopuses and squids.
Amphibian A type of cold-blooded vertebrate, such as frog or newt. Most amphibians develop from larvae that live in water and breathe through gills, becoming land-dwelling adults that breathe air through lungs.
Ancestor An animal or plant species from which a more recent species has evolved.
Angiosperms A scientific term for flowering plants. This group includes broad-leaved trees and grasses.
Ankylosaurs Four-legged, armoured, plant-eating dinosaurs with bony plates that covered the neck, shoulders, and back.
Archosaurs A major group of reptiles that originated in the Triassic Period. It includes dinosaurs, pterosaurs, and crocodylomorphs.
Arthropods Invertebrates with segmented bodies and a hard outer covering (exoskeleton). Extinct arthropods include trilobites and eurypterids. Living ones include insects and spiders.
Aurochs An extinct variety of wild cattle that was the ancestor of modern cattle.
Australopithecus A prehistoric member of the human family that may be a direct ancestor of modern humans. Australopithecus looked like a chimpanzee but walked upright like a human.
Bivalves Aquatic animals such as clams and oysters that live in a hinged shell. The two halves of the shell are usually mirror images of each other.
Bony fish (Osteichthyans) Fish with a skeleton made of bone. Some fish, such as sharks, have a skeleton made of cartilage rather than bone and are classed as cartilaginous fish.
Burgess Shale Formation A site in British Columbia, Canada, where many important Cambrian fossils were discovered. Among the 130 species identified are sponges, jellyfish, worms, and arthropods.
Cambrian The first period of the Palaeozoic Era, from 542 to 488 million years ago. This was when most of the main invertebrate groups appeared in the fossil record.
Camouflage Colours or patterns on an animal’s skin or fur that help it to blend with its surroundings and hide.
Carboniferous The fifth period of the Palaeozoic Era, from 359 to 299 million years ago. During this period, forests covered the land and were inhabited by insects and four-legged vertebrates (tetrapods), including the first amphibians and the first reptiles.
Carnivore An animal that eats meat. The term carnivore can also refer to a specific family of mammals (the order Carnivora).
Cartilage A firm, rubber-like tissue that is part of the skeleton of vertebrates. In fish such as sharks, the entire skeleton is made of cartilage.
Cephalopod Sea creatures with big eyes and a well-developed head surrounded by a ring of tentacles. Examples include octopuses, squid, cuttlefish, and ammonites.
Ceratopsians Two-legged and four-legged, plant-eating dinosaurs with a deep beak and a bony frill at the rear of the skull. They include the horned dinosaurs.
Chelicerate A type of invertebrate with special mouthparts called chelicerae that are used as pincers or fangs. Modern examples include spiders and scorpions.
Cold-blooded An animal is described as cold-blooded if its body temperature rises and falls along with the outside temperature. Animals that maintain a constant body temperature are described as warm-blooded.
Cretaceous The last period of the Mesozoic Era, from 145 to 65 million years ago.
Crinoids (sea lilies) Plant-shaped sea creatures with feathery arms that live anchored to the sea floor by long stalks. They are related to starfish and sea urchins.
Crocodylomorphs A group of reptiles that includes crocodiles, alligators, and their many extinct relatives. Crocodylomorphs appeared at about the same time as the dinosaurs and were once much more varied than today.
Crustaceans A large and varied group of arthropods, most of which live in water. Living examples include crabs, shrimps, and woodlice.
Cycads Palm-like, seed-bearing plants that are topped by a crown of fern-like leaves. They may be short and shrub-like, or grow as high as 20 m (65 ft).
Descendant An animal or plant species that evolved from an early species (its ancestor).
Devonian period The fourth period of the Palaeozoic Era, from 416 to 350 million years ago. The Devonian is also called the “age of fish”. During this period, tetrapods (fourlegged vertebrates) evolved from fish.
Digit A finger, thumb, or toe.
Dinosaurs A large group of archosaurs with upright limbs. Dinosaurs were the dominant land animals for 160 million years.
DNA Deoxyribonucleic acid, a chemical whose molecules carry genetic instructions from one generation to the next in nearly all organisms. (See Genes.) The complex double-helix structure of DNA was discovered in the 1950s.
Domesticated Bred to be tame. Cows, sheep, and dogs are examples of domestic animals.
Dromaeosaurs A group of bird-like, twolegged, carnivorous dinosaurs. Most grew no longer than 2 m (6 ft). Dromaeosaurs lived in all northern continents.
Echinoderms Marine invertebrates with a hard, chalky skeleton and a five-rayed symmetry. They evolved during the Cambrian Period and include starfish, sea lilies, sea cucumbers, and sea urchins.
Ediacaran biota Fossil organisms named after those found in the Ediacaran Hills of Australia. The sea-dwelling, soft-bodied organisms lived about 550 million years ago and were some of the earliest animals.
Embryo An animal or plant in an early stage of development from an egg or a seed.
Environment The natural surroundings in which an animal or plant lives.
Era A very long unit of time. Eras are divided into shorter units called periods. The Mesozoic Era, for example, is divided into the Triassic, Jurassic, and Cretaceous periods.
Eurypterids (sea scorpions) An extinct group of large arthropods related to modern scorpions. Eurypterids lived in the sea and freshwater habitats during the Palaeozoic Era. Some grew more than 2 m (6 ft 6 in) long.
Evolution The gradual change of animal or plant species over long periods of time. Evolution is driven mainly by a process called natural selection.
Excavation Digging out and removing fossils or other objects from the ground.
Exoskeleton An external skeleton. Animals such as crabs have an exoskeleton. In contract, humans have an internal skeleton.
Extinction The dying-out of a plant or animal species. Extinction can happen naturally as a result of competition between species, changes in the environment, or natural disasters (such as an asteroid striking Earth).
Fossil The ancient remains or imprint of a prehistoric organism preserved in rock.
Fossilization The process by which dead organisms turn into fossils. Fossilization often involves replacement of the original organism with rock minerals.
Gastropods A class of invertebrates made up of snails, slugs, and their many aquatic relatives, such as cowries and limpets.
Genes Chemical instructions encoded in the DNA molecule. Genes control the way all organisms grow and develop. They are passed on from parents to their young.
Gondwana A vast prehistoric supercontinent that included South America, Africa, Antarctica, Australia, and India. Gondwana existed from Precambrian times until the Jurassic Period, when these lands began to move apart.
Habitat The place where a plant or animal lives naturally.
Hadrosaurids (duck-billed dinosaurs) A family of plant-eating dinosaur species with duck-like beaks that lived during the Cretaceous Period.
Hagfish (Agnathan) A kind of living jawless fish.
Herbivore An animal that eats plants.
Hominins The family of apes that includes humans and our closest relatives.
Homo erectus A prehistoric member of the human family that lived from 2 million years ago to 100,000 years ago. Homo erectus evolved in Africa but spread to Asia.
Homo sapiens The scientific name for modern human (our own species).
Hybrid The offspring of parents from two different species.
Ichthyosaurs Prehistoric marine reptiles that resembled dolphins or fish.
Iguanodontians Large, plant-eating ornithopod dinosaurs that were common in the Early Cretaceous.
Invertebrates Animals without backbones.
Jawless fish (Agnathans) A class of primitive vertebrates that flourished mainly in Early Palaeozoic times. They include extinct groups and the living hagfish and lampreys.
Jurassic The middle period in the Mesozoic Era, from 200 to 145 million years ago. During the Jurassic Period, dinosaurs dominated the land, the first birds evolved, and mammals began to diversify.
Juvenile A young animal.
Kin Family – individuals that are genetically related.
Lamprey A type of living jawless fish with a round, sucker-like mouth.
Lungfish A type of fish that has both gills and lungs and can breathe in water and air. Lungfish appeared in the Devonian Period.
Mammals Warm-blooded, hairy vertebrates that secrete milk and suckle their young. Living mammals range from tiny shrews to the blue whale (the largest creature ever) and occupy a great variety of habitats. Mammals originated in the Triassic Period.
Marine Belonging to the sea (particularly animals or plants).
Marsupial A type of mammal with a pouch in which the young develop. Living examples include kangaroos and wallabies. Marsupials survive only in Australasia and the Americas.
Mastodons An extinct group of large mammals with trunks, tusks, and thick hair. They were related to the elephants.
Meganeura A kind of giant dragonfly (more correctly called a griffinfly) that lived in the Carboniferous Period. Meganeura was possibly the largest insect ever found on Earth.
Metamorphosis A major change in an organism when it take on its adult form. The change from caterpillar to butterfly is an example of metamorphosis.
Migration A long-distance journey undertaken by animals moving to new homes. Many birds migrate in autumn in order to spend winter in warmer countries.
Molluscs A large group of invertebrate species that includes slugs, snails, clams, octopuses, and squids. Many molluscs produce hard shells that fossilize easily, making mollusc fossils common.
Mosasaurs Giant, sea-dwelling lizards that lived during the Cretaceous Period. They were fierce predators with slender bodies, long snouts, and flipper-like limbs.
Natural selection The natural “weeding out” of animals and plant that drives evolution.
Neanderthal (Homo neanderthalensis) An extinct species of hominin that is very closely related to our own species. Neanderthals lived in Europe and Asia during the last ice age.
Neogene The period of history from 23 million years ago to today. The Neogene Period is divided into the Miocene, Pliocene, Pleistocene, and Holocene epochs.
Nocturnal Awake and active during the night. Nocturnal animals include owls, bats, and cats.
Nothosaurs A group of large, sea-dwelling reptiles that lived in the Triassic Period. Nothosaurs resembled seals and came ashore to breed.
Omnivore An animal that eats both plant and animal food. Examples include pigs, rats, and human beings.
Ordovician The second period in the Palaeozoic Era, from 488 to 444 million years ago. All animals known from this time lived in water.
Ornithischians (bird-hipped dinosaurs) One of two major divisions into which the dinosaur family tree is split (see also Saurischians). Ornithischians were plant eaters with beaked mouths.
Ornithomimids (ostrich dinosaurs) Tall, slender, bird-like dinosaurs that were built like ostriches. They were the fastest animals on land in the Cretaceous Period.
Paleogene The first period in the Cenozoic Era, from 65 to 23 million years ago. The Paleogene is divided into the Paleocene, Eocene, and Oligocene epochs.
Palaeontology The scientific study of fossil plants and animals.
Pampas Treeless, grass-covered plains in South America.
Pangaea A supercontinent that formed at the end of the Palaeozoic Era. Pangaea contained nearly all of Earth’s land and stretched from the North Pole to the South Pole.
Pelvis The part of an animal’s skeleton that forms the hips.
Pelycosaurs A group of large, reptile-like animals that lived before the age of the dinosaurs. Scientists believe that mammals evolved from these creatures.
Period A very long unit of time, lasting million of years. The Jurassic is a period.
Permafrost Permanently frozen ground found in places such as northern Canada and Siberia. Although the surface thaws out and becomes boggy in summer, the deeper soil remains frozen solid.
Permian The last period of the Palaeozoic Era, from 299 to 251 million years ago. The end of the Permian saw a worldwide mass extinction in which most animal species were wiped out.
Placentals Mammals whose unborn young are nourished by a special organ called a placenta. Placental mammals have replaced marsupials in most parts of the world.
Placoderm (armoured fish) A class of prehistoric fish that had body armour formed from plates of bone. They flourished in the Devonian Period.
Plesiosaurs Large, prehistoric marine reptiles that swam with flipper-shaped limbs. Many had enormously long necks and tiny heads. Others (called pliosaurs) had short necks and huge heads with powerful, fang-lined jaws.
Precambrian The great span of time lasting from Earth’s formation 4.6 billion years ago to the start of the Cambrian Period 542 million years ago. For most of the Precambrian, the only forms of life were microscopic, single-celled organisms that lived in water.
Predator An animal that hunts, kills, and eats other animals.|
Preservation Keeping something, for example a fossil, free from harm or decay.
Prey An animal that is hunted, killed, and eaten by a predator.
Primates The group of mammals that includes lemurs, monkeys, apes, and humans.
Primitive At an early stage of evolution.
Pterosaurs Huge flying reptiles that lived during the age of the dinosaurs. The wings of pterosaurs consisted of sheets of skin stretched between the limbs.
Ray-finned fish (Actinopterygii) A major class of fish that includes about 25,000 of today’s fish species and many prehistoric species. Ray-finned fish have fins consisting of skin stretched over a fan of thin bones.
Rays (Batoidea) A group of flat-bodied, cartilaginous fish related to sharks. Examples include stingrays and manta rays.
Reptile A cold-blooded animal with scaly skin that typically lives on land and reproduces by laying eggs. Lizards, snakes, turtles, crocodiles, and dinosaurs are reptiles.
Rodents A group of mostly small mammals that includes mice, rats, squirrels, and porcupines. Rodents have sharp front teeth used for gnawing nuts and seeds.
Saurischians (lizard-hipped dinosaurs) One of the two major divisions into which the dinosaur family tree is split (see also Ornithischians). All meat-eating dinosaurs were saurischians.
Sauropods Gigantic, long-necked, planteating, saurischian dinosaurs. The sauropods included the largest animals ever to walk on Earth.
Savanna Tropical grassland. Savannas are often dotted with trees or patches of woodland.
Scutes Bony plates with a horny covering set in the skin of certain reptiles to protect them from the teeth and claws of enemies.
Sediment Material deposited by wind, water, or ice. Sediments such as sand, silt, and mud build up on the sea floor and are eventually turned into rock (sedimentary rock).
Sedimentary rock The type of rock in which fossils are found.
Silurian The third period in the Palaeozoic Era, from 444 to 416 million years ago.
Skull The head’s bony framework that protects the brain, eyes, ears, and nasal passages.
Species A type of animal of plant. Examples of species include lions, human beings, and apple trees. Individual in a species can breed with each other.
Spinosaurids A family of huge dinosaurs of the Cretaceous Period that had sail-like structures on their backs.
Stegosaurs Four-legged, plant-eating dinosaurs with two rows of tall bony plates and/or spines running down the back.
Supercontinent A prehistoric landmass containing two or more major continental plates. Examples include Gondwana and Pangaea.
Tetrapod A vertebrate with four limbs (arms, legs, or wings). All amphibians, reptiles, mammals, and birds are tetrapods. Snakes are also tetrapods because they evolved from ancestors with four limbs.
Therizinosaurs A group of bizarre-looking dinosaurs that lived in the Cretaceous Period. Therizinosaurs were tall with small heads, stumpy feet, and pot bellies.
Theropods A large branch of the dinosaur family tree made up mostly of predators. Theropods typically had sharp teeth and claws. They ranged from hen-sized creatures to the colossal Tyrannosaurus.
Titanosaurs Very large, four-legged, plant-eating dinosaurs. The titanosaurs were sauropods and included perhaps the largest land animals ever.
Triassic The first period in the Mesozoic Era, from 251 to 200 million years ago. Dinosaurs emerged in the Triassic Period.
Trilobites Prehistoric sea creatures with external skeletons divided lengthwise into three lobes. Variations in the shape and features of trilobite fossils are an accurate indicator of the age of the sedimentary rocks in which they are found.
Vertebrae The linked bones forming the backbone of a vertebrate animal.
Vertebrates Animals with an internal bony or cartilaginous skeleton including a skull and a backbone. Fish, amphibians, reptiles, birds, and mammals are all vertebrates.
Warm-blooded Animals that maintain a constant internal body temperature are described as warm-blooded. Mammals and birds are warm-blooded, whereas fish and reptiles are cold-blooded.
Wingspan The distance from the tip of one wing to the tip of the other when both wings are outstretched.