Dino dictionary 📖

Tricky words from around DinoVerse. Dotted-underlined words on other pages link here.

Ankylosaur: Ankylosaurs were armoured, tank-like dinosaurs, and some had a heavy club on the end of the tail.; Thyreophoran ornithischians covered in osteoderms. Ankylosaurids had tail clubs, while nodosaurids lacked clubs but often had large shoulder spikes.
Apex predator: An apex predator is a hunter at the very top of the food chain that nothing else hunts.; A predator with no natural predators of its own as an adult, sitting at the top of its food web. Tyrannosaurus in Late Cretaceous North America and large pliosaurs in Jurassic seas are examples.
Archosaur: Archosaurs are the reptile family that includes crocodiles, dinosaurs, birds and pterosaurs.; The "ruling reptiles", a clade that split in the Triassic into a crocodile line and a bird line; the bird line includes pterosaurs and dinosaurs. Crocodilians and birds are the living archosaurs.
Asteroid: An asteroid is a big space rock, and one about 10 km wide crashed into Earth and helped wipe out the big dinosaurs.; A rocky body orbiting the Sun. The impact of an asteroid roughly 10 km across formed the Chicxulub crater in Mexico 66 million years ago; its dust, soot and gases blocked sunlight and collapsed food chains, alongside huge volcanic eruptions in India.
Beak: A beak is a hard, toothless mouth edge, like a bird's, used for snipping or pecking.; A jaw edge covered by a keratin sheath (the rhamphotheca). Ornithischian dinosaurs such as ceratopsians and hadrosaurs used beaks to crop plants, and several theropod lines, including birds, evolved beaks independently.
Carnivore: A carnivore is an animal that eats meat.; An animal whose diet is mainly other animals. Clues in fossils include blade-like serrated teeth, sharp claws, bite marks on prey bones and bone fragments in coprolites.
Ceratopsian: Ceratopsians were beaked plant-eaters with bony frills, and many had horns, like Triceratops.; Marginocephalian ornithischians identified by the rostral bone, which forms the upper beak. Early forms were small and two-legged; later ceratopsids carried large frills and horns.
Clade: A clade is a family group on the tree of life: one ancestor plus every animal that came from it.; A group made up of a common ancestor and all of its descendants. Because birds descend from theropods, any clade containing all dinosaurs must also contain birds.
Coprolite: A coprolite is fossil poo, and it can show what an animal ate.; Fossilised dung, a type of trace fossil. Coprolites can contain bone fragments, plant tissue or fish scales, giving direct evidence of diet; a large tyrannosaur coprolite from Canada was packed with crushed bone.
Crest: A crest is a bony shape on top of an animal's head, used for showing off or making sounds.; A bony or soft-tissue structure on the head. In hadrosaurs like Parasaurolophus the crest held looping nasal passages that may have worked as a resonating chamber; in pterosaurs and many theropods crests were probably display signals.
Cretaceous: The Cretaceous was the last part of the dinosaur age, when T. rex and Triceratops lived and the first flowers bloomed.; The last and longest period of the Mesozoic, about 145 to 66 million years ago, named after the Latin word for chalk. Flowering plants spread, and it closed with the asteroid impact and mass extinction that ended the non-bird dinosaurs.
Dinosaur: Dinosaurs were a big family of reptiles that walked with their legs straight under their bodies, and birds are the dinosaurs still alive today.; Dinosauria is the clade containing the last common ancestor of birds and Triceratops and all its descendants. Dinosaurs are recognised by features such as an open hip socket and legs held directly beneath the body; pterosaurs, plesiosaurs and mosasaurs fall outside the group.
Extinction: When a kind of animal or plant is extinct, there are none of them left alive anywhere.; The permanent loss of a species or larger group. Extinction happens all the time at a low "background" rate; most species that have ever lived are now extinct.
Food chain: A food chain shows who eats whom, starting with plants and ending with the biggest hunters.; A linear sequence of feeding links from producers (plants) to consumers; a food web shows the many overlapping chains in an ecosystem. When the end-Cretaceous impact blocked sunlight, failing plant growth collapsed whole food webs.
Fossil: A fossil is what is left of a very old plant or animal, like a bone, tooth or footprint, saved in rock.; Any preserved remains or trace of an organism more than about 10,000 years old. Body fossils (bones, teeth, shells) usually form when minerals slowly fill or replace the original tissue; trace fossils record behaviour, such as footprints, burrows and coprolites.
Frill: A frill is a big bony shield sticking out from the back of the head, like on Triceratops.; A backward extension of the parietal and squamosal bones of the skull in ceratopsians. Frill shapes vary widely between species and probably served mainly for display and recognition.
Gastrolith: A gastrolith is a stone that an animal swallows, which may help mash up food in its tummy.; A stone held in the digestive tract. Birds and crocodiles use them, and they occur with some dinosaurs such as Psittacosaurus, but studies suggest sauropods did not rely on them as a grinding mill as once thought.
Hadrosaur: Hadrosaurs were duck-billed dinosaurs with flat snouts and lots of teeth, and some had fancy head crests.; Late Cretaceous ornithopods with a broad, toothless bill and rows of stacked grinding teeth. Some, like Parasaurolophus, had hollow crests that may have amplified calls.
Herbivore: A herbivore is an animal that eats plants.; An animal whose diet is mainly plant material. Herbivorous dinosaurs show adaptations such as beaks, grinding tooth batteries, large guts and, in some cases, swallowed gastroliths.
Ichthyosaur: Ichthyosaurs were dolphin-shaped sea reptiles with huge eyes that gave birth to live babies.; Marine reptiles from the Early Triassic to about 90 million years ago with a streamlined body, tail fluke and dorsal fin. Their dolphin-like shape is a famous example of convergent evolution.
Jurassic: The Jurassic was the middle part of the dinosaur age, when giant long-necked dinosaurs roamed.; The middle period of the Mesozoic, about 201 to 145 million years ago, named after the Jura Mountains on the France–Switzerland border. Pangaea was breaking apart, sauropods reached giant sizes and the first birds, such as Archaeopteryx, appeared.
Laramidia: Laramidia was a long island-continent on the western side of North America where T. rex and Triceratops lived.; The western landmass of North America during much of the Late Cretaceous, separated from eastern Appalachia by the Western Interior Seaway. Many famous fossils from Montana, Alberta and Utah come from Laramidia.
Mass extinction: A mass extinction is when lots and lots of different living things die out at about the same time.; A geologically short interval in which a large share of species worldwide disappear. Five major ones are recognised; the end-Permian (about 252 million years ago) was the worst, and the end-Cretaceous (66 million years ago) ended the non-bird dinosaurs.
Mesozoic: The Mesozoic is the long stretch of time when dinosaurs lived, sometimes called the Age of Reptiles.; The geological era from about 252 to 66 million years ago, divided into the Triassic, Jurassic and Cretaceous periods. It begins after the end-Permian mass extinction and ends with the end-Cretaceous extinction.
Million years ago: "Million years ago" (or mya) tells you how long ago something happened, and dinosaurs lived many millions of years ago.; A unit used to give geological dates, abbreviated mya or Ma. For example, the end-Cretaceous extinction happened about 66 mya.
Mosasaur: Mosasaurs were giant sea lizards with flippers and a tail fin, related to today's lizards and snakes.; Late Cretaceous marine squamates that became top ocean predators about 98 to 66 million years ago. They had a fluked tail and extra teeth on the roof of the mouth.
Museum cast: A museum cast is a copy of a real fossil made from a mould, so lots of museums can show the same skeleton.; A replica made by moulding original bones and filling the mould with plaster, resin or fibreglass. Casts are lighter and safer to mount, while the original fossils are kept in collections for study; good museums label which parts are real.
Omnivore: An omnivore is an animal that eats both plants and meat.; An animal with a mixed diet of plant and animal food. Some theropods, such as ornithomimids and oviraptorosaurs, are thought to have been omnivores.
Ornithopod: Ornithopods were beaked plant-eating dinosaurs, like Iguanodon and the duck-billed dinosaurs.; A clade of ornithischian dinosaurs with a beak and complex chewing teeth. It includes Iguanodon and the hadrosaurs, whose dental batteries held hundreds of teeth.
Osteoderm: An osteoderm is a piece of bone that grows in the skin, making armour like a crocodile's back.; A bony deposit formed within the skin. Ankylosaurs were covered in osteoderms of many shapes and sizes, and crocodilians and armadillos have them today.
Pachycephalosaur: Pachycephalosaurs were two-legged dinosaurs with thick, round domes on top of their heads.; Marginocephalian ornithischians, mostly from the Late Cretaceous, with thickened skull roofs. Healed injuries on many domes suggest they were used in combat, though the details are still debated.
Palaeontologist: A palaeontologist is a scientist who digs up and studies fossils to learn about life long ago.; A scientist who studies the history of life using fossils, combining field collecting with anatomy, geology, statistics and imaging such as CT scanning. "Palaeontologist" is the British spelling; "paleontologist" is the American one.
Pangaea: Pangaea was one giant piece of land made of all the continents joined together when the first dinosaurs lived.; The supercontinent that formed by the late Palaeozoic and began breaking apart in the Early Jurassic, about 200 million years ago. Its break-up into northern Laurasia and southern Gondwana separated dinosaur faunas over time.
Permian: The Permian was the time just before the dinosaurs, when sail-backed animals like Dimetrodon lived.; The last period of the Palaeozoic Era, about 299 to 252 million years ago. It was dominated on land by synapsids such as Dimetrodon and ended with the largest mass extinction in Earth's history.
Piscivore: A piscivore is an animal that mostly eats fish.; An animal specialised for eating fish, often with long jaws and cone-shaped teeth. Spinosaurus, Baryonyx and many marine reptiles are interpreted as piscivores.
Plesiosaur: Plesiosaurs were sea reptiles with four big flippers, and many had very long necks.; Sauropterygian marine reptiles that swam with four wing-like flippers, from the latest Triassic to the end of the Cretaceous. Short-necked, big-headed forms are called pliosaurs.
Predator: A predator is an animal that hunts and eats other animals.; An organism that kills and eats other organisms. Evidence for predatory behaviour in fossils includes healed bite wounds on living prey and fossils preserved mid-fight, such as the Mongolian "Fighting Dinosaurs".
Prey: Prey is an animal that gets hunted and eaten by another animal.; An organism hunted and killed by a predator. Defences such as armour, horns, tail clubs, speed and herding are often read as adaptations of prey animals.
Pterosaur: Pterosaurs were flying reptiles with skin wings that lived with the dinosaurs but were not dinosaurs.; Flying archosaurs whose wing membrane stretched from a greatly lengthened fourth finger. They are close relatives of dinosaurs but sit outside Dinosauria; examples include Pteranodon and Quetzalcoatlus.
Radiometric dating: Radiometric dating is how scientists use tiny clocks inside some rocks to work out how old they are.; A method that measures the decay of radioactive isotopes, such as uranium turning into lead or potassium turning into argon, usually in volcanic ash layers above and below fossils. Carbon-14 cannot date dinosaurs because it is only useful for roughly the last 50,000 years.
Reptile: Reptiles are animals like lizards, snakes, turtles and crocodiles, and dinosaurs were reptiles too.; In modern classification Reptilia is the clade of amniotes that includes turtles, lizards, snakes, crocodilians, dinosaurs and birds. Synapsids, including mammals and Dimetrodon, are not reptiles.
Sauropod: Sauropods were huge plant-eating dinosaurs with very long necks and tails, like Diplodocus.; Large four-legged sauropodomorphs with air-filled vertebrae, pillar-like limbs and very long necks. Titanosaurs such as Argentinosaurus were the largest land animals known.
Sauropodomorph: Sauropodomorphs are the long-necked dinosaur family, including the giant sauropods and their smaller early relatives.; The saurischian clade that includes sauropods and their earlier, often two-legged relatives such as Plateosaurus, once called "prosauropods". Long necks and small heads appeared early in the group's history.
Scavenger: A scavenger is an animal that eats animals that are already dead.; An animal that feeds on carcasses it did not kill. Most large predators, living and extinct, scavenge when they can; the old idea that T. rex was only a scavenger is not supported.
Serrated: Serrated means having a row of tiny bumps along an edge, like a bread knife.; Bearing small saw-like points (denticles) along a cutting edge. Serrated teeth, typical of many theropods, grip and slice flesh efficiently, and denticle shape can help identify isolated teeth.
Stegosaur: Stegosaurs were plant-eating dinosaurs with plates on their backs and spikes on their tails.; Thyreophoran ornithischians of the Middle Jurassic to Early Cretaceous with two rows of plates or spines along the back and a spiked tail. Stegosaurus and Kentrosaurus are well-known examples.
Synapsid: Synapsids are the animal family that mammals belong to, and early ones like Dimetrodon lived before the dinosaurs.; Amniotes with a single skull opening behind each eye. They include early forms such as Dimetrodon, the therapsids and cynodonts, and all mammals, making Dimetrodon closer to humans than to dinosaurs.
Thagomizer: A thagomizer is the group of sharp spikes on the end of a Stegosaurus tail.; An informal name for the arrangement of tail spikes in stegosaurs, borrowed from a 1982 Far Side cartoon by Gary Larson. A puncture wound in an Allosaurus tail bone shows these spikes were used in defence.
Theropod: Theropods were two-legged dinosaurs, mostly meat-eaters, like T. rex, and birds are theropods too.; A clade of saurischian dinosaurs with hollow bones, a wishbone and three main weight-bearing toes. It includes Allosaurus, Tyrannosaurus and Velociraptor, and birds are its living members.
Triassic: The Triassic was the first part of the dinosaur age, when the very first dinosaurs appeared.; The first period of the Mesozoic, about 252 to 201 million years ago. Dinosaurs, pterosaurs and early mammal relatives all appeared during the Late Triassic, on the supercontinent Pangaea.
Western Interior Seaway: The Western Interior Seaway was a long, shallow sea that once split North America in two.; A shallow inland sea that stretched from the Arctic to the Gulf of Mexico during much of the Cretaceous, dividing Laramidia from Appalachia. Its rocks preserve mosasaurs, plesiosaurs, Pteranodon and huge numbers of marine fossils in places like Kansas.