Time

Fossils and the Scientific Process

Life through Time

Evolutionary Milestones

Extinctions

Fossil Activities

Fossils Glossary

Further Research

Link to Dinosaur Walk

Link to Prehistoric Life

Fossils Glossary

Scientists who work with fossils (palaeontologists) use a lot of special terms which usually refer to groups of fossil plants or animals. This glossary lists some of the main ones you might encounter when reading books about dinosaurs and other fossils.

Ammonoids: A group of cephalopod molluscs related to the living pearly nautilus. Ammonoids had an external shell divided internally into chambers which were used to control flotation. They became extinct at the end of the Cretaceous Period.
Angiosperms: Flowering plants (cf. Gymnosperms)
Araucarians: Genus of tall coniferous trees with sharply pointed, tough leaves. Includes the bunya bunya of Queensland, the Norfolk Island pine and the monkey puzzle tree of southern South America.
Archaeopteryx: The oldest known bird. Archaeopteryx had feathers, scales on its neck and feet, teeth, and claws on all four limbs. It is considered to be a descendant of early dinosaurs.
Arthropods: A very large, diverse group of invertebrates with hard external skeleton and jointed-limbs. Includes crustaceans, spiders, and insects.
Belemnites: A group of cephalopods with an internal, bullet-shaped shell; related to squids, octopuses and cuttlefish. Belemnites became extinct in the early Cainozoic.
Bivalves: A large group (class) of marine and freshwater molluscs with a shell in two parts hinged together (eg. mussels, clams, oysters).
Brachiopods: Also known as lamp shells. A group (phylum) of marine invertebrates with a two-valved shell. During adult life, many brachiopods are attached to the sea-bed by a stalk or by one shell. They were very abundant in the oceans of the Palaeozoic Era.
Bryozoans: Also known as moss-animals. A group of small, aquatic colonial animals. Many possess well-developed calcareous skeletons that are commonly fan-shaped, stick-like or mound-like but may also be encrusting. Sometimes form significant components of reefs.
Cephalopods: A group (class) of marine molluscs that includes nautiloids, squids, octopuses, cuttlefish, and the extinct ammonoids and belemnites
Ceratopsians: Horned, ornithischian (bird-hipped) dinosaurs, such as Triceratops. Ceratopsians had beak-like jaws, a large, bony frill which protected the neck and shoulders, and several forward-projecting horns.
Chondrichthyes: Cartilaginous fish, having cartilage rather than bone within their bodies (sharks and rays).
Chordates: Animals that possess a rod of flexible tissue (notochord); includes vertebrates (fish, amphibians, reptiles, birds and mammals).
Club mosses: Evergreen plants densely covered with simple spirally arranged leaves and reproducing by spores. Living club mosses are small plants but in the Carboniferous Period they reached the size of large trees.
Coelacanths: A group of lobe-finned fish, known mostly from fossils but still existing in the ocean off South Africa.
Continental Drift: The widely accepted view that the continents of the Earth are slowly drifting across the surface of the globe.
Correlation: The process of establishing the equivalence in age of two rock sequences in different areas by locating identical fossils in each sequence.
Crinoids: Also known as feather-stars and sea-lilies. Crinoids are a group (class) of echinoderms with many movable arms and often attached to the sea-floor by a long stalk. They have a long fossil history extending back to the Cambrian Period.
Crustaceans: A diverse group of arthropods that includes crabs, lobsters, shrimps and woodlice (slaters).
Cycads: Plants with leaves and habit similar to those of palm trees. Cycads were very plentiful in the Mesozoic Era.
Diprotodontids: A group of large rhinoceros-sized marsupials which existed in Australia until perhaps 20,000 years ago.
Echinoderms: A group (phylum) of marine invertebrates with skeletal plates in the skin and often five axes of symmetry; eg. sea urchins, sea cucumbers, sea stars and sea lilies.
Echinoids: Group (class) of echinoderms including sea urchins, heart urchins, sand dollars, etc. They are spiny and globular to disc-like in shape.
Eurypterids: Extinct water scorpions, up to two metres in length, making them the largest arthropods that have ever lived. These were amongst the first invertebrates to move from the sea into freshwater, and possibly for brief periods onto land.
Foraminifera: Foraminifera are a type of protozoa, mostly marine, with a shell of lime, silica or agglutinated sand grains. Their shells form an important part of chalk, and of many deep-sea oozes. Fossil foraminiferans are usually less than 1 mm across, although some were up to 100 mm in diameter.
Gastropods: A group (class) of aquatic and terrestrial molluscs including slugs and snails.
Genera: Plural of genus*one of the kinds of group used in classifying organisms. A genus consists of a number of similar species.
Ginkgoes: A group of trees that flourished during the Mesozoic Era; the maidenhair tree is the only living representative.
Glossopteris: Ancient seed-fern whose fossils are found in coal deposits of Permian age in southern continents, thereby providing evidence of the existence of the super-continent Gondwana.
Gondwana: A super-continent which existed in the southern part of the globe until about 200 million years ago, when it began to break into its constituent parts: Africa, Madagascar, India, South America, Antarctica and Australia.
Graptolites: Small marine animals that lived in twig-like colonies; extinct since the Carboniferous Period; classified as hemichordates.
Gymnosperms: 'Naked-seed plants', such as the modern pine tree.
Hadrosaurs: A major group of two-legged, herbivorous ornithischians (or 'bird-hipped' dinosaurs), many of which had crests; also known as 'duck-billed' dinosaurs.
Hemichordates: Small group of marine animals with gills and a rod-like stiffening structure (notochord) in the body; includes worm-like burrowing forms and sedentary forms, some of which are encrusting.
Hypsilophodontids: A major group of two-legged, herbivorous ornithischians (or 'bird-hipped' dinosaurs). Ancestral group that gave rise to the hadrosaurs.
Ichthyosaurs: A group of marine reptiles with superficial resemblance to dolphins but unrelated to them. They became extinct at the same time as the dinosaurs.
Invertebrates: Collective term for all animals which are not vertebrates; includes protozoans, sponges, jelly fish, worms, snails, insects, crabs, sea stars, etc.
Isotope: One of two or more varieties of a chemical element whose atoms have the same number of protons and electrons but different numbers of neutrons.
Labyrinthodonts: The main group of fossil amphibians, ranging in length from a few centimetres to several metres. Contains forms closely related to certain fish and others transitional to reptiles.
Lepospondyls: A group of small Palaeozoic amphibians.
Mammal-like reptiles: The extinct reptilian ancestors of mammals; also known as synapsids.
Marsupials: Mammals that give birth to young at a very immature stage, e.g. kangaroos. While many marsupials have pouches, not all do.
Megafauna: The large animals (mammals and flightless birds) that existed in the Quaternary and, in many cases, became extinct at the end of the last ice age (about 10,000 years ago).
Mesosaurus: Ancient reptiles whose fossils are found in Brazil and South Africa, thereby providing evidence of continental drift. They were adapted to life in fresh water, lightly built, and up to one metre in length.
Molluscs: Large group (phylum) of mostly aquatic invertebrates including mussels, snails, octopuses, etc.; soft bodied, often with a hard shell.
Monotremes: Egg-laying mammals. The only living monotremes are the platypus and the echidna.
Mosasaurs: A group of marine lizards which became extinct at the same time as the dinosaurs. Similar to pliosaurs.
Nautiloids: A group of cephalopod molluscs with an external, chambered shell that is either straight or coiled. Nautiloids were very diverse in the past but only a single genus, Nautilus (the pearly nautilus), survives at the present day.
Omnivorous: Eating both meat and vegetable matter as food.
Ornithischians: The 'bird-hipped' dinosaurs, one of the two main groups of dinosaurs (cf. saurischians). The ornithischians, which were all herbivores, included two-legged forms such as Iguanadon, the hypsilophodontids and the hadrosaurs or duck-billed dinosaurs; and quadrupedal forms such as Centrosaurus and Talarurus.
Palaeontology: The study of life in the geological past.
Pelycosaurs: The more primitive of the two groups of (extinct) synapsids or mammal-like reptiles (cf. therapsids). Several sported large, sail-like dorsal fins.
Phylum: One of the major groups used in classifying animals, coming below kingdom and comprising one or more classes. Plural is phyla.
Placentals: Mammals whose young are nourished before birth by a highly organised placenta, and are then born at a relatively developed stage (cf. marsupials). Most mammals are placentals.
Plate tectonics: The theory that the crust of the Earth is divided into about 15 plates which are slowly drifting across the surface of the globe, driven by convection currents within the mantle below.
Plesiosaurs: A group of aquatic reptiles with long necks and small heads which became extinct at the same time as the dinosaurs. Some grew up to 15 metres in length.
Pliosaurs: A group of marine reptiles with very large heads which became extinct at the same time as the dinosaurs.
Protoceratopsians: The immediate ancestors of the horned dinosaurs, such as Protoceratops. Protoceratopsians themselves lacked horns.
Protozoans: A major group (phylum or subkingdom) of single-celled animals (e.g. Amoeba).
Pteranodons: A group of pterosaurs (flying reptiles) having a long beak and a large counter-weight on the back of the head. They became extinct long before the dinosaurs.
Pterodactyls: A type of pterosaur (extinct flying reptiles) that became extinct at the same time as the dinosaurs. Characterised by the lack of a tail.
Pterosaurs: Any of a group of extinct flying reptiles with large bat-like wings, including pterodactyls and rhamphorhynchoids. Their mode of life probably involved swooping over the sea to catch fish. They became extinct at the same time as the dinosaurs.
Rudistids: An aberrant group of extinct, reef-forming bivalves common in the tropical seas of the Cretaceous Period.
Rugose and tabulate corals: Groups (orders) of stony corals that became extinct at the end of the Palaeozoic Era.
Saurischians: The 'lizard-hipped' dinosaurs, which were one of the two main groups of dinosaurs (cf. ornithischians). The saurischians are, in turn, divided into the theropods (which included all the carnivores) and the sauropods (which were the huge, long-necked dinosaurs).
Sauropods: A major group of saurischian (or 'lizard-hipped' dinosaurs). (The other major group of saurischians was the theropods.) Apart from the most primitive types, sauropods were massive, four-legged, long-necked herbivorous dinosaurs like Apatosaurus and Mamenschisaurus.
Scleractinian corals: An order of solitary or, more commonly, colonial corals that first appeared in the Triassic Period and form coral reefs at the present day.
Seed-ferns: Terrestrial plants in which the seeds or seed-like structures, and sporangia, were situated on the foliage rather than borne in cones
Stromatolites: Trace fossils of bacterial communities, occurring as dome or column like structures; may be very ancient, but existing as living communities on the West Australian coast.
Synapsids: An extinct group of reptiles having one opening in the back of their skulls; also known as mammal-like reptiles.
Thecodonts: Reptilian ancestor of the dinosaurs, pterosaurs, and crocodiles.
Therapsids: The more advanced of the two groups of (extinct) mammal-like reptiles that eventually gave rise to the mammals.
Theropods: The two-legged, 'beast-footed' dinosaurs; a major division of the saurischian (or 'lizard-hipped') dinosaurs. All of the carnivores (e.g. Tyrannosaurus) were theropods (cf. sauropods).
Trilobites: Ancient marine arthropods, abundant in the Early and Middle Palaeozoic but extinct since the Permian Period. Their name is derived from the three lobes running the length of the body. They had paired, gill-bearing limbs and compound eyes. Sizes ranged from a few millimetres to about 90 cm.
Vertebrates: A major group of chordates, with a skull surrounding a well-developed brain, and a skeleton of cartilage or bone. Includes the fish, amphibians, reptiles, birds and mammals.