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an extinct group of cartilaginous fish that first appeared in the Silurian period. Also called "spiny sharks" because they had a shark-like shape and numerous spines on their bodies and fins. Acanthodians were the first jawed vertebrates.
Accretion the gradual addition of new land to old by the deposition of sediment, or by the amalgamation of landmasses.
Adaptive radiation the evolutionary diversification of an ancestral population into several descendant populations, each adapted to a different ecological niche.
Aerobic respiration the process whereby food molecules are oxidised to produce CO2, H2O, and energy (in the form of the molecule ATP). Aerobic respiration requires oxygen and occurs in the mitochondria of all eukaryote cells.
Agnathans the "jawless fishes", a group that includes the modern hagfish and lamphrey. As their name suggests, they have no jaws. The skeleton is cartilaginous and they have no paired pectoral or pelvic fins.
Amino acid one of the molecular building blocks of proteins. A protein is made up of a chain of amino acids in a certain sequence. This sequence of amino acids determines the properties of the protein, and is itself determined by the order of the bases in DNA.
Amniotic egg a shelled egg, with a large yolk and a number of shell membranes, which retains water and allows reptiles, birds, and egg-laying mammals to reproduce on land. Named for the amnion, the innermost shell membrane, which encloses a fluid-filled sac surrounding the developing embryo.
Amoebae any of a number of one-celled aquatic or parasitic protozoans belonging to the genus Amoeba or to related genera. An amoeba has no definite form. Each cell consists of a mass of protoplasm containing one or more nuclei and surrounded by a flexible outer membrane. It moves by means of pseudopods.
Amphibians a class of vertebrates that includes the frogs & toads, newts & salamanders, and the wormlike caecilians, together with a number of extinct subclasses. Amphibians do not have an amniotic egg and usually return to the water to reproduce. They metamorphose from an aquatic larva to the adult form, which has a moist, scale-less skin and is at least partially terrestrial.
Anaerobic an organism, such as a bacterium, that can live in the absence of free (gaseous or dissolved) oxygen.
Angiosperm (Anthophyte): a plant whose ovules are enclosed in an ovary; a flowering plant.
Annelid a member of the group of worms or wormlike animals belonging to the phylum Annelida e.g. earthworms, leeches. Annelids have an elongated, cylindrical, segmented body.
Anoxic describes an environment that lacks oxygen
Anthropic of or relating to humans
Apatite a natural, variously coloured calcium fluoride phosphate, Ca5F(PO4)3, with chlorine, hydroxyl, or carbonate sometimes replacing the fluoride. It is a source of phosphorus for plants and is used in the manufacture of fertilizers.
Arachnid a member of the arthropod class Arachnida e.g. spiders, scorpions, mites, and ticks, characterised by four pairs of segmented legs and a body that is divided into two regions, the cephalothorax and the abdomen. Also called arachnoid.
Arboreal here used to describe those primates, particularly the apes, which spend a large proportion of their time in the trees.
Archetype an original model, or prototype, after which other similar things are patterned.
Archosaurs reptiles of the subclass Archosauria, which includes the dinosaurs, pterosaurs, the modern crocodilians, and birds.
Arthropod any of numerous invertebrate animals of the phylum Arthropoda, including the insects, crustaceans, arachnids, and myriapods. Arthropods are characterised by a chitinous exoskeleton and a segmented body, with paired jointed appendages on many segments. (The name "arthropod" means "jointed foot".)
Articular of or relating to a joint or joints: the articular surfaces of bones.
Artiodactyla the order of hoofed placental mammals that have an even number of functional toes on each foot e.g. pigs, peccaries, hippopotami, and ruminants such as cows and deer.
Asthenosphere the worldwide weak layer below the lithosphere, marked by low seismic wave velocities and high seismic wave attenuation. This is a region of the Earth's mantle which begins at a depth of about 50 to 100 km and extends down to a depth of perhaps 300 to 500 km. The asthenosphere is a soft layer, probably partially molten and may be the site of convection by means of plastic deformation.
Atomic weight the average mass of an atom of an element, usually expressed relative to the mass of carbon 12, which is assigned 12 atomic mass units.
ATP Adenosine TriPhosphate, an energy-carrying molecule. ATP is produced from Adenosine DiPhosphate (ADP) and phosphate during cellular respiration and photo synthesis. The energy released by these processes is stored in the chemical bonds linking a phosphate group to ADP, forming ATP. In turn, ATP releases energy as required by the cell when the bonds are broken: ATP <-> ADP + P
Auditory bulla the bony capsule enclosing the middle (auditory ossicles) and inner (semicircular canals and cochlea) ear of mammals.
Baddelyite a mineral, ZrO2, monoclinic.
Basin analysis involves reconstructing the history of a sedimentary basin, and understanding the processes and mechanisms by which it formed.
Binary fission a method of asexual reproduction that involves the splitting of a parent cell into two approximately equal parts. Bacteria and protozoans reproduce by binary fission.
Biota the combined flora and fauna of a region.
Brachiator a term used to describe primates that habitually move through the trees by swinging from arm to arm beneath the branches. Gibbons (siamangs) and spider monkeys are brachiators.
Brachiopods also known as lamp shells - a phylum of marine bivalved (two shells) invertebrate animals. Brachiopods differ from bivalved molluscs in that they have an internal structure called a lophophore for feeding and gas exchange.
Carbon a naturally abundant non-metallic element that occurs in many inorganic and in all organic compounds. Carbon atoms can bond to each other or to other elements to form an enormous number of chemically, biologically, and commercially important molecules. Elemental carbon is found as graphite and diamond. Economically important carbon compounds include coal, limestone, and petroleum.
Cephalopods a class of molluscs that includes squid, octopus, nautilus and cuttlefish. These animals all have a well-developed head surrounded by prehensile tentacles, a large brain, and complex eyes quite similar to those of vertebrates (an example of convergent evolution). A cephalopod can move rapidly by jet propulsion, squirting water out of its mantle cavity through a siphon.
Charophyte a member of a class of green algae that are considered to be the closest relatives of land plants.
Chitinous made of chitin. This polysaccharide is the main constituent of arthropod exoskeletons and is also found in the cell walls of fungi.
Chordate Phylum a group of organisms with a several physical features in common. At some time in their life, all chordates have: a dorsal stiffening rod (a notochord) for muscles to work against, a dorsal nerve cord, pharyngeal slits (which may become gill slits), and a tail that extends beyond the anus.
Chromosome a structure in the cell nucleus of eukaryotes (the chromosome of prokaryote cells is not bounded by a nuclear membrane). Each chromosome consists of a very long DNA molecule with various proteins, particularly histones, bound to it.
Clade a group of evolutionarily related organisms (species, genera, or families) whose members share homologous features derived from a common ancestor. This means that a clade is monophyletic.
Coevolution the evolution of two or more interdependent species, each adapting to changes in the other. It occurs, for example, between predators and prey and between insects and the flowers that they pollinate.
Columella one of the auditory ossicles, homologous to the stapes ("stirrup") bone of the middle ear in mammals. The columella is the only middle ear bone in reptiles, birds, and frogs.
Comparative biology studies the distribution of biological traits across different organisms (taxa) and the evolutionary origin of these traits.
Concretions rounded masses of mineral matter found in sedimentary rock.
Conifer a member of a group of mostly evergreen gymnosperm trees, many of which have needle-like or scale-like leaves, which have cones as their reproductive structures. Conifers include pines, spruces, and firs. Swamp cypresses are unusual in that they are one of very few gymnosperms that are deciduous.
Continental shelf
That part of the continental edge that is between the shoreline and the continental slope, which has a very gentle slope of 0.1, and is often under the sea.  The edge of the continental shelf is often marked by quite a steep slope.  Continental shelves are considered to be part of the continent to which they are attached as they have a similar rock composition to continental crust.
Continental shield
Shields are the old, eroded part of some continents and often consist of a mixture of crystalline basement rocks with overlying sediments.  They have been eroded flat over time but have not been subjected to extensive tectonic crustal movements, e.g., large parts of Western Australia, southern Africa and eastern Antarctica.
Convergent evolution the independent evolution of similar features in unrelated organisms, as a result of their being exposed to similar selection pressures e.g. dolphins, sharks and ichthyosaurs show convergent evolution in body form. All are fast swimming aquatic predators.
Cranial sutures the fine lines that mark where the separate bony plates that make up a skull have fused together.
Cranium the part of the skull that encloses the brain.
Crinoid an echinoderm belonging to the class Crinoidea, which includes the sea lilies and feather stars. Crinoids have a cup-shaped body, feathery radiating arms, and either a stalk or a clawlike structure attaching them to the substrate.
Cyanobacteria are a group of bacteria (prokaryote organisms) that use the same pigments as green plants to obtain their energy through photosynthesis. They are often referred to as blue-green algae, even though it is now known that they are not related to any of the other algal groups, which are all eukaryotes.
Deccan Traps one of the largest volcanic regions in the world. It covers an area of nearly 500,000 km2 in west-central India in flat-lying basalt lava flows more than 2,000 metres deep. Estimates of the original area covered by the lava flows are as high as 1.5 million km2. The total volume of basalt is estimated to be 512,000 km3. The eruption of the Deccan basalts may have played a role in the extinction of the dinosaurs. Most of the basalt was erupted between 65 and 60 million years ago. Gases released by the eruption may have changed the global climate and thus contributed to the demise of the dinosaurs 65 million years ago.
Dental arcade the shape formed by the tooth sockets in the upper and lower jaws of mammals. Among the primates, monkeys and apes have a rectangular dental arcade, while that of hominins is more rounded.
Diaspora dispersal from a homeland.
Dinosaur any of a number of extinct, often gigantic, carnivorous or herbivorous reptiles belonging to the orders Saurischia and Ornithischia. Dinosaurs lived during the Mesozoic Era; all were terrestrial.
Diurnal used here to describe animals that are active during the daytime rather than at night.
Divaricating to branch into two from each of a series of points. Many of New Zealand's native plants have a divaricating growth habit, particularly but not exclusively in young plants. One hypothesis is that this pattern of growth was an adaptation to grazing by moa.
DNA Deoxyribonucleic acid, a nucleic acid that carries the genetic information in the cell and is capable of self-replication and synthesis of RNA. DNA consists of two long chains of nucleotides twisted into a double helix and joined by hydrogen bonds between the complementary bases adenine and thymine or cytosine and guanine. The sequence of nucleotides determines individual hereditary characteristics.
DNA-derived dates dates for the evolutionary divergence of different groups, based on differences in the DNA code. Known rates of mutation are used to generate these dates, so that two taxa with only a few differences in a DNA sequence diverged more recently than those with many differences between them. Knowing the rate at which mutations accumulate in a particular DNA sequence allows scientists to put approximate dates to these divergences.
Dogma a principle, tenet, or system of principles especially as laid down by the authority of a church.
Domestication animals and plants are described as under domestication, or domesticated, when humans control their living conditions and breeding. This distinguishes domesticated organisms from those that have simply been tamed. Domesticated species can be used for food, fibres, labour, and as pets. Many domesticated species are quite unlike their wild ancestors.
Echinoderm a phylum of exclusively marine, invertebrate animals, nearly all of which have pentaradiate symmetry (5 axes of symmetry) in the adult form and an endoskeleton made of calcium carbonate plates.
Ecological divergence occurs when two populations of a single species move into separate ecological niches. This may be followed by reproductive isolation and the development of two separate species.
Electron a stable subatomic particle in the lepton family having a rest mass of 9.1066 10-28 grams, 1/1836 that of a hydrogen atom, and a negative electric charge.
Endemic prevalent in or peculiar to a particular locality, region, or people: diseases endemic to the tropics.
Endocranial cast a cast of the cranial cavity, formed as the brain decayed and was replaced by fine sediments. Because the brain of a mammal fills the cranium, an endocranial cast gives an indication of the shape of the brain.
Endoskeleton an internal skeleton, usually of bone or cartilage.
Endosymbiosis a symbiotic relationship between two organisms in which one of the two organisms (the endosymbiont) lives inside the body of the other one (the host).
Equilibrium a condition in which all forces or influences are cancelled by others, resulting in a stable, balanced, or unchanging system.
Eukaryotic eukaryotic cells have a distinct nucleus, and are generally larger and have more DNA than prokaryotes (whose DNA is not contained within a nucleus). They also have completely internal membrane-bound organelles. All multicellular organisms are eukaryotes.
Exaptation a "pre-adaptation": a feature that has evolved in one environment, but which turns out to be beneficial in a new, changed environment. The limbs and lungs of lobe-finned fishes, which had evolved before one line of these fish developed into amphibians, are examples of exaptations.
Exoskeletons external skeletons, usually made of calcium carbonate or chitin. Insects and crustaceans have exoskeletons.
Experiment an empirical research method used to examine a hypothesised causal relationship between independent and dependent variables.
Extinction the total disappearance of a species or population
Fauna animals, especially the animals of a particular region or period, considered as a group.
Fast-twitch muscle muscle fibres of this type contract rapidly & often, but usually tire rapidly. They allow rapid, powerful movement.
Foramen magnum the large opening in the base of the skull through which the spinal cord enters the cranial cavity.
Foraminifera a phylum of unicellular protists (or protozoans). These tiny animals have an external calcareous or silicaceous shell. Fine strands of cytoplasm project through pores in these shells, which are the main constituent of chalk.
Fossil the remains (often mineralised) or traces of animals or plants that have been preserved by natural causes in peat, rock, tar, volcanic ash or amber.
Gametophyte one of two generations in a plant's life cycle (the other is the sporophyte). The gametophyte produces the gametes.
Genome the total genetic content contained in a haploid set of chromosomes in eukaryotes, in a single chromosome in bacteria, or in the DNA or RNA of viruses.
Gill arches the arches of tissue found between successive gill slits in jawed fish (and also larval amphibians). A gill arch is made up of the supporting skeletal gill bar and the gill filaments.
Glacial a period during which the climate of the modern temperate regions was polar, and ice covered large portions of the northern hemisphere.
Gondwana (Gondwanaland) ancient continent including Australia, Antarctica, Africa, South America, India south of the Ganges River, and parts of New Zealand. Driven by plate tectonics, Gondwana began to fragment and drift apart during the early Triassic. This fragmentation ended in the late Cretaceous.
Gracile term used to describe the group of australopithecine species with a relatively light, slender build (anamensis, afarensis, africanus) when compared to the "robust" species (robustus, aethiopicus, boisei).
Grand Coupure a mass extinction event triggered by rapid global cooling at the end of the Eocene.
Gymnosperms any seed-bearing plant, such as a cycad or conifer, whose seeds are not enclosed within an ovary.
Haplotype a haploid genotype.
Herbivory describes a lifestyle where food comes from plant sources.
Hermaphrodite a hermaphrodite plant has both stamens and carpels in the same flower. Hermaphroditic animals produce both sperm and ova e.g. earthworms, garden snails.
Hominid a term frequently used to mean a primate of the family Hominidae, of which Homo sapiens is the only extant species. However, using the modern cladistic approach, the other living Great Apes are also placed in the familiy Hominidae and so can also be called hominids. Humans belong to a separate tribe, the Hominini.
Hominins the name given to fossils belonging to the human lineage (see Hominid), distinguishing them from the Hominids (great apes and humans).
Homoiohydric describes plants that can keep their internal water content constant, regardless of the external environment e.g. ferns, conifers and other gymnosperms, flowering plants.
Homology describes the case where structures in several species have a common evolutionary ancestry, even though they may no longer have the same appearance or function e.g. middle ear bones in mammals are homologous to some of the jaw bones in fish.
Homologous refers to structures, behaviours, or DNA sequences than are similar because they have a common evolutionary history.
Homoplasy a cladistic term for the development of similar features due to parallel or convergent evolution.
“Hox” genes or "homeobox-containing genes" are regulatory genes, most of which directly control the development and identity of body parts. They can be regarded as switches that turn the production of other genes on and off in a sequence that controls how embryonic cells differentiate.
Hydrogen a colourless, highly flammable gaseous element, the lightest of all gases and the most abundant element in the universe. Hydrogen is used in the production of synthetic ammonia and methanol, in petroleum refining, in the hydrogenation of organic materials, as a reducing atmosphere, in oxyhydrogen torches, and in rocket fuels.
Hyomandibular bone (or cartilage): a segment of the hyoid arch (see gill arches), which connects the lower jaw with the skull in fish. The hyomandibular is homologous to the columella, or stapes, of the tetrapod ear.
Ice age a glacial period or part of a glacial period; most frequently refers to the last glacial period.
Ichthyosaur an extinct marine reptile belonging to the order Ichthyosauria, which lived from the Triassic to the Cretaceous Period. Ichthyosaurs were superficially similar to dolphins (an example of convergent evolution), with a porpoise-like head and an elongated, toothed snout.
Incus (or "anvil") an anvil-shaped bone between the malleus and the stapes in the mammalian middle ear.
Insect a small arthropod animal of the class Insecta. Insects have an adult stage characterised by three pairs of legs on the thorax, a body divided into head, thorax, and abdomen, and usually two pairs of wings. Insects include the flies, crickets, mosquitoes, beetles, butterflies, and bees.
Interglacial the period of time between successive glaciations.
Invertebrates animals without backbones
Isolation segregation of a group of organisms from related forms in such a manner as to prevent interbreeding
Isotope one of two or more atoms having the same atomic number but different mass numbers.
K-T refers to the Cretaceous-Tertiary (K-T) boundary. It is marked by the presence of a thin layer of iridium-rich clay, found from sites around the world. Dinosaurs, along with many other organisms, became extinct at the K-T boundary. The presence of the iridium layer suggests that this extinction event may have been caused by a collision between an asteroid and Earth, because asteroids are rich in iridium.
Laurasia the Northern landmass formed by the breakup of the supercontinent Pangaea. Laurasia then fragmented into North America, Europe, and Asia under the influence of plate tectonics.
Limestone a bedded sedimentary deposit consisting mainly of calcium carbonate, and often comprises of shells, which generates lime when burned, hence the name. Limestone is the most important and widely distributed of the carbonate rocks.
Linnaean system the basis of the modern taxonomic system. It arranges organisms in nested sets, with Kingdom the highest or most inclusive, and species the lowest.
Lithified As sediments accumulate, various processes start to cement the grains together.  When the grains are cemented, the rock is described as lithified, i.e., it has been changed from loose sediment to rock (Latin = lithos).
Lithosphere the outer, rigid shell of the Earth, situated above the asthenosphere and containing the crust and the uppermost part of the mantle, the continents, and the plates of the Earth.
Lobe-finned refers to a group of fish with fleshy lobes at the base of their fins, and an internal skeletal arrangement homologous to the bones of the upper and lower limbs of tetrapods e.g. coelacanth.
Lophophore a horseshoe-shaped ciliated organ located near the mouth of brachiopods, bryozoans, and phoronids (a phylum of small, worm-like marine animals). The lophophore is used to gather food. 100km.
Lucy the skeletal remains of a female hominid, Australopithecus afarensis, found in Tanzania in 1974 and dated at about 3.2 million years old. At about 40 percent intact, Lucy is the most complete australopithecine skeleton yet discovered.
Lycophyte a member of the phylum that includes the club mosses (class Lycopsida) e.g. Selaginella, Lycopodium.
Magma hot, molten material from the Earth's crust or mantle. Magma forms igneous rock when cooled & solidified.
Malleus (or "hammer"): the hammer-shaped bone that is the outermost of the three small bones in the mammalian middle ear.
Mammal any of various warm-blooded vertebrate animals of the class Mammalia, including humans. Mammals are characterised by a covering of hair on the skin and, in the female, milk-producing mammary glands for nourishing the young.
Marine plankton the collection of small or microscopic organisms, including algae and protozoans, which float or drift in great numbers at or near the surface in fresh or salt water. They are the basis of many aquatic food webs, providing food for fish and other larger organisms.
Marine transgression
A period of time when the sea starts to cover the land, i.e., the sea transgresses over the land surface.  This can be the result of polar ice melting causing the sea level to rise, or it can occur when the land sinks (subsides) and the sea floods over the land.
Marsupials non-placental mammals belonging to the order Marsupialia, including kangaroos, opossums, bandicoots, and wombats. Most modern marsupials are found in Australia and the Americas.
Mass extinction an event in which large numbers of species die out in a very short time (geologically speaking) across the whole of the Earth.
Mass homeothermy describes the phenomenon whereby animals with a very large body size achieve a relatively constant body temperature because of that size. This is because, once a large mass has warmed up, it takes a considerably period of time to cool again.
Metazoans multicellular animals of the subkingdom Metazoa, a division of the kingdom Animalia.
Methane (CH4): an odourless, colourless, flammable gas. Methane is the major constituent of natural gas, which is used as a fuel and is an important source of hydrogen and a wide variety of organic compounds.
Mid-Atlantic ridge
The place along the Atlantic (approximately mid-way between each continent on either side of the Atlantic Ocean) where the crustal plates are spreading apart (see sea-floor spreading).  This spreading system is hotter than the surrounding crust and is more buoyant, hence it sits higher than the surrounding sea floor, forming a ridge.
Mitochondria (chondriosomes) spherical or elongated organelles found in the cytoplasm of all aerobic eukaryotic cells. Each mitochondrion contains its own DNA and many enzymes important for cell metabolism, including those responsible for the conversion of food to usable energy.
Mitochondrial DNA mitochondria contain circular pieces of double-stranded DNA (mDNA). This DNA codes for mitochondrial tRNAs, rRNAs, and proteins. Several copies of the mitochondrial genome are found in each organelle. In humans and other mammals mDNA mutates about 10 times faster than nuclear DNA. This, and the fact that mitochondrial DNA is inherited almost exclusively from the mother, has allowed scientists to use mDNA to estimate the times at which various human populations have diverged.
Mollusc a member of a phylum of unsegmented, invertebrate animals, usually (but not always) with a shell protecting their soft bodies. The phylum Mollusca includes gastropods (e.g. slugs, snails), bivalves (e.g. pipi, scallops), cephalopods (e.g. squid, octopus) and chitons.
Monazite a reddish-brown phosphate mineral containing rare-earth metals (Ce, La, Y, Th), important as a source of cerium and thorium.
Monophyletic a taxonomic group consisting of a single common ancestor and all its descendants.
Monotremes (Monotremata): an order of primitive egg-laying mammals restricted to Australia and New Guinea and consisting of only the platypus and the echidna.
Mosasaur a very large extinct aquatic lizard of the genus Mosasaurus, with modified limbs that served as paddles for swimming. These lizards, thought to have been viviparous and carnivorous, may be early ancestors of the modern monitor lizard.
Multicellular having or consisting of many cells: multicellular organisms.
Multiregional hypothesis the hypothesis that different regional populations of Homo erectus independently gave rise to regional populations of H. sapiens; the alternative to the "out of Africa" hypothesis.
Natural selection this theory states that individuals of a species population are not genetically identical. This means that not all individuals in that population will make an equal contribution (through successful breeding) to the next generation. Those individuals that are best adapted to their local environment will produce more offspring than less well-adapted individuals. The outcome of this differential reproductive success is that the forms of organisms in a population that are best adapted to their local environment increase in frequency relative to less well-adapted forms over a number of generations. At the genetic level, over time there will be a change in the frequency of particular genes. This difference in survival and reproduction is not due to chance.
Neutron an electrically neutral subatomic particle in the baryon family with a mass 1,839 times that of the electron. The neutron is stable when bound in an atomic nucleus. Neutrons and protons together form nearly the entire mass of atomic nuclei.
Non-disjunction occurs when the members of a pair of homologous chromosomes are not separated during meiosis. Non-disjunction may affect a single pair of homologous chromosomes e.g. Down's syndrome, or trisomy 21, is due to non-disjunction of chromosome 21. When it affects the whole chromosome set, the outcome is polyploidy.
Occipital the region of bone that forms the posterior segment of the skull and surrounds the foramen magnum, the opening through which the spinal cord leaves the cranium.
internal structures within a cell, each completely surrounded by a membrane, that have specific functions.
This is the process of mountain building or orogenesis.  An orogeny is a period of time where mountain building occurs.
Ossicles small bones, especially one of the three bones of the middle ear.
"Out of Africa" hypothesis the hypothesis that modern humans originated in Africa (as did all other hominins), but then migrated into Asia and Europe.
Oxygen isotope records oxygen has two isotopes, oxygen-16 and oxygen-18. These exist in different proportions in the atmosphere, with O16 the most common. However, the proportions change with time and can give an indication of past climates. Tiny bubbles of gas trapped in Arctic and Antarctic ice cores can be analysed for their proportions of the two oxygen isotopes.
Paleomagnetism As magnetic particles are accumulated in sediments or incorporated into cooling magma (solidifying into rock), they align up on the Earth's magnetic field.  If that field reverses (something it has done many times through the Earth's history), the alignment will reflect the reversal.  Only rocks/sediments where the alignment is fixed can be assessed for their magnetic direction = palaeo (ancient) magnetism and these become a permanent record of past magnetic direction changes.
Pangaea (Greek for "all lands"): the supercontinent consisting of the present continents, first postulated by Alfred Wegener.
A peneplain is a surface of erosion.  They are often extensive and extend over many square km.
Pentadactyl having five digits on the hand or foot.
Perissodactyla non-ruminant ungulates with an uneven number of functional toes on each foot e.g. horses; tapirs; rhinoceros; extinct forms.
Pharyngeal having to do with to the region of the vertebrate gut between the mouth and the oesophagus, an area called the pharynx. In mammals this is the area that includes the throat and the back of the nose. In fish and non-vertebrate chordates the pharynx is more extensive, and is perforated by the pharyngeal (gill) slits.
Philopatric literally "home-loving"; here used for animals that return to the place where they were born to reproduce.
Photosynthesis the process in green plants, algae, cyanobacteria, and some other bacterial groups, by which carbohydrates are synthesised from carbon dioxide and water using light as an energy source. Most forms of photosynthesis release oxygen as a by-product. (Purple sulphur bacteria use CO2 and hydrogen sulphide, and do not produce oxygen.)
Phyla plural of phylum. A phylum is the taxonomic category immediately below Kingdom. Many texts use "phylum" only for the animal kingdom, with "division" the equivalent taxon in plants.
Phylogenetic to do with the evolutionary history of living things (see phylogenetic analyses).
Phylogeneticanalyses the analysis of evolutionary patterns and relationships, using the system of cladistics and information from a range of sources including comparative anatomy and embryology, molecular biology, palaeontology, and immunological techniques. The phylogenetic trees produced by these analyses are capable of rigorous testing.
Placental used to describe mammals in which the developing embryo is nourished via a placenta (distinguishing them from marsupials and monotremes).
Placoderms members of a group of extinct fish of the Silurian and Devonian periods, characterised by bony plates of armour covering the head and flanks, hinged jaws, and paired fins.
Plate boundaries the boundaries between the Earth's crustal plates. There are three types: boundaries of divergence or spreading plates; boundaries of convergence or collision of plates; and boundaries of plates that slide past each other i.e., transform boundaries.
Plesiosaurs large extinct marine reptiles, long-necked and short-bodied and with paddle-like limbs, that were common in the seas off Europe and North America during the Mesozoic Era.
Poikilohydric describes plants which cannot keep their water content constant e.g. mosses. Such plants dry out when their environment becomes dry, and remain dormant until wetted.
Polygynous a mating pattern in which a male mates with more than one female in a single breeding season e.g. birds of paradise, red deer.
Polyphyletic a term describing a group of taxa (e.g. species, families) which are placed in the same taxonomic group but do not all have the same common ancestor e.g. the taxon consisting of the algae is polyphyletic.
Postcranial skeleton the skeleton, excluding the cranium.
Pre-adapted where an organism has a set of features that it evolved in one ecological niche but which are beneficial to it if its environment changes. Such features are also described as exaptations. The lungs and limbs of lobe-finned fish are an example of exaptations, as they gave these animals an advantage in moving into a terrestrial environment.
Primate a mammal of the order Primata, which includes the anthropoids and prosimians, characterised by hands and feet with prehensile digits, a shortened snout, and a large brain.
Primordial having existed from the beginning; in an earliest or original stage or state; "aboriginal forests"; "primal eras before the appearance of life on earth"; "the forest primeval"; "primordial matter"; "primordial forms of life".
Prognathous the jaws protrude in front of the cranium i.e. the animal has a muzzle.
Prokaryotic prokaryotic cells do not have a distinct nucleus and have no membrane-bound organelles. Bacteria and cyanobacteria are examples of prokaryotes.
Prosimians animals belonging to the Prosimii, a suborder of primates that includes the lemurs, lorises, and tarsiers. x
Proton a stable, positively charged subatomic particle in the baryon family having a mass 1,836 times that of the electron.
Protozoans members of a large group of single-celled, usually microscopic, eukaryotic organisms, such as amoebas, ciliates, flagellates, and sporozoans.
Pterosaur an extinct flying reptile of the order Pterosauria from the Jurassic and Cretaceous periods e.g. pterodactyls. Pterosaurs had wings consisting of a flap of skin supported by the very long fourth finger on each forelimb.
Quadrate bone a bone between the base of the lower jaw and the skull in fish, amphibians, reptiles and birds. In reptiles and birds the quadrate articulates the lower jaw with the skull. In mammals it is represented by the "anvil" (incus), one of the ossicles in the middle ear.
 Xxx an animal that walks on all four feet.
Radioactivity spontaneous emission of radiation, either directly from unstable atomic nuclei or as a consequence of a nuclear reaction.
A group of single-celled animals (protozoa, or protocsista) which make a shell from silica.  This group is exclusively marine and have been around since the Cambrian.  There are many modern species.
Radium a rare, brilliant white, luminescent, highly radioactive metallic element found in very small amounts in uranium ores. Its most common isotope, radium 226, has a half-life of 1,622 years. Radium is used in cancer radiotherapy, as a neutron source for some research purposes, and as a constituent of luminescent paints.
Ratite birds an ancient group of birds characterised by having a breastbone (sternum) with no projecting keel. They also share a particular arrangement of the bones of their palate. The group comprises the ostrich, emu, rheas, cassowary, and kiwis, and the extinct moas and elephant birds.
Ray-finned fish whose fins are supported by a large number of thin, flexible rays of bone. Most familiar fish are ray-finned e.g. carp, trout, tuna.
Reptile a cold-blooded, usually egg-laying vertebrate of the class Reptilia e.g. snakes, lizards, crocodiles, and turtles. Reptiles have dry, scaly skin and breathe air. .
Respiration the process or processes that cells use to generate energy (usually as ATP) from the oxidation of foodstuffs. May be aerobic (using oxygen) or anaerobic (in the absence of oxygen).
Rhizoid slender rootlike filament by which mosses, liverworts, and fern gametophytes (- this is a new term - look up the definition in the glossary) attach to the substrate and absorb water and minerals.
Ribosomes tiny round structures composed of RNA and protein that are found in the cytoplasm of living cells. Ribosomes are the sites of protein synthesis.
RNA RiboNucleic Acid: a single-chain nucleotide polymer (c.f. the double helix of DNA), where the nucleotides are adenine, cytosine, guanine and uracil. It is found in all cells as transfer RNA (tRNA), messenger RNA (mRNA), and ribosomal RNA (rRNA) and is an essential part of the cell's protein synthesis mechanism.
Robust describes hominids with a relatively heavily-built skeleton and a skull with very prominent ridges and crests e.g. Australopithecus robustus, A. aethiopicus
Sagittal crests bony crests running lengthwise down the mid-line of the skull.
Sandstone a cemented or otherwise compacted detrital sediment composed predominantly of sand-sized (2 to 0.063 mm) grains.
Sea-floor spreading
This occurs at the edge of two tectonic plates where molten rock (magma) accumulates.  Magma is more bouyant than the surrounding cold (unmolten) rock so it rises toward the plate edges or margins in some areas, e.g., ocean ridges.  As the plates move apart, more magma accumulates and the plate gradually gets bigger.
This the process which describes the accumulation of sediments.  This usually occurs in water (marine or fresh), but also as the result of wind and ice action.
Seed fern (pteridosperm): an extinct Carboniferous gymnosperm that had fernlike fronds and bore microsporangia and seeds.
Seed plants any plant that produces seeds.
Sexually dimorphic describes the situation where the male and female of a species differ in size, shape, colour or morphology. Mallard ducks and red deer are strongly sexually dimorphic.
Shale a laminated sedimentary rock in which the constituent particles are predominantly of silt and clay sizes. Some shales have a high organic content and are termed 'oil shales'.
Slope deposits
Those sediments which accumulate on the continental slope.  These are usually fine-grained muds and sands. The continental slope is that part of the continental margin that is between the continental shelf and the continental rise or oceanic trench, and which has a relatively steep slope, of 3-6.
Solar system the region within which the Sun, and all the planets and other bodies that travel around it, move.
Solnhofen Limestone famous for their fossils. Although relatively rare, fossils from the Solnhofen Limestone may show exquisite detail, and often include fragile or soft-bodied organisms that usually leave no fossils at all, or only fragmentary ones. Archaeopteryx is perhaps the best known of the Solnhofen fossils.
Somatic relating to the cells of the body; any cell of an organism other than the gametes.
Speciation the evolution of new species. May be through cladogenesis, where one parent species splits into two new ones, or anagenesis, where one species gradually changes into another.
Species the fundamental category of taxonomic classification, ranking below a genus or subgenus and consisting of related organisms capable of interbreeding.
Sporangia structures that produce spores. These structures may be microsporangia, producing very small spores, or megasporangia, which produce larger spores.
Stapes ("stirrup", columella): the innermost of the three small bones of the mammalian middle ear.
Strata This is the plural of stratum, which means beds. As sediments and other geological materials accumulate, they form layers which are referred to as beds or strata. The study of multiple strata is called stratigraphy.
Stratigraphy the science of rock strata. It is concerned not only with the original succession and age relations of rock strata but also with their form, distribution, lithologic composition, fossil content, geophysical and geochemical properties. That is, stratigraphy deals with all characters and attributes of rocks as strata, and their interpretation in terms of environment or mode of origin, and geologic history. All classes of rocks, consolidated or unconsolidated, fall within the general scope of stratigraphy. Some non-stratiform rock bodies are considered because of their association with or close relation to rock strata.
Stromatolites laminated mounds generated by cyanobacteria living in warm, shallow, carbonate-rich marine environments. These structures accumulate as the result of the cyanobacteria trapping fine-grained sediment and cementing it. They represent some of the earliest fossils.
This process occurs when one crustal plate is forced (or sinks) below another.  An example of this occurs along the eastern margin of the North Island, New Zealand.  Subduction zones are often recognisable by the accompanying ocean trench.
Sympatric refers to populations of closely related species that occupy the same or overlapping geographic areas without interbreeding.
Synapsida extinct reptiles that lived from the Permian to Jurassic, and are considered ancestral to mammals. Synapsids are distinguished from other reptilian taxa by the presence of a single pair of openings (apses) in the temporal region of the skull.
Taxa plural of taxon.
Taxon a taxonomic category or group, such as a phylum, order, family, genus, or species.
Tethys elongated east-west seaway that separated Eurasia from Gondwana, except for a western junction from the early Palaeozoic to late Cretaceous.
Tetrapods the "four-footed" vertebrates (amphibians, reptiles, birds, mammals). All have a pair of forelimbs and a pair of hind limbs.
Theory a theory is a coherent explanation for a large number of facts and observations about the natural world.
A theory is:
  • Internally consistent & compatible with the evidence
  • Firmly grounded in & based upon evidence
  • Tested against a wide range of phenomena
  • Demonstrably effective in problem-solving
e.g. theory of gravity, theory of general & universal relativity, theory of evolution.
Tibia the "shin" bone: one of the two bones of the lower leg. The other lower leg bone is the fibula.
Trace fossils or ichnofossils, are fossilised traces left by the activity of extinct animals, e.g. footprints or burrows.
Transcurrent fault or strike slip fault, in which the net slip is practically in the direction of the fault strike, i.e. in dextral movements, points across the fault line move to the right.
Transform fault a fault formed as a result of compression with the relative movement dominantly horizontal, entire blocks of crust on either side of a fault move in opposing directions, e.g. Alpine fault in the South Island of New Zealand.
Transitional fossil one of a sequence of fossils, either numerous individual fossils that show a change between one species, or fossils from similar genera or families, linking an older group to a very different younger group.
Trilobites class of arthropods with an endoskeleton made up of three major parts (cephalon, thorax and pygidium), and divided longitudinally into a central axis and two pleural regions at the sides.
Tuatara a member of one of two nocturnal reptile species (Sphenodon punctatus or S. guntheri) that are found only on some of New Zealand's offshore islands. Tuatara are the only extant members of the Rhynchocephalia, an order that flourished during the Mesozoic Era. Some classifications now place the spenodonts with the lizards in the order Squamata, rather than in their own order Rynchocephalia.
Tuff a rock composed of compacted volcanic ash varying in size from fine sand to coarse gravel.
Understorey the layer (zone) of vegetation that grows below the canopy and above the forest floor.
Unisexual refers to those flowering plants that have separate male and female flowers. These flowers may be on the same (monoecious) or separate (dioecious) plants.
Uranium a heavy silvery-white metallic element, radioactive and toxic, and easily oxidised. U238 is the most abundant of its 14 known isotopes. The element occurs in several minerals, including uraninite and carnotite, from which it is extracted and processed for use in research, nuclear fuels, and nuclear weapons.
Vascular here used to describe plants that possess a system of xylem and phloem for transporting water and photosynthetic products, respectively, throughout the plant.
Vertebrates a subphylum of the phylum Chordata. Vertebrates have all chordate features at some time in their lives. They also have marked development of the brain, which is enclosed in a skull; a skeleton of cartilage or bone; a spinal column that partially or completely replaces the notochord; and a closed, relatively high-pressure cardiovascular system.
Vessels here used to describe one of the types of xylem tubules (the other is the tracheids) that conduct water in plants. Vessel elements are relatively short, wide cells arranged end-to-end, with the walls at the end of each cell effectively missing. Only flowering plants have vessels, while tracheids are found in all vascular plants.
Vestigial organs these are structures, often rudimentary, which have no apparent or predictable function e.g. the human tailbone, or coccyx; the pelvic and thigh bones of whales. They are often homologous to organs that are fully functional in other species. Sometimes vestigial organs can be detected in the embryo but are lost in later development e.g. the pharyngeal slits of vertebrate embryos.
Vicariance the separation or division of a group of organisms by a geographic barrier, such as a mountain or a body of water, resulting in differentiation of the original group into new varieties or species.
Volatile a volatile substance; a substance that changes readily from solid or liquid to a vapour.
Weta a wingless insect related to crickets and grasshoppers, which evolved about the same time as dinosaurs and has clung on in New Zealand. It occupies the ecological niche that rats and mice inhabit elsewhere.
Zircon A brown to colourless mineral, ZrSiO4, occurring in tetragonal crystals. It consists of silica and zirconia. A red variety, used as a gem, is called hyacinth. Colourless, pale-yellow or smoky-brown varieties from Ceylon are called jargon.

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