Paleontology : Glossary

Acanthodians A primitive group of Silurian to Permian jawed bony fishes, bearing bony spines in front of all but their caudal fins. (USGS Paleontology glossary)

Age of Mammals term found in popular books on evolutionary systematics for the Cenozoic era, beginning with the Paleocene Epoch when following the K-T (end Cretaceous) mass extinction, mammals underwent a huge evolutionary radiation and thus replaced reptiles as the dominant life on Earth. Paleontologist Björn Kurtén wrote a popular intelligent layperson book with the same title. The Age of Mammals is also the name of a mural by Rudolph Zallinger for the Yale Peabody Museum (link), which follows his earlier and better known The Age of Reptiles. The Age of Mammals has in turn been replaced by the Anthropocene or Age of Man, (Holocene) when humans dominate every conceivable environment and most other life forms (apart from weedy species) are suffering a mass extinction (Yes I know humans are also mammals, so technically speaking this is still the age of mammals, but I tend to think of age of mammals as a period of flourishing biodiversity). (MAK)

Age of Reptiles term found in popular books on evolutionary systematics for the Permian through to Cretaceous periods (but obviously originating with Victorian discoveries of "antediluvian monsters"), when reptiles (first mammal-like reptiles, then archosaurs and marine reptiles) were the dominant life on Earth. Paleontologist Edwin Colbert wrote a popular intelligent layperson book with the same title. The Age of Reptiles was followed by the Age of Mammals.

Age of Reptiles mural by Rudolph Zallinger

The Age of Reptiles is also the title of a 110-foot (30 meter) mural painted by Rudolph Zallinger depicting the time from the Devonian to the Cretaceous and featuring dinosaurs and other prehistoric animals (His The Age of Mammals mural is similar and covers the Cenozoic). The fresco sits in the Yale Peabody Museum in New Haven, Connecticut, and was completed in 1947 after three years of work. The Age of Reptiles was at one time the largest painting in the world, and depicts a span of nearly 350 million years in Earth's history. Painted in the Renaissance fresco secco technique, The Age of Reptiles was an important cultural influence during the 1950s-60s, images of which are often found in earlier books on paleontology, and was also the model for dinosaur toys. Despite its somewhat outdated view of dinosaurs (presenting them as slow, sluggish creatures), The Age of Reptiles is still notable for its historical and artistic merit and as the largest natural history painting in the world. It has been an inspiration to many visitors including both Robert Bakker and Peter Dodson, who credit it with influencing them to become paleontologists. Dodson was nearly moved to tears upon first seeing it as a college senior.

Agnatha name given to what was previously considered a class of jawless fish, including both Paleozoic ostracoderms and extant lampreys and hagfish. With the cladistic revolution, the term has been replaced by more phylogenetically accurate terms such as "basal vertebrate" (MAK)

Ammonite A coiled, chambered fossil shell of a cephalopod mollusc of the extinct subclass Ammonoidea. Traditionally divided into three types, according to suture: goniatites (Devonian to Permian) have simple lobes, ceratites (Triassic) have a saw-toothed pattern, and ammonites proper (Jurassic and Cretaceous) are the most complex, have fractal sutures with rounded lobes and saddles. Ammonoids appear in the Devonian and become very important as fossils from the Carboniferous through to the Cretaceous. There abundance, wide distribution, and short stratigraphic range make them excellent index fossils. (USGS Paleontology glossary)

Aperture A relatively large opening on the last-formed chamber of a foraminiferal shell; the mouth of a mollusc shell. (USGS Paleontology glossary, MAK)

Belemnite a Mesozoic to early Tertiary cephalopod mollusc with an internal cone-, bullet-, or cigar-shaped shell. In life a squid-like animal, along with their cousins the ammonites they were important members of the Mesozoic marine ecosystem.

Bivalve names any a mollusc that is a member of Class Bivalvia, a clade characterised by having two shells hinged together, as the oyster, clam, scallop, or mussel. The term is sometimes also used to refer to any animal with two halves to its shell such as an ostracod or brachiopod. Here Bivalve is used to refer specifically to the molluscan class. In contrast to brachiopods, the plane of symmetry is primitively between the valves (the two shells), although many types, for example oysters, developed different sized valves. The second largest class of mollusc, after gastropods. Common as fossils, especially during the Mesozoic and Cenozoic, and these animals remain an important element in marine ecologies, especially in the littoral region. (MAK)

Brachiopod meaning "arm foot", names any member of a major phylum of marine organisms with bivalved shell, in contrast to molluscan bivalves the plane of symmetry is through the mid-line of the shell, not between the valves. Filter feeding by means of a specialised organ called a lophophore. Abundant during the Paleozoic (most especially from the Ordovician to the Devonian), where, along with corals, they make up the majority of invertebrate fossils. Less common in the Mesozoic, and even less frequent in the Cenozoic. Cambrian-Recent. (MAK)

Bryozoa meaning "moss animal", is a phylum of exclusively aquatic and mostly marine colonial organisms. At one time thought to be related to brachiopods because of the common possession of a lophophore, this is now considered the result of convergence. Ordovician-Recent. (MAK)

Burgess Shale Konservat-Lagerstätten from the Middle Cambrian of British Columbia, preserves carbonised films which give a unique preservation of soft-bodied organisms and soft parts of hard-shelled organisms, provides an important window on the Cambrian explosion. The inspiration for Stephen Jay Gould's book Wonderful Life.

Calcareous Of, containing, or like calcite (calcium carbonate). (USGS Paleontology glossary)

Calcareous nanofossils Fossil remains of calcareous nanoplankton. Calcareous Nanoplankton are protists that normally produce coccoliths during some phase in their life cycle. (USGS Paleontology glossary)

Calcite A common rock-forming mineral: CaCO₃. Calcite can be white, colorless, or pale shades of gray, yellow, and blue. It readily effervesces (bubbles) in hydrochloric acid and is the principal component of limestone. (USGS Paleontology glossary)

Cambrian The earliest period of the Paleozoic era, spanning the time between 544 and 505 million years ago. Its name derives from Cambria, the Roman name for Wales, where rocks of this age were first studied. (USGS Paleontology glossary) Major diversification of life in the Cambrian Explosion. Numerous fossils; most modern animal phyla appear. First chordates appear, along with a number of extinct, problematic phyla. Reef-building Archaeocyatha abundant; then vanish. Trilobites, priapulid worms, sponges, inarticulate brachiopods, and many other animals numerous. Anomalocarids are giant predators, while many Ediacaran fauna die out. Prokaryotes, protists (e.g., forams), fungi and algae continue to present day. Gondwana emerges. Petermann Orogeny on the Australian Continent tapers off (550–535 Ma). Ross Orogeny in Antarctica. Adelaide Geosyncline (Delamerian Orogeny), majority of orogenic activity from 514–500 Ma. Lachlan Orogeny on Australian Continent, c. 540–440 Ma. Atmospheric CO2 content roughly 20–35 times present-day (Holocene) levels (6000 ppmv compared to today's 385 ppmv). (Wikipedia)

Carboniferous A period of time in the Paleozoic era that includes the Mississippian and Pennsylvanian subperiods and extended from 360 to 286 million years ago. The later Carboniferous was the time of great Coal Swamps. (USGS Paleontology glossary)

Cartilaginous fishes Class Chondrichthyes; fish having a skeleton composed mostly of cartilage, as sharks and rays. Cartilage is gristle or a firm, elastic, flexible type of connective tissue. (USGS Paleontology glossary)

Cenozoic ("new animal life") the current of the three Phanerozoic eras in the geological timescale. It began 65.5 million years ago. The era when the modern continents formed, mammals and birds filled the ecological niches vacated by dinosaurs, and modern taxa of plants and invertebrates evolved. The later part of the Cenozoic was marked by a pronounced cooling, culminating in the Pleistocene ice age. Includes two periods, the Tertiary and Quaternary, and seven epochs, the Paleocene, Eocene, Oligocene, Miocene, Pliocene, Pleistocene, and Holocene.

Chalk soft, earthy, fine-grained white to greyish limestone of marine origin. It is composed almost entirely of by shallow-water accumulations of coccoliths and other microscopic organisms and forms in a sea predominantly free from terrestrial sediment. (from Glossary - Bristol University)

Chelicerate "claw horn bearing". Subphylum Chelicerata , Morphologically distinct arthropod clade characterized by have chelicera (a pair of pre-oral appendages), including arachnids (spiders, mites, etc), horseshoe crabs, scorpions and eurypterids ("sea scorpions"). Cambrian to recent. (University of Arizona Geosciences 308 Paleontology glossary)

Chronospecies One or more species which continually changes from an ancestral form along an evolutionary scale. This sequence of alterations eventually produces a population which is physically, morphologically, and/or genetically distinct from the original ancestors. Throughout this change, there is only one species in the lineage at any point in time, as opposed to cases where divergent evolution produces contemporary species with a common ancestor. Relies on an extensive fossil record, since morphological changes accumulate over time and two very different organisms could be connected by a series of intermediaries. The related term paleospecies indicates an extinct species only identified with fossil material. To avoid unnecessary multiplication of terminology (and paleontology-neontological distinctions) these terms are here synonymised. For example, changes in the Permian lepospondyl amphibian Diplocaulus over time may imply a chronospecies (= paleospecies). (MAK, Wikipedia)

Cnidaria meaning "nettle bearing", is a phylum of solitary or colonial, sessile or free-living, predatory organisms with specialized stinging cells called nematocytes (or cnidoblasts), and frequently having distinctive morphologies for asexual and sexual reproduction. Cnidarians include jellyfish, corals, hydrozoans and others. In older books the name Coelenterate is used instead. (University of Arizona Geosciences 308 Paleontology glossary)

Coal swamp name given to the vast equatorial tropical forests and swamplands of the late Carboniferous, from which most modern black coal comes from (brown coal in contrast is Tertiary in age). Despite the name, coal swamps did not themselves contain any coal. (MAK) Page with links to dioramas

Coccoliths Microscopic structures of varying shape and size that are made of calcite, are secreted by calcareous nanoplankton, and are found in marine deposits from the Triassic period to the Recent. Coccoliths range in size from one to thirty-five micrometers in size. (USGS Paleontology glossary), found only in warm, low-latitude waters and hence useful for understanding ancient climates. (Glossary - Bristol University)

Coral Class Anthozoa, sessile Cnidaria, solitary or colonial polyp-like animals, may be soft-bodied (sea anemone) or secret a stony skeleton (this is the familiar coral). Often reef-building organisms. Include the Paleozoic Rugose and Tabulate corals, both common or very common as fossils in rocks of Ordovician to Permian age, and the Mesozoic to Recent scleractinian corals.

Cretaceous The final period of the Mesozoic era, spanning the time between 145 and 65 million years ago. The name is derived from the Latin word for chalk ("creta") and was first applied to extensive deposits of this age that form white cliffs along the English Channel between Great Britain and France. (USGS Paleontology glossary) Flowering plants proliferate, along with new types of insects. More modern teleost fish begin to appear. Ammonites, belemnites, rudist bivalves, echinoids and sponges all common. Many new types of dinosaurs (e.g. tyrannosaurs, titanosaurs, duck bills, and horned dinosaurs) evolve on land, as do Eusuchia (modern crocodilians); and mosasaurs and modern sharks appear in the sea. Primitive birds gradually replace pterosaurs. Monotremes, marsupials and placental mammals appear. Break up of Gondwana. Beginning of Laramide and Sevier Orogenies of the Rocky Mountains. Atmospheric CO2 close to present-day levels. (Wikipedia)

Crinoid sea lily, (Subphylum Crinozoa, Class Crinoidea) a type stalked and filter-feeding echinoderm that was very common during the Paleozoic, especially the early Carboniferous, and continues to flourish today, mostly in deep sea environments.

Crustacean Subphylum Crustacea. Large group of mostly marine arthropods (although there are also some freshwater types and even a few terrestrial ones). Include shrimps, lobsters, crabs, barnacles, krill, ostracods, and terrestrial slaters and pillbugs. Morphologically distinct from other arthropods (hence given their own subphylum), but according to molecular phylogeny closely related to insects. Cambrian to recent.

Cyanobacteria common name "blue-green algae", a type of photosynthetic Eubacteria, one of the most primitive forms of life on Earth. Form stromatolites, and the "scum" on rocks and in showers. Archean to recent.

Cynodont mostly Triassic mammal-like reptiles, from which true mammals evolved. (MAK)

Devonian A period of the Paleozoic era, spanning the time between 410 and 360 million years ago. It is named after Devonshire, England, where rocks of this age were first studied. (USGS Paleontology glossary) First clubmosses, horsetails and ferns appear, as do the first seed-bearing plants (progymnosperms), first trees (the progymnosperm Archaeopteris), and first (wingless) insects. Strophomenid and atrypid brachiopod, rugose and tabulate corals, and crinoids are all abundant in the oceans. Goniatite ammonoids are plentiful, while squid-like coleoids arise. Trilobites and armoured agnaths decline, while jawed fishes (placoderms, lobe-finned and ray-finned fish, and early sharks) rule the seas. First amphibians still aquatic. "Old Red Continent" of Euramerica. Beginning of Acadian Orogeny for Anti-Atlas Mountains of North Africa, and Appalachian Mountains of North America, also the Antler, Variscan, and Tuhua Orogeny in New Zealand. (Wikipedia)

Dinocyst A resting stage or reproductive stage in the life cycle of a dinoflagellate. (USGS Paleontology glossary)

Dinoflagellate Small organisms with both plant-like and animal-like characteristics, in earlier taxonomies usually classified as algae (plants). They take their name from their twirling motion and their whip-like flagella. (USGS Paleontology glossary); found as fossil from the mid Triassic to the present. Modern dinoflagellates are often responsible for the phosphorescence of the sea and toxic red tide. Fossil dinoflagellates are used to date and correlate rocks from the Triassic to the Quaternary. (Amateur Geologist Glossary)

Echinoderm meaning "spiny skinned", names any member of Phylum Echinodermata; a large group of primarily pentamerally radially symmetrical exclusively marine metazoans with internal calcite skeletons and hydrostatic vascular system. Includes crinoids (sea lilies), echinoids (sea urchins, sand dollars, sea biscuits), holothurians (sea cucumbers), asteroids (starfish), ophiuroids (brittle star), and many exclusively Paleozoic groups such as blastoids, edrioasteroids, carpoids, and others. (University of Arizona Geosciences 308 Paleontology glossary)

Echinoid Subphylum Echinozoa, Class Echinoidea. Sea urchins and their relatives. Echinoderms with spherical or flattened bodies, often protected by long spines, like starfish they move about on tube feet. Very common as fossils, especially in the Cretaceous and Tertiary. Ordovician - Recent (rare prior to the Jurassic). (MAK)

Ediacaran most recent period of the Proterozoic era, characterised by the appearance of both enigmatic Vendobionta and trace fossils that seem to pertain to more conventional organisms. The term Ediacaran was replaced for a while by Vendian, but now it seems that Ediacaran is back in fashion. (MAK)

Ediacaran biota enigmatic life forms from the Ediacaran period; the first large to appear. Their affinities remain highly controversial; they have been interpreted as the first representatives of current animal phyla (Cnidaria, Annelida, Arthropoda, etc), as sister group to all metazoa more derived than sponges, as a totally distinct kingdom (Vendobionta, Vendozoa), and even as marine fungi and giant Rhizarian protists. Each hypothesis has advantages and disadvantages going for it. (MAK)

Eocene An epoch of the early Tertiary period, spanning the time between 55.5 and 33.7 million years ago. Its name is from the Greek words ἠώς (eos, dawn) and καινός (kainos, new)). It was a period of global greenhouse climate and lush forests, in which small to large archaic mammals, large reptiles, and giant flightless birds all flourished. (USGS Paleontology glossary, MAK, Perseus Digital Library) Moderate, cooling climate. Archaic mammals (e.g. Creodonts, Condylarths, Uintatheres, etc) flourish and continue to develop during the epoch. Appearance of several "modern" mammal families. Primitive whales diversify. First grasses. Reglaciation of Antarctica and formation of its ice cap; Azolla event triggers ice age, and the Icehouse Earth climate that would follow it to this day, from the settlement and decay of seafloor algae drawing in massive amounts of atmospheric carbon dioxide, lowering it from 3800 ppmv down to 650 ppmv. End of Laramide and Sevier Orogenies of the Rocky Mountains in North America. Orogeny of the Alps in Europe begins. Hellenic Orogeny begins in Greece and Aegean Sea. (Wikipedia)

Eurypterid colloquially known as "sea scorpions", these were medium-sized to gigantic, marine to freshwater to amphibious Paleozoic chelicerates, include the largest arthropods ever to live (up to 2.5 meters long). Ordovician to Permian, most common during the late Silurian and early Devonian, although also flourished in Carboniferous swamps. (MAK)

Foraminifer Amoeboid protozoans traditionally included under the subclass Sarcodina, order Foraminifera, but more recently reclassified as Rhizaria. They have a test (shell) of one to many chambers composed of secreted calcite or agglutinated particles. They have a comprehensive fossil record, and are very important in stratigraphy. (USGS Paleontology glossary)

Form taxon binomial name given to a fossilized plant organ when it is found in isolation, i.e. when the taxonomic affinities of the organ are not known with certainty; for example spore and pollen taxa have their own binomial names, since it is rarely known which fossil genus may have produced them. (UCMP)

Fossil mineralized or otherwise preserved remains or traces (such as footprints) or impressions of animals, plants, and other organisms. (from Wikipedia glossary); Evidence of past life on earth. Can include the preserved hard and soft parts of plants and animals, tracks and burrows, whole organisms preserved intact in amber or tar, and fossilized dung. Any evidence of life constitutes a fossil. (GeoMan)

Fossil record the history of life on Earth through geological time, as preserved through fossil remains in sedimentary rock (sometimes referred to poetically in older books as the record of the rocks). Also the fossil history of any particular group.

Fossilization All the processes that involve the burial of a plant or animal in sediment and the eventual preservation of all, part, or a trace of it. (USGS Paleontology glossary)

Gondwana The southern land mass derived from the supercontinent of Pangea, which continued until its break-up during the Cretaceous and early Tertiary. It comprised of Antarctica, Africa, South America, Australia and India. The term is also used to describe these same continents when connected as a supercontinent in the Paleozoic, prior to Pangea. Gondwana means "Land of the Gonds" (a tribe from the Indian subcontinent). Note, the popular term Gondwanaland is therefore redundant.

Graptolite "painted stone", mostly planktonic, Paleozoic, colonial hemichordates with a chitinous skeleton (periderm), commonly preserved as carbon films in black shales, common during the Ordovician, Silurian, and early Devonian, important as index fossils 240 genera are known. (MAK, University of Arizona Geosciences 308 Paleontology glossary)

Gymnosperm "naked seeds", after the unenclosed condition of their seeds (called ovules in their unfertilized state). Their naked condition stands in contrast to the seeds or ovules of flowering plants (angiosperms) which are enclosed during pollination. Includes conifers, cycads, Ginkgo, Gnetales, and extinct groups such as "seed ferns". (Wikipedia)

Hadean First of the four eons of the geological timescale, the earliest subdivision of the Precambrian, spanning the time between the formation of the Earth, about 4.5 billion years ago, and the start of the Archean era, 3.8 billion years ago. This interval predates the period of true geologic time since no rocks of this age are known on Earth, with the exception of a few meteorites. Except possibly for the very end of the Hadean, conditions were too harsh to support life (hence the name, after the underworld of Greek mythology). (USGS Paleontology glossary, MAK)

Holocene An epoch of the Quaternary period, spanning the time from the end of the Pleistocene (10,000 years ago) to the present. The most recent period of geologic history, which extends from 10,000 years ago to the present. It is named after the Greek words ὅλος (holos, entire) and καινός (kainos, new). See also Anthropocene. (MAK, USGS Paleontology glossary, Perseus Digital Library) The last glacial period ends; rise of human civilization. Quaternary Ice Age recedes, and the current interglacial begins. Younger Dryas cold spell occurs, Sahara forms from savannah, and agriculture begins, allowing humans to build cities. Paleolithic/Neolithic (Stone Age) cultures begin around 10000 BC, giving way to Copper Age (3500 BC) and Bronze Age (2500 BC). Cultures continue to grow in complexity and technical advancement through the Iron Age (1200 BC), giving rise to many pre-historic cultures throughout the world, eventually leading into Classical Antiquity, such as the Roman Empire and even to the Middle Ages and present day. Little Ice Age (stadial) causes brief cooling in Northern Hemisphere from 1400 to 1850. Also refer to the List of archaeological periods for clarification on early cultures and ages. Mount Tambora erupts in 1815, causing the Year Without a Summer (1816) in Europe and North America from a volcanic winter. Following the Industrial Revolution, Atmospheric CO2 levels rise from around 280 parts per million volume (ppmv) to the current level of 390 ppmv, due to anthropogenic emissions, very likely causing global warming and climate change. (Wikipedia)

Ichnology branch of paleontology that deals with traces of organismal behavior, such as burrows and footprints. Thus, burrows, trackways, trails and borings are all examples of biogenic structures, but not casts or molds of dead shells or other bodily remains. To keep body and trace fossils nomenclatorially separate, ichnospecies are erected for trace fossils. Ichnotaxa are classified somewhat differently in zoological nomenclature than taxa based on body fossils. Examples include:

• Late Cambrian trace fossils from intertidal settings include Protichnites and Climactichnites, amongst others
• Mesozoic dinosaur footprints including ichnogenera such as Grallator, Atreipus and Anomoepus
• Triassic to Recent termite mounds, which can encompass several square kilometers of sediment

(from Wikipedia)

Ichnotaxon defined by the International Code of Zoological Nomenclature as "a taxon based on the fossilized work of an organism". Ichnotaxa are names used to identify and distinguish morphologically distinctive ichnofossils, more commonly known as trace fossils. They are assigned genus and species ranks by ichnologists, much like organisms in Linnaean taxonomy. These are known as ichnogenera and ichnospecies, respectively. Ichnotaxa include trace fossils such as burrows, borings and etchings, tracks and trackways, coprolites, gastroliths, regurgitaliths, nests, leaf mines, bite and gnaw structures, secretions modified by organismal activity, such as cocoons, pupal cases, spider webs, embedment structures and plant galls. (from Wikipedia)

Index fossil A fossil that identifies and dates the strata in which it is typically found. To be most useful, an index fossil must have broad, even worldwide distribution and must be restricted to a narrow stratigraphic range. (S.M. Richardson)

Jurassic The middle period of the Mesozoic era, spanning the time between 213 and 145 million years ago. It is named after the Jura Mountains between France and Switzerland, where rocks of this age were first studied. (USGS Paleontology glossary). Gymnosperms (especially conifers, Bennettitales and cycads) and ferns common. Many types of dinosaurs, such as sauropods, carnosaurs, and stegosaurs. Mammals common but small. First birds (Archaeopteryx) and lizards. Ichthyosaurs and plesiosaurs diverse. Bivalves, ammonites and belemnites abundant. Sea urchins very common, along with crinoids, starfish, sponges, and terebratulid and rhynchonellid brachiopod. Breakup of Pangaea into Gondwana and Laurasia. Nevadan orogeny in North America. Rantigata and Cimmerian Orogenies taper off. Atmospheric CO2 levels 4–5 times the present day levels (1200–1500 ppmv, compared to today's 385 ppmv). (Wikipedia)

Konservat-Lagerstätten see Lagerstätten.

Lagerstätten (more correctly called Konservat-Lagerstätten): a term coined by German paleontologists for exceptionally preserved fossil assemblages. Most contain direct evidence of soft part morphology. Examples include Mazon Creek (concretions, Carboniferous, Illinois), Solnhofen Limestone (extremely fine grained (lithographic) limestone, Jurassic, Germany), La Brea (tar pits, Pleistocene, California), Burgess Shale (carbonization, Cambrian, Canada). (University of Arizona Geosciences 308 Paleontology glossary)

Limestone the most abundant of the non-clastic sedimentary rocks that is produced from the mineral calcite (calcium carbonate) and sediment. The main source of limestone is the limy ooze formed in the ocean. The calcium carbonate can be precipitated from ocean water or it can be formed from sea creatures that secrete lime such as algae and coral. (Fossil Mall)

Living fossil informal term for any living species (or genus or clade) of organism which appears to be the same as a species otherwise only known from fossils and which has no close living relatives. These species have all survived major extinction events, and generally retain low taxonomic diversities. For example, the inarticulate brachiopod Lingula has not noticeably changed since the Ordovician period. One famous example is the coelacanth, which was thought to have become extinct with the dinosaurs at the end of the late Cretaceous, until a live specimen was caught in 1938 (Jewett1998). A species which successfully radiates (forming many new species after a possible genetic bottleneck) has become too successful to be considered a "living fossil". Lazarus taxon would seem to be a more or less synonymous term. (MAK, Wikipedia)

Macrofossil A fossil that is large enough to be studied without a microscope. (USGS Paleontology glossary)

Mesozoic the second of the three Phanerozoic eras of the geological timescale, between the Paleozoic and the Cenozoic, and lasting from 251 to 65.5 million ago. More or less equivalent (especially in the popular imagination) to the "age of reptiles". Dinosaurs, pterosaurs, marine reptiles, ammonites, gymnosperms, and primitive mammals and birds all flourished. The word Mesozoic is from Greek and means "middle life." Includes three periods: the Triassic, Jurassic, and Cretaceous. (MAK, USGS Paleontology glossary)

Microfossil A fossil so small that it must be studied with a microscope. (USGS Paleontology glossary)

Micron Micrometer, a unit of measure, used for example when describing protists and microfossils. There are one million micrometers in one meter. (MAK, USGS Paleontology glossary)

Miocene A epoch of the late Tertiary period, spanning the time between 23.8 and 5.3 million years ago. It is named after the Greek words μείων (meion, less) and καινός (kainos, new). (USGS Paleontology glossary, Perseus Digital Library) Moderate Icehouse climate, punctuated by ice ages; Orogeny in northern hemisphere. Modern mammal and bird families become recognizable. Horses and mastodons diverse. Grasses become ubiquitous. First apes appear (for reference see the article: "Sahelanthropus tchadensis"). Kaikoura Orogeny forms Southern Alps in New Zealand, continues today. Orogeny of the Alps in Europe slows, but continues to this day. Carpathian orogeny forms Carpathian Mountains in Central and Eastern Europe. Hellenic orogeny in Greece and Aegean Sea slows, but continues to this day. Middle Miocene Disruption occurs. Widespread forests slowly draw in massive amounts of CO2, gradually lowering the level of atmospheric CO2 from 650 ppmv down to around 100 ppmv. (Wikipedia)

Mississippian A subperiod of the Paleozoic era, spanning the time between 360 and 325 million years ago. It is named after the Mississippi River valley, which contains good exposures of rocks of this age. The term is used by American geologists as a period ranking of geological time, but not European ones, who refer instead to the "Lower Carboniferous". The Mississippian has since been standardised as subperiod of the Carboniferous (MAK, USGS Paleontology glossary) Large primitive trees, first land vertebrates, and amphibious sea-scorpions live amid coal-forming coastal swamps. Lobe-finned rhizodonts are dominant big fresh-water predators. In the oceans, early sharks are common and quite diverse; echinoderms (especially crinoids and blastoids) abundant. Corals, bryozoa, goniatites and brachiopod (Productida, Spiriferida, etc.) very common, but trilobites and nautiloids decline. Glaciation in East Gondwana. Tuhua Orogeny in New Zealand tapers off. Variscan orogeny occurs towards middle and late Mississippian Periods. (Wikipedia)

Mold fossilised impression of organism preserved in rock. External molds are impressions of the outside of a structure, while internal molds (also known as steinkerns) are impressions of the inside of structure. Composite molds are formed when the original material dissolves, and the external and internal mold are pressed together. Both external and internal features are preserved on a composite mold. (University of Arizona Geosciences 308 Paleontology glossary)

Mollusca also mollusk (American spelling) major phylum of invertebrate animals distinguished by a shell-secreting mantle and radula teeth. Includes chitons, bivalves, gastropods, cephalopods, and various minor groups. An important component in marine ecosystems, also many freshwater and terrestrial forms. Cambrian to recent.

Morphological species concept, population-based concept, defines a species by its body shape, size, and other structural features. Unlike the Biological Species Concept in that it can be applied to the systematic study of fossil organisms, and hence adopted by paleontologists. Compare with Paleontological species concept.

Mosasaur giant marine reptiles, probably related to the ancestors of snakes. They dominated the seas during the late Cretaceous. (MAK)

Nautiloid the pearly nautilus and its ancestors. Include a large assemblage of mostly Paleozoic cephalopods with straight, curved, loosely or tightly coiled shells and simple sutures. Common and most diverse from the Ordovician to the Devonian, after which time they were increasingly supplanted by ammonoids. Nevertheless, nautiloids much like the modern Nautilus continued virtually unscathed even when the various groups (goniatites, ceratites, ammonites) of their advanced ammonoid cousins died out, perhaps because they inhabited deeper water and were not so dependent on the plankton-based food chain. The largest Paleozoic nautiloids had straight shells several meters or more in length, but most species were of more modest proportions. MAK

Neogene A subperiod of the Tertiary period of the Cenozoic era, Includes the Miocene and Pliocene epochs. A move to have the Paleogene and Neogene replace the Tertiary was not successful, and they now seem to have become subperiods. (MAK)

Neontology An infrequently used word, and used only then by paleontologists to refer to those aspects of biology that, in contrast to paleontology, deal with now living or extant organisms. From neos = new, ontos = being, logos = study of). In another sense, more or less equivalent to biology. Neontologists have access to data that is difficult or impossible for paleontologists to access for extinct species, such as anatomy and soft-part morphology, physiology, molecular sequences, embryology, histology, and more, and therefore make essential contributions to systematic paleontology and phylogeny. In general, and understandably because of the far greater amount and diversity of data that neontology provides, cladistics tends to be more orientated to neontology (hence taxonomy orientated to crown clades) and evolutionary systematics to paleontology. However the tendency in the total evidence and supermatrix approach now is to integrate and consider both paleontological and neontological data. (MAK)

Oligocene An epoch of the early Tertiary period, spanning the time between 33.7 and 23.8 million years ago. It is named after the Greek words ὀλίγος (oligos, little, few) and καινός (kainos, new). (USGS Paleontology glossary, Perseus Digital Library) Warm but cooling climate, moving towards Icehouse; Rapid evolution and diversification of fauna, especially mammals. Major evolution and dispersal of modern types of flowering plants. (Wikipedia)

Ordovician The second earliest period of the Paleozoic era, spanning the time between 505 and 440 million years ago. It is named after a Celtic tribe called the Ordovices. (USGS Paleontology glossary) Invertebrates diversify into many new types (e.g., long straight-shelled cephalopods). Early corals, articulate brachiopod (Orthida, Strophomenida, etc.), bivalves, nautiloids, trilobites, ostracods, bryozoa, many types of echinoderms (crinoids, cystoids, starfish, etc.), branched graptolites, and other taxa all common. Conodonts (early planktonic vertebrates) appear. First green plants and fungi on land. Ice age at end of period. (Wikipedia)

Osteology literally, the "science of bones"; the study of the various parts of the vertebrate skull and skeleton. Regardless of how much neontology and soft-part morphology, paleobiological reconstruction (especially popularised by the dinosaur renaissance of Ostrom, Bakker, and Paul), developmental biology, and molecular phylogeny increase in importance in studying the evolution of vertebrates, along with trace fossils and footprints, the study of the most durable and commonly preserved parts of the organism, the teeth (in small delicate animals such as Mesozoic mammals) and bones will always remain an essential element in any analysis of vertebrate phylogeny and paleontology. Classic vertebrate paleontology textbooks and papers such as the works of Zittel, Romer and Carroll are full of dense descriptions on the skeletal and cranial minutiae of various extant and extinct taxa, and even more so this is the case with technical journals. Thus material, essential for listing traits for cladistic analysis, makes up a large part of the "Vertebrates" section of Palaeos.com (originally, "Vertebrate Notes"). (MAK)

Ostracod Class Ostracoda - small crustaceans with dorsally located bivalved carapace which is commonly heavily calcified, common as microfossils and very useful for biostratigraphy. (University of Arizona Geosciences 308 Paleontology glossary, MAK)

Ostracoderm name given to a diverse assemblage of highly distinctive armoured jawless fish from the Ordovician, Silurian and Devonian periods. The term is now rarely used in scientific literature, as they are now known to consist of a number of different lineages, and are a paraphyletic or even a polyphyletic grouping. Nevertheless it is a useful label for referring to these bizarre creatures from the early days of vertebrate evolution. (MAK)

Paleoanthropology the study of fossil hominids, especially human ancestors.

Paleoart informal term first coined by Mark Hallett for art that depicts subjects related to paleontology. These may be representations of fossil remains or depictions of the living creatures and their ecosystems (Wikipedia). Paleoartists therefore are any of those wonderfully talented people who produce those beautiful reconstructions of prehistoric organisms that help to brighten up the web (and Palaeos too). (MAK)

Paleobiogeography The branch of paleontology that deals with the geographic distribution of plants and animals in past geologic time, especially with regard to ecology, climate, and evolution.

Paleobiology The study and understanding of fossil organisms from a biological perspective. Whereas paleontology looks at the fossil bone, shell, or leaf for its own sake, paleobiology seeks to understand the organism that produced those remains.

Paleoceanography The study of oceans in the geologic past, including its physical, chemical, biologic, and geologic aspects. (USGS Paleontology glossary)

Paleocene Earliest epoch of the Tertiary period, spanning the time between 65 and 55.5 million years ago. It is named after the Greek words παλαιός (palaios, old) and καινός (kainos, new). (USGS Paleontology glossary, Perseus Digital Library) Climate tropical. Modern plants appear; mammals diversify into a number of primitive lineages following the extinction of the dinosaurs. First large mammals (up to bear or small hippo size). Alpine orogeny in Europe and Asia begins. Indian Subcontinent collides with Asia 55 Ma, Himalayan Orogeny starts between 52 and 48 Ma. (Wikipedia)

Paleogene A subperiod of the Tertiary period of the Cenozoic era, Includes the Paleocene, Eocene, and Oligocene epochs. A move to have the Paleogene and Neogene replace the Tertiary was not successful, and they now seem to have become subperiods. (MAK)

Paleomagnetism Refers to the study of the magnetic properties of rocks and minerals. This demonstrates to us that both the strength and direction of Earths magnetic field is not constant. Each rock and mineral tells its own story at a particular moment in time. (A. Atwal, Wikiversity)

Paleoneurology branch of neurology concerned with the study of the evolution of the brain by using fossil evidence, such as brain endocasts of extinct vertebrates. This little known field has been pioneered by American biopsychologist Harry J. Jerison. more/link

Paleontological species concept Species concept which focuses on morphologically discrete species known only from the fossil record, the Morphological species concept would be similar or synonymous.

Paleontology. The scientific study of ancient life (palaeos = ancient, ontos = being, logos = speech, reason, hence study of), through examination of fossil remains and the fossil record. Includes subdivisions such as Vertebrate, Invertebrate, and Micro- paleontology. Contrast with neontology. Paleontologists have access to many extinct forms of life, including many transitional and ancestral forms, and information regarding their stratigraphic or temporal position in the geological timescale, paleobiology, paleoecology, paleoclimatology, etc extend this to environmental, geographic, and other areas to provide a comprehensive history of the Earth. Because of the fragmentary or partial nature of many fossils, reconstructing extinct life and extinct environments is often more like forensic science than biology or ecology. (MAK)

Paleosol A fossil soil or soil horizon. (MAK)

Paleozoic the first and longest of the three Phanerozoic eras of the geological timescale, , lasting from 542 to 251 million years ago. Characterised by the emergence and dominance of multicellular life in the Cambrian explosion, and the succession of invertebrates, fish, and early land plants, amphibians and reptiles. Includes six periods: the Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian. The word Paleozoic is from Greek and means "ancient animal life."

Palynology The study of pollen, living and fossil. (Amateur Geologist Glossary)

Pangea, Pangaea meaning "all the earth", is a supercontinent that existed during the Permian and Triassic, and included most of the Earth's continental crust. During this time, terrestrial faunas were often quite uniform, as there were few geographic barriers, although there were distinct vegetation zones (biomes). Beginning in the Jurassic, Pangea divided into Laurasia in the north and Gondwana in the south.

Pennsylvanian A subperiod of the Carboniferous period of the Paleozoic era, spanning the time between 325 and 286 million years ago. It is named after the state of Pennsylvania where rocks of this age are widespread. (USGS Paleontology glossary) Winged insects radiate suddenly; some (esp. Protodonata and Palaeodictyoptera) are quite large. Amphibians common and diverse. First reptiles and coal forests (scale trees, ferns, club trees, giant horsetails, Cordaites, etc.). Highest-ever atmospheric oxygen levels. Goniatites, brachiopod, bryozoa, bivalves, and corals plentiful in the seas and oceans. Testate forams proliferate. Uralian orogeny in Europe and Asia. (Wikipedia)

Period a unit or division of geological time, usually lasting several tens of millions of years, and hence intermediate in duration between era and epoch. By convention, each period is divided into two or more epochs. In terms of geological strata, rather than time, the word "system" is traditionally used, although this now seems to be falling out of favour, and only found in older books. (MAK)

Permian The final period of the Paleozoic era, spanning the time between 286 and 248 million years ago. It is named after the province of Perm, Russia, where rocks of this age were first studied. (USGS Paleontology glossary) Landmasses unite into supercontinent Pangaea, creating the Appalachians. End of Permo-Carboniferous glaciation. Synapsid reptiles (pelycosaurs and therapsids) become plentiful, while parareptiles and temnospondyl amphibians remain common. In the mid-Permian, coal-age flora are replaced by cone-bearing gymnosperms (the first true seed plants) and by the first true mosses. Beetles and flies evolve. Marine life flourishes in warm shallow reefs; productid and spiriferid brachiopod, bivalves, forams, and ammonoids all abundant. Permian-Triassic extinction event occurs 251 Ma: 95% of life on Earth becomes extinct, including all trilobites, graptoloids, and blastoids. Ouachita and Innuitian orogenies in North America. Uralian orogeny in Europe/Asia tapers off. Altaid orogeny in Asia. Hunter-Bowen Orogeny on Australian Continent begins (c. 260–225 Ma), forming the MacDonnell Ranges. (Wikipedia)

Permo-Carboniferous informal period of time encompassing the Carboniferous and Permian periods, or alternatively the latter parts of the Carboniferous and early part of the Permian period. Important in considering late Paleozoic geology, global climate change (glaciation), and plant, invertebrate, and tetrapod ecology and evolution. (MAK)

Phanerozoic the most recent, and current, of the four eons of the geological timescale, the time of diverse and complex life, complex ecosystems, and an oxygen-rich atmosphere. Divided into Paleozoic, Mesozoic, and Cenozoic. The Phanerozoic begins with the start of the Cambrian period, and continues to today.

Placoderms A peculiar group of primitive armored jawed fish, superficially similar to Ostracoderms, and found almost exclusively in rocks from the Devonian Period. (USGS Paleontology glossary, MAK)

Pleistocene An epoch of the Quaternary period, spanning the time between 1.8 million years ago and the beginning of the Holocene at 8,000 years ago. It is named after the Greek words "pleistos" (most) and "ceno" (new). The period of the last ice age, characterised by many large mammals, as well as modern plants and invertebrates. Modern humans evolved during this time. (USGS Paleontology glossary, MAK) Flourishing and then extinction of many large mammals (Pleistocene megafauna). Evolution of anatomically modern humans. Quaternary Ice Age continues with glaciations and interstadials (and the accompanying fluctuations from 100 to 300 ppmv in atmospheric CO2 levels[20]), further intensification of Icehouse Earth conditions, roughly 1.6 Ma. Last glacial maximum (30000 years ago), last glacial period (18000–15000 years ago). Dawn of human stone-age cultures, with increasing technical complexity relative to previous ice age cultures, such as engravings and clay statues (e.g. Venus of Lespugue), particularly in the Mediterranean and Europe. Lake Toba supervolcano erupts 75000 years before present, causing a volcanic winter that pushes humanity to the brink of extinction. Pleistocene ends with Oldest Dryas, Older Dryas/Allerød and Younger Dryas climate events, with Younger Dryas forming the boundary with the Holocene. (Wikipedia)

Pliocene Final epoch of the Tertiary period, spanning the time between 5.3 and 1.8 million years ago. It is named after the Greek words πλεῖον (pleion, more) and καινός (kainos, new). The Miocene and Pliocene represented the time of greatest abundance and diversity of the mammals. Characterised by a cooling climate and ice sheets in Antarctica. (USGS Paleontology glossary, MAK, Perseus Digital Library) Intensification of present Icehouse conditions, present (Quaternary) ice age begins roughly 2.58 Ma; cool and dry climate. Australopithecines, many of the existing genera of mammals, and recent mollusks appear. Homo habilis appears. (Wikipedia)

Precambrian older term, now rarely used, to refer to the expanse of geological time prior to the Cambrian period. Because the Cambrian was when animal fossils first appear, it, and the following periods to the present, were called the Phanerozoic, and was contrasted with earlier ages and their corresponding rock strata, often highly metamorphosed, and devoid of fossils (or characterised only by stromatolites). The Precambrian was also known as the Cryptozoic (hidden life), and originally referred to as "Primary" strata. Current understanding and research has revealed the Precambrian to be a time of diverse geological, climatological, and microbiological activity and evolution. Current usage replaces "Precambrian eon" with three distinct eons, Hadean, Archean, and Proterozoic, with complex life forms only appearing at the end of the latter, during the Ediacaran period. (MAK)

Proterozoic the most recent, and current, of the four eons of the geological timescale, during which occurred the oxygen crisis, snowball earth, the rise of Eukarya, and the origin of multicellular life. It followed the Archean, and lasted from around 2.5 to half a billion years.

Pterosaur "winged lizard" or "winged finger" (pterodactyl); Order of Mesozoic flying archosaurian reptiles characterised by a greatly elongated fourth digit that supported a membranous wing (in contrast to bats in which all five digits are elongated; artwork and movies that give pterosaurs bat-like wings are inaccurate). They include the largest animals ever to fly, although others were of more modest proportions. Pterosaurs were not dinosaurs, but were closely related, both are included under the clade Ornithodira. (MAK, Fossil Mall glossary)

Quaternary The second period of the Cenozoic era (following the Tertiary), spanning the time between 1.8 million years ago and the present (in terms of duration, this is the shortest period, equivalent to a standard age). It contains two epochs: the Pleistocene and the Holocene. It is named after the Latin word "quatern" (four at a time), and refers to the earliest (19th century) stratigraphic systems (Primary, Secondary, Tertiary, and Quaternary). Although there was a movement to scrap both Tertiary and Quaternary in favour of more modern terms such as Paleogene and Neogene, this was not successful, and in current geological timescales the Quaternary has been restored or retained. The Quaternary includes both the Ice Age with its distinctive megafauna, and the modern, human-dominated period of Earth history. (USGS Paleontology glossary, MAK)

Rudist A type of extinct bivalve mollusk from the Jurassic and especially the Cretaceous that had two different sized and shaped shells; they usually were attached to the substrate and were either solitary or in reeflike masses. (USGS Paleontology glossary)

Rugose "wrinkled". Order Rugosa: Paleozoic group of mostly solitary, but some colonial, stony corals; 800 genera known. Common as fossils. (adapted from University of Arizona Geosciences 308 Paleontology glossary)

Reworked a fossil that was eroded out of its original strata and then redeposited in more recent strata, giving the impression that the organism lived at a later date than it did. e.g. some isolated dinosaur fossils have been found in Paleocene strata, leading some to argue that they survived the end Cretaceous extinction. (MAK)

Sauropod, sauropodomorph "lizard footed", a misleading name for these giant creatures with their chubby elephant-like feet. One of the three main clades of dinosaurs, the other two being theropods and Ornithischia. Early sauropodomorphs, called prosauropods, were small to medium sized animals, but they quickly grew to become sauropods proper, the largest animals to walk the Earth. Sauropods are characterised by very small heads (relative to the overall body), long to very long necks and tails, solid pillar-like legs, and massive dorsal vertebrae. At one time they were believed to be sluggish semi-aquatic wallowers in swamps, unable to walk on land. It is now known that they were active and fully terrestrial animals, much like elephants. Adults were so large they were immune to predation even from the biggest theropods. (MAK)

Scanning Electron Microscope (SEM) A microscope in which a finely focused beam of electrons is scanned across a specimen, and the electron intensity variations are used to construct an image of the specimen. This type of microscope is ideal for magnifications from 200 to 35,000. (USGS Paleontology glossary)

Signor-Lipps effect Principle that states that, since the fossil record of organisms is never complete, neither the first nor the last organism in a given taxon will be recorded as a fossil. (Signor&Lipps82). The Signor-Lipps effect can reduce the apparent severity of a catastrophic extinction by making it appear to be extended in time. It is named after its authors, Philip W. Signor and Jere H. Lipps . (Wikipedia)

Silurian A period of the Paleozoic, spanning the time between 440 and 410 million years ago. It is named after a Celtic tribe called the Silures. (USGS Paleontology glossary) First Vascular plants (the rhyniophytes and their relatives), first millipedes and arthropleurids on land. First jawed fishes, as well as many armoured jawless fish, populate the seas. Sea-scorpions reach large size. Tabulate and rugose corals, brachiopod (Pentamerida, Rhynchonellida, etc.), and crinoids all abundant. Trilobites and mollusks diverse; graptolites not as varied. Beginning of Caledonian Orogeny for hills in England, Ireland, Wales, Scotland, and the Scandinavian Mountains. Also continued into Devonian period as the Acadian Orogeny, above. Taconic Orogeny tapers off. Lachlan Orogeny on Australian Continent tapers off. (Wikipedia)

Suture the line of partition between gas-filled chambers in shelled cephalopods. Sutures can only be seen when the outside of the shell has been removed, and suture pattern is used to characterize many ammonoid groups. Nautiloids have simple sutures, ammonites more complex ones. (MAK, University of Arizona Geosciences 308 Paleontology glossary)

Stratigraphy Branch of geology concerned with the formation, composition, ordering in time, and arrangement in space of sedimentary rocks. (USGS Paleontology glossary)

Stromatolite algae mats, formed in shallow water by microorganisms, especially cyanobacteria accreting grains in layers. Rare now, but common during the Proterozoic. The oldest stromatolites are known from the Archean, they are among the oldest records of life on Earth. Image (right) Wikipedia; (MAK)

Subperiod optional unit of geological time intermediate between period and epoch. (MAK)

Tabulate Order Tabulata. Paleozoic group of exclusively colonial organisms traditionally classified as stony corals, although other interpretations have been suggested (e.g. sponges). Common as fossils, 280 genera known. (adapted from University of Arizona Geosciences 308 Paleontology glossary)

Tethys during the time of Pangea (Permian and Triassic) this was the sea that separated the northern half (Laurasia) of the supercontinent from the southern (Gondwana). If Pangea can be imagined in the shape of a giant "pac-man", then the Tethys is the "mouth". During the Triassic especially, the borders of the Tethys were populated by unique animals, such as the walrus and turtle like placodonts. (MAK)

Tertiary The first period of the Cenozoic era (after the Mesozoic era and before the Quaternary period), spanning the time between 65 and 1.8 million years ago. This was the Age of Mammals proper, before the rise of man. It is divided into two subperiods, Paleogene and Neogene, and five epochs, Paleocene, Eocene, Oligocene, Miocene, and Pliocene. (USGS Paleontology glossary)

Trace fossil fossil not of an organism itself (e.g. shell, bone, mold, carbonised impression) but of the traces and impressions it left behind while alive (footprints, burrows, resting traces, etc. The study of trace fossils is called Ichnology. (MAK)

Treatise on Invertebrate Paleontology massive multi-authored multi-authored work-in-progress (beginning 1953 and still ongoing), with contributions by more than 300 paleontologists, and covering every phylum, class, order, family, and genus of fossil and extant invertebrates. Published by the Geological Society of America and the University of Kansas Press. Raymond C. Moore, the project's founder and first editor, originally envisioned this Treatise in invertebrate paleontology as comprising just three large volumes, and totaling only three thousand pages. It has already run to some 50 volumes and tens of thousands of pages; some groups have not yet been covered, while others are being revised. The work is so large and on-going that it spans paradigms; the first volumes followed the standard evolutionary taxonomy of the day, more recent revisions, for example brachiopods, involve phylogenetic systematics. The Russian (at the time Soviet) equivalent, Osnovy paleontoligii (Fundamentals of paleontology) (editor in chief Yuri Orlov) was a less ambitious but still huge 15 volume work that was began in 1962. (MAK, Wikipedia)

Triassic The earliest period of the Mesozoic era, spanning the time between 248 and 213 million years ago. The name Triassic refers to the threefold division of rocks of this age in Germany. (USGS Paleontology glossary) Archosaurs dominant on land as dinosaurs, in the oceans as Ichthyosaurs and nothosaurs, and in the air as pterosaurs. Cynodonts become smaller and more mammal-like, while first mammals and crocodilians appear. dicta flora common on land. Many large aquatic temnospondyl amphibians. Ceratitic ammonoids extremely common. Modern corals and teleost fish appear, as do many modern insect clades. Andean Orogeny in South America. Cimmerian Orogeny in Asia. Rangitata Orogeny begins in New Zealand. Hunter-Bowen Orogeny in Northern Australia, Queensland and New South Wales ends, (c. 260–225 Ma). (Wikipedia)

Trilobite important class of Paleozoic marine arthropods, distinguished by a three-fold division of the exoskeleton. Most were small (a few centimeters) although a few giants reached half a meter or so. Abundant during the Cambrian, where they make up the majority of invertebrate fossils. Also very common during the Ordovician to the Devonian, but declined thereafter. Their exquisite forms and great variety of species make them a favourite of most fossil collectors. Morphologically distinct; relationships with other arthropods unclear, hence included in a distinct subphylum, the Trilobitomorpha. Cambrian-Permian. (MAK)

Victorian age in Britain and the British colonies, the period of Queen Victoria's reign (from 1837 to 1901). A long and prosperous period, and also a time of great scientific, technological, and social advancement. Evolutionary thinking and the science of paleontology are among the developments that stem from this period (and also from equivalent contemporary developments in France, Germany, and the United States).

Vertebrates animals with backbones. Because bones easily fossilise, the vertebrate fossil record is excellent in comparison to that of other more delicate organisms, e.g. insects, or soft-bodied invertebrates.