Terms & Definitions

Ammonites

An extinct cephalpod with a coiled shell, complex immovable joints, and a tube-like structure located along the outer margin.

Arthropod

Invertebrate animals that are characterized by an exoskeleton and a segmented body to which jointed appendages are arranged in pairs.

Belemnite

An extinct squid-like cephalopod with a solid, bullet-shaped internal shell.

Brachiopods

Lamp shells, possess two dissimilar valves that are bilaterally symmetrical.

Bryozoans

Any of various small aquatic animals that form moss-like or branching colonies that permanently attach to stones or seaweed.

Cambrian

A period 540 to 505 million years ago. The sea levels rose, the atmospheric levels of oxygen rose, no evidence of life being on land, but there were primitive algae, seaweeds, jellyfish, and sponges in the water.

Cambrian Explosion

A great multiplication of life forms seen in the paleontological record dating from about 600 million years ago.

Carboniferous

A period 360 to 286 million years ago. The warm climate cooled to an ice age in the southern hemisphere. This was the age of amphibians. The first reptiles appeared, snails, centipedes and millipedes, cockroaches, and giant dragonflies we also present. The sea life consisted mainly of ammonoids, brachiopods, corals, and some mollusks.

Carnivore

A flesh-eating animal.

Cephalopods

Advanced invertebrate animals with a head bearing prominent eyes and a mouth surrounded by tentacles.

Ceratites

An ammonoid found in mid-Triassic rocks of Europe. Its shell is characterized by coarse radiating ridges.

Cetaceans

Any of various aquatic, chiefly marine mammals, including the whales, dolphins, and porpoises, characterized by a nearly hairless body, front limbs modified into broad flippers, under-developed rear limbs, and a flat, notched tail.

Conifers

Any of various mostly needle-leaved or scale-leaved, chiefly evergreen, cone-bearing gymnospermous trees or shrubs such as pines, spruces, and firs.

Coprolites

Fossilized excrement.

Cretaceous

A period 144 to 66 million years ago. The seas flooded half of the land, and the land masses began to move towards where they are today. There were advanced dinosaurs such as duck-bills, gulls, and wading birds. Plankton, coral reefs, and rudists were extinct by the end of the period.

Crinoids

Any of various echinoderms, including the sea lilies and feather stars, that are characterized by a cup-shaped body, feathery radiating arms, and either a stalk or clawlike structure with which they are able to attach to a surface.

Devonian

A period 407 to 360 million years ago. Eurasia and North America were situated in the tropics. The first amphibians, horsetails and clubmosses appeared. This was known as the Age of Fishes. Some specimens were jawed and jawless bony fish, armoured fish, lobe-fin fish, and cartilaginous fish.

Diatom

Microscopic unicellular marine or freshwater colonial algae having cell walls impregnated with silica.

Diatryma

An extinct Eocene bird from New Mexico, larger than the ostrich.

Dinornis

A genus of extinct, ostrich-like birds of gigantic size, which formerly inhabited New Zealand.

Echinoderms

Any of numerous symmetrical marine invertebrates, which includes starfishes, sea urchins, and sea cucumbers, having an internal skeleton and often covered with spines.

Eocene Epoch

Lasting from 57 to 36 million years ago; presence of modern mammals.

Fetus

An unborn or unhatched vertebrate in the later stages of development showing the main recognizable features of the mature animal.

Gastrolith

A small stone found in the stomach of some reptiles, fish, and birds that aids in digestion by helping grind ingested food material.

Genus

A group of related species.

Herbivore

An animal that feeds chiefly on grass and other plants.

Holocene Epoch

Approximately the last 10,000 years, includes the growth of human civilization and the rise of technology.

Ichthyosaurs

Any of various extinct fishlike marine reptiles of the order Ichthyosauria of the Triassic Period to the Cretaceous Period, having a porpoise-like head and an elongated, toothed snout.

Jurassic

A period 210 to 144 million years ago. Seas flooded much of the land, and on the continents mountains continued to form. Reptiles were dominant with crocodiles, turtles, lizards, and dinosaurs. Mammals began to diversify, and more advanced insects such as flies were present.

Lithification

The process by which an unconsolidated deposit of sediments is converted into solid rock. Compaction, cementation, and recrystallization are involved.

Mammoth

An extinct, hairy, maned elephant of enormous size, remains of which are found in the northern parts of both continents. The last of the race, in Europe, were coeval with prehistoric man.

Marsupial

Any of various nonplacental mammals of the order Marsupialia, including kangaroos, opossums, bandicoots, and wombats, found principally in Australia and the Americas.

Mass Extinction

Large-scale wiping out of groups of animals.

Mastodon

Extinct elephant-like mammal that flourished worldwide from Miocene through Pleistocene times; differ from mammoths in the form of the molar teeth.

Meteorites

A stony or metallic mass of matter that has fallen to the earth's surface from outer space.

Ordovician

A period 505 to 440 million years ago. All the land masses moved south, floods subsided, but returned and covered more land than at any other time. Primitive algae and seaweed plants existed, and sea life such as corals, bryozoans, brachiopods, and jawless armoured fishes.

Paleobotany

The branch of paleontology that deals with plant fossils and ancient vegetation.

Paleocene

From 58 million to 63 million years ago; appearance of birds and earliest mammals.

Permian

A period 286 to 245 million years ago. Pangaea headed towards the north, and the climates were generally cooler. Reptiles began to take over the amphibians, and giant clubmosses, seeds, ferns, horsetails, pines, and firs appear for the first time.

pH

Literally meaning potential of hydrogen; a measure of the acidity or alkalinity of a solution. The pH scale ranges from 0 to 14, where 7 is neutral. As the number increases from 7, the alkalinity increases, while as the number decreases from 7, the acidity increases.

Plate Tectonics

A theory of global dynamics having to do with the movement of a small number of semi-rigid sections of the earth's crust, with seismic activity and volcanism occurring primarily at the margins of these sections. This movement has resulted in continental drift and changes in the shape and size of ocean basins and continents.

Pleistocene

An Epoch from 2 million to 10,000 years ago; extensive glaciation of Northern hemisphere; time of human evolution

Plesiosaurs

A large extinct marine reptile having paddle-like limbs that was common in Europe and North America during the Mesozoic Era.

Pliocene

An Epoch from 5 million to 2 million years ago; growth of mountains; cooling of climate; more and larger mammals.

Pollinate

Fertilize by transferring pollen.

Proto

First in time; earliest. First formed, primitive, original.

Quaternary

A period from 1.8 million years ago to present. Ice covered the northern lands, and the sea levels fell. There were wooly mammoths, rhinos, saber-toothed cats, giant marsupials in Australia, and human hunting skills developed because mammals started to disappear.

Sedimentary Rocks

Rocks that are formed by sediments, worn away by wind, water, or from other rocks, and deposited in water where they have hardened to form a new layer or strata. Almost all fossils are found in sedimentary rocks.

Shale

A sedimentary rock formed by the deposition of successive layers of clay.

Silurian

A period 440 to 407 million years ago. North America and Eurasia joined, producing the Caledonian mountains, and the continents were flooded by shallow seas. Scorpians, millipedes, and possibly euryterids came out of the water during this period. There were marine invertebraes, crinoids, brachiopods, trilobites, nautiloids, and graptolites.

Strata or Stratum

A bed or layer of sedimentary rock having approximately the same composition throughout.

Teratornis

Literally meaning "monster bird", was an early condor-like bird. This giant, extinct predator had a wingspan of roughly 5-7.6 meters. Dates from the Pleistocene Epoch.

Tertiary

A period 66 to 1.6 million years ago. Characterized by the appearance and diversification of modern flora and of large mammals, including apes.

Tetrapods

A vertebrate animal with four feet, legs, or leglike appendages.

Theropod

Any of numerous carnivorous dinosaurs of the Triassic to Cretaceous with short forelimbs that walked or ran on strong hind legs.

Triassic

A period 245 to 210 million years ago. The sea levels were very low, and it was during this period that the Atlantic Ocean opened up. The reptiles were dominant, and gymnosperms such as ferns, cycads, gingkos, and conifers were present.

Trilobites

Any of numerous extinct marine arthropods of the Paleozoic Era, having a segmented body divided by grooves into three vertical lobes and found as fossils throughout the world.