98 ■ PALAEONTOLOGY/GENERAL
palaeontology (n) the study of the life of past geological times; the study of fossils (J.), palaeontological (adj).
paleontology (n) American spelling of palaeontology (|). paleontologic (adj).
biosphere (n) that part of the world in which living things are present: the surface of the land, the soil, the seas, and 1he air
organism (n) a living individual plant or animal.
fossil (n) the remains of an animal or plant preserved in a rock; a cast (j) or impression or a trace (|) of an animal or plant in a rock, fossil, fossilized (adj), e.g. a fossil fish, fossilized wood; fossilize (v).
fossiliferous (adj) containing fossils (f),
fossil record all the remains of past animal and plant life found in the rocks.
mould (n) the impression left in a rock by a fossil (or other object). A mould may be external (an impression made by the outside of the fossil) or internal (a cast ([) of the inside of a fossil).
cast (n) a copy of a fossil (or other object) formed by the filling in of a mould {]■), A cast may be internal or external, i.e. of the inside or of the outside of the fossil.
trace fossiI a sedimentary strudure (p.83) formed by an animal moving across or moving in the sediment when it was being deposited, e.g. tracks, footprints, and burrows (holes made by animals).
fauna (r>) the animals that live together in any one place or area at a particular time. A fossil fauna consists of all the animals thai are found as fossils in a particular stratigraphical unit (p.113)- a bed, for example-in a particular area, faunal (adj). See also flora (p.110)
trace fossil
PALAEONTOLOGY/TAXONOMY - 99
numbers of families of all groups during Phanerozolc time
microfossil (n) a very small fossil (f): one that can be seen only with a microscope. Some microfossils are important in stratigraphical palaeontology (p. 111), e.g. the Foraminifera (p.104).
micropalaeonotology (n) the study of microfossils (f). micropalaeontological (adj).
microfauna (n) a fauna (j) of microlossils (f). taphonomy (n) the study of the ways in which
fossils (f) are formed, taxonomy (n) the science of arranging animals
and plants, whether living or fossilized (t). in
groups or classes according to their structure.
taxonomic (adj). taxon (r?) (taxa) a taxonomic group or unit of
classification, e.g. a genus (I), a family (|).
taxonomic {adj). phylum (n) (phyla) one of the main divisions of
the animal or plant kingdom, e.g. Insects
(p.108). Mammalia (p.109), class (n) a division of a phylum (1) order (n) a division of a class (f). superfamily (n) a division of an order (t). Names
of superfamilies end in -oidea. family (n) a division of an order ( f ) Names of
animal families end in -idae. subfamily (n) a division of a family ( f ). Names of
animal subfamilies end in -inae. genus (n) (genera) a division of a family (f),
containing one or more species {I). The name
of a genus is a Latin word, written with a capital
letter, e.g. Ungula. species (n) a division of a genus (f). The
members of a species are all very much alike.
In living forms they interbreed among
themselves, i.e. they can become parents of
young, who can in turn also become parents
Pairs from different species cannot, on the other
hand, produce young. The name of a fossil
species is a Latin word, written with a small
letter, which comes alter the name of the genus,
e.g. Didymograptus murchisoni type (n) a fossil that represents the characters of
a species (|). a holotype; or a genus (f), a
genotype.
100 ■ PALAEONTOLOGY/PALAEOECOLOGY
PALAEONTOLOGY/PALAEOECOLOG Y • 101
palaeoecology (n) the study of fossil animals and plants in relation to the conditions under which they (ived-the environment (p.81). palaeobiogeography (n) the study of the way in which animals and plants were arranged in space on the surface of the Earth in the geological past, habitat (n) the environment (p.81) in which an
animal or plant lives or lived, assemblage (n) (1) all the fossils that are present in a particular bed or stratum (p.80); (2) the fossils of a species (p.99), or some other small group, from a particular horizon (p.112) or place; (3)agroupof fossils found by themselves that are thought to belong to one animal-fossil community a group of fossils found in the same place where they lived together.
a shell-bed community with lamellibranchs, ammonites, echinoids, etc.
plankton (n) all the organisms that float in the sea or in a lake and are carried about by the movement of (tie water; e.g. Foraminifera (p.104) and Radiolaria(p.104). planktonic {adj).
microplankton (r>) the smallest members of the plankton (f); those that cannot easily be seen with the unaided eye.
phytoplankton (n) all the plant forms that float in the sea or in lakes. See also plankton (f).
nekton (n) all the animals that swim in (he sea or in lakes.
benthos (n) all the animals and plants that live on the sea floor, benthonic {adj).
pelagic (adj) animals that live in the open sea but not on the sea floor are called pelagic. They include the nekton (|) and the plankton (f).
a sessile fossil; a cririDid
aerobic (adj) needing free oxygen in order to live
or be active. See also anaerobic (I). anaerobic {adj) not needing oxygen in order to
live or be active. See also aerobic (1). epifauna {n) a fauna (p.98) that in life is fixed to
another and larger organism (p.98), epizoon (n) an organism of an epifauna (1).
epizoan (adj)-sessile {adj) describes an organism (p.98) that
is closely attached to a surface, such as the sea
floor or another organism. Applied to benthos
(f), 'sessile' means attached to the sea floor.
See also sedentary (i). sedentary {adj) describes an organism (p,98)
that is attached, as, for example, an oyster.
See also sessile (f )• biocoenose (n) an assemblage (|) of organisms
(p.98) thai live together as one community (f). biolith (n) a deposit of organic (p. 17) material or
material formed by the activities of organisms,
bioherm (n) an organic deposit (p.80) built largely or entirely of the remains of fixed organisms (p.98); a fossil reef (p.38), A bioherm is usually shaped like a small hill. It is a special type of biolith (f).
biostrome (n) a mass of organic material in the form of a sheet or bed (p.80) built by sedentary organisms ( f , p,98) that have been preserved in pi ace. See ateo bioherm (f)
biogenic (adj) produced by organisms (p.98).
stromatolites (n) rounded sedimentary structures (p.83) formed by the plants called algae (p. 110), which live in water. The oldest stromatolites are of Pre-Cambnan age (p 114) and are among the oldest fossils known
102 ■ PALAEONTOLOGY/EVOLUTION
PALAEONTOLOGY/EVOLUTION ■ 103
evolution (n) the process by which new forms of living things can develop from earlier forms by passing on small changes from one generation to the next, evolutionary (adj), evolve (v).
adaptation (n) a character ot an organism (p.98) that fits it for a particular environment {p.81); (2) the process by which an organism (p.98) is changed to become more fit for its environment (p.81). adaptive (adj), adapt (v).
natural selection the process that according to Darwin's theory controls which members of a population of animals or plants will live to produce young and pass on their genes (p. 156) to the next generation.
adaptive radiation the development of new species (p.99) that takes place when the descendants of a taxon (p.99) evolve (f) by natural selection (f) in fitting themselves to various environments (p.81).
mutation (n) a discontinuous change in a gene (p. 156) or an organism (p.98) that can be inherited, i.e. passed on to its descendants, mutate (V)
ancestral {adj) referring to organisms (p.98) from which later organisms are descended.
ontogeny (n) the course followed by the life history of an individual animal or plant.
phylogeny (n) the course followed by the evolulion (t) of a species (p.99) or other taxonomic (p.99) group, phylogenetic (adj).
diversity (species) the range of variation that is shown by a species (p.99).
diversification (n) the process of becoming more diverse, lhat is, more different, diversify (v).
lineage (n) a line of descent from earlier members of the same or a similar group of animals or plants; a series of fossils that show a course of evolution (f).
divergence (n) the development of a new population of organisms from an earlier one-diverge (v). divergent (adj)
radiation (n) the evolutionary divergence (f) of a group of species, radiate (v), radiating (adj).
extinction (n) the dying out of a (whole) group of animals or plants, extinct (adj).
phylogenetic tree
extinctions and appearances o* new lorms during
divergence
convergence
X
parallel descent
\
homoeomorphy
evolutionary patterns
convergence (n) the development ot similar forms in different groups of plants or animals at different places or at different limes because of the effects produced by similar environments on their separate evolutions (f). convergent (adj).
polyphyletic (adj) a group of organisms (p 98) is polyphyletic if its members have evolved (|) from different series ol earlier forms by convergent evolution (f).
trend (n) the evolution (f) of a particular structural feature within a group of organisms (p 98),
transient (n) a stage in the phylogeny (f) of a species; a stage in any closely spaced evolutionary (|) series (p 159).
homoeomorphy (n) the occurrence of similar forms (shapes) in members of the same phylum (p.99).
explosive evolution a diversification (|) that for a time takes place much more rapidly than at other times; eg the very rapid evolution of the fishes in the late Silurian and early Devonian (P 114).
evolutionary burst = explosive evolution (f). quantum evolution the sudden appearance
within a short space of geological time of large
taxonomic (p.99) units, e.g. orders (p.99). See
also explosive evolution (|). speciation (n) the production of new species
(p.99) by the splitting or division of earlier
species in the course of evolution (f). bioseries (n) an evolutionary (f) series of fossils.
It may be a series (p. 159) of whole individuals
or a series of specimens that show trends in
particular features, cladogenesis (n) the development of species
(p.99) by division of the line of descent. See
diagram.
cladistics (n) a cladistic classification is one thai is based on the branching pattern (fhe cladogram) of the evolution of a group of animals. Groups that have separated from each other more recently are put closer together than those thai have separated at earlier limes. This type of classification is unlike those that have been used in the past.
112 STRATIGRAPHY/GENERAL
STRATIGRAPHY/TIME AND OTHER DIVISIONS -113
stratigraphy (n) the study of stratified rocks (p.80), their nature, their occurrence, their relationships to each other and their classification, stratigraphical, stratigraphic (USA) (adj).
historical geology the study of the history of the Earth. I! includes stratigraphy (j).
Uniformitarianism (n) the view that geological processes were of the same kind in the pas1 as they are today and produced similar results. See also Catastrophism (J,).
Catastrophism (r?) the view, no longer held in geology, that the history of the Earth has to be explained by a series of violent events or catastrophes. See also Uniformitarianism (f)
succession (n) the order in which rock-groups appear. When a succession is set out in the form of a table the beds (p. 80) are shown with the oldest at the bottom and the youngest at the top.
superposition (n) 1he order in which rocks are placed one above the other. The principle or law of superposition is that in a layered succession (\) of rocks the lower beds (p.80) will be the older and the upper beds will be the younger (unless the rocks have been turned upside down).
time plane a surface within a series of sedimentary rocks that marks a particular moment in geological time.
horizon (n) (1) a plane of stratification (p.80) that was once horizontal and continuous, (2) a time plane (f) within a sedimentary series (i)ora bed (p.80) (usually a thin bed) that contains characteristic fossils or has a characteristic lithology (p.85).
sequence (n) a succession (f) of bedded rocks, the stratigraphical (f) order in which beds appear.
cyclic sequence a sequence (f) of sediments (p.80) repeated in a particular order, eg. sandstone - shale - limestone. A cyclic sequence is commonly the result of marine transgression (p.119) and regression (p.119) cycfothem (n) a unit of a cyclic sequence(f) rhythmic sequence a cyclic sequence (f) on a small scale.
succession
bed A is Ihe oldest bed E Ihe youngest (if not inverted)
lime periods
aeon, eon (n) the largest division of geological
time. An aeon is made up of several eras ([). era (n) a division of geological time; made up of
several periods (J.) or sub-eras (i). sub-era (n) a division of an era (f). period (n) a large division of geological time; it
corresponds to a system (|). epoch (n) a division of geological time, part of a
period (|); it corresponds to a series (1). age (n) a division of geological time; part of an
epoch (t), it corresponds to a stage (I), chron (n) the smallest division of geological time,
part of an age. chronostratigraphical {adj) a chronostrati-
graphical unit is a division of the geological
column (1) that is based on geological time.
See also lithostratigraphical (I).
biostratigraphical (p.117). system (n) one of the major stratigraphical (j)
divisions of the geological column (f); it
corresponds to a geological period (f) series (rr) a stratigraphical division within a system
(f); it corresponds to an epoch(f) stage (n) a stratigraphical division within a series
(t); i( corresponds to an age (f). lithostratigraphical (adj) a lithostratigraphical
unit is one that is based on lithological (p.85)
characters rather than on geological time or
lossils. See also chronostratigraphical (f),
biostratigraphical (p. 117). rock-stratigraphical (adj) = lithostratigraphical
CD-group (n) a lithostratigraphical term (f) lor a rock unit consisting of two or more formations (I) that are next to each other in a succession (|} and are related to each other formation (n) a term for the basic lithostratigraphical (|) division, member (n) a lithostratigraphical (]) term for a
part of a format ion (f). bed (n) the smallest lithostratigraphical (t)
division. See also p.80. geological column a diagram that shows the divisions of geological lime and the succession (t) for a given area.
114 ■ STRATIGRAPHY/GEOLOGICAL SYSTEMS
STRATIGRAPHY/GEOLOGICAL SYSTEMS -115
Precambrian, Pre-Cambrian (n, adj) the period of time before the Cambrian { j ), i.e. from the formation of the Earth until about 570 million years ago: about 4000 million years. Proterozoic (n, adj) (1)one of two aeons (p.113) into which the Precambrian { f ) is divided, ranging from 2500 to 570 million years ago. (2) the whole of the Precambrian,
Archaean (n, adj) (1) the earlier of two aeons (p. 113) into which the Precambrian ( \ ) is divided, covering the period from the formation of the Earth until 2500 million years ago; (2) the whole of the Precambrian.
basement complex, basement a general term for igneous (p 62) or metamorphic (p. 90) rocks, usually Precambrian (f), which cover a wide area and on which rest unmetamorphosed (p.90) sediments of later age.
Phanerozoic (n. adj) the stratigraphical systems from the Cambrian (].) to the Recent {[).
Palaeozoic (r>, adj) the era of geological time that ranges from 570 to 230 million years ago. It is divided into the Lower Palaeozoic, consisting of the Cambrian (J), Ordovician (I), and Silurian (I) periods, and the Upper Palaeozoic, consisting of the Devonian (j), Carboniferous {!), and Permian (|) periods.
Cambrian (n, adj) the earliest period of the Palaeozoic era, dating from about 570 million years ago to 500 million years ago.
Ordovician (n, adj) a period of the Palaeozoic Era (t). dating from 500 to 435 million years ago.
Silurian (n, adj) a period of the Palaeozoic Era (j), dating from 435 to 400 million years ago.
Devonian (n, adj) a period ol the Palaeozoic Era (f), dating from 400 to 345 million years ago.
Carboniferous {n, adj) a period of the Palaeozoic Era (T), dating from 345 to280 million years ago. In the USA it is divided into the Mississippian (below) and 1he Pennsylvanian (above).
Mississippian (n, adj) see Carboniferous (f).
Pennsylvanian (n, adj) see Carboniferous (f)
Permian {n, adj) the latest period of the Palaeozoic Era (f), dating from 280 to 230 million years ago.
2SO
500
Ma 0 T
200.
Tertiary
Mesozoic (n, adj) the era between the Palaeozoic (\) and the Cainozoic (I), ranging from 230 to 65 million years ago. It is made up of the Triassic, Jurassic, and Cretaceous periods.
Trrassic (n, adj) the earliest period of the Mesozoic Era(f). ranging from 230 to 195 million years ago,
Trias = Triassic (|).
Jurassic (n, adj) one of the three periods of the Mesozoic Era (?), ranging from 195 to 140 million years ago
Cretaceous (n, adj) the youngest of the three periods of the Mesozoic Era {T), ranging from 140 to 65 million years ago
Cainozoic, Cenozoic (n, adj) the era of geological time that follows the Mesozoic (T), ranging from 65 million years ago to the present It is made up of the Tertiary and Quaternary sub-eras (i)
Tertiary (n, adj) the sub-era between the Cainozoic era (\) and the Quaternary sub-era (i), ranging from 65 million years ago to 2 million years ago. It is divided into two periods, the Palaeogene and the Neogene, and five epochs: the Palaeocene, Eocene, Oligocene, Miocene, Pliocene, Pleistocene, and Holocerte
Palaeocene (n, adj) see Tertiary (t).
Eocene [n, adj) see Tertiary {]).
Oligocene (n, adj) see Tertiary (j).
Miocene (n, adj) see Tertiary (j).
Pliocene (n, adj) see Tertiary (j).
Palaeogene (r>, adj) 1he earlier of the two periods of (he Tertiary sub-era (|). It consists of Ihe Palaeocene, Eocene, and Oligocene epochs (t).
Neogene (n, adj) the later ot the two periods ol the Tertiary sub-era (| )■ It consists ol the Miocene and Pliocene epochs (j).
Quaternary {n, adj) the period from 2 million years ago to the present, a subdivision (sub-era) of the Cainozoic Era (]). It is divided into two epochs, the Pleistocene (1) and Hotocene (i).
Pleistocene (n, adj) an epoch of the Quaternary sub-era (t), the time of the last ice age.
Holocene (n, adj) the latest epoch of the Quaternary sub-era (t); it includes the present time.
Recent = Holocene (f).
116 - STRATIGRAPHY/PERfODS OF MOUNTAIN-BUILDING
STRATIGRAPHY/ZONING AND CORRELATION ■ 117
erogenic period a period of mountain-building. See also p 132.
Caledonian {adj).relating to a period of mountain-building in Ordovician and Devonian times (p. 114), The general trend of the Caledonian structures is north-east - south-west.
Caledonides (n) the former range of mountains that was formed during the Caledonian orogeny (|), reaching from Norway to Scotland and Ireland.
Hercynian (adj) relating to the period of mountain-building that took place in late Palaeozoic times (p.114) in Europe.
Variscan (ad/)(1) = Hercynian (t); (2) relating to a period of mountain-building from the Carboniferous (p.114) to the Triassic (p.115).
Kimmerian (adj) relating to a period of mountain-building that took place in Jurassic times (p.115) in Europe.
Alpine (adj) relating to the period of mountain-building in the Tertiary period (p.115) that formed the Alps in Europe.
Taconic (adj) relating to a period of mountain-building that took place in late Ordovician times (p.114) in North America-Acadian (adj) relating (o a period of mountain-building that took place in ? late Devonian to end Permian times (p.114) in North America.
Appalachian (adj) relating to a period of mountain-building that took place in late Palaeozoic times in North America.
Laramide (adj) relating to a period of mountain-building that took place in late Cretaceous (? Jurassic) to early Eocene times (p.115) in North America.
synorogenic (adj) taking place at the same time
as a period of mountain-building, post-orogenic (adj) taking place after a period
of mountain-building, syntectonic (adj) taking place at the same time
as a period of deformation (p.122). synkinematic (adj) = syntectonic (t). post-tectonic (adj) taking place after a period of
deformation (p. 122). postkinematrc(>w'/) = post-tectonic (t)-
Tert.
v "1 ' ' 1
Caledonian Orogeny
4-
4
orogenies
biostratigraphicat (adj) a biostratigraphical unit is one that is based on fossils rather than on lithological (p.85) characters or on geological time. See also lithostratigraphical (p. 113), chronostratigraphical (p.113).
zone (n) a biostratigraphical (f) division: a strati-graphical division (p. 111) with characteristic fossils. One of the fossils present - the zone fossil - gives the name to the zone, zonal (adj).
hemera (n) a small unit of geological time as marked by the rise and fall of a particular species fossil. The word is not now in common use. hemeras, -ai, -ae (pi).
epibole (n) a stratigraphical term for the rocks deposited during a hemera (\), i.e., the time-rock unit corresponding to a hemera. The word is not now in common use.
correlation (n) in stratigraphy, the matching of racks of a particular age that are found in one place with other rocks found elsewhere. Fossils (p. 98) are generally used tor stratigraphical (p. 112) correlation, correlate (v).
provenance (n) the source area of the materials that form a sedimentary rock; the nature of the rocks from which it has been formed.
facies (n) (fades) the general characters of a sedimentary rock, especially those that indicate the environment (p.81) in which it was deposited.
lithofacies (n) a facies (f) that is characterized by a particular rock type.
biofacies (n) a facies (I) that is characterized by a particular assemblage (p. 100) of fossils.
diachronous (adj) 'across time'. A word used to describe a bed (p.80) or a stratigraphical unit that is of different ages in different places and cuts across the time planes.
Time
a diachronous formation
X is older a! A than al B