Word
Definition 1
Evolution
The slow ad gradual process of change over a log period of time that has given rise
to the diverse organisms around us today. This theory was first created by Charles
Darwin
Natural Selection
The process by which traits that make it more likely for an organism to survive and
reproudce. The traits become more common in a population over successive
generations Natural selection occurs because: 1) Variation existas within a
population of organisms. 2) All organisms face a daily struggle to survive and
reproduce, whether it is to find mates, to seek shelter, to find food or to avoid
predators. 3) Those organisms with features that best suit their environment have
the best chance of survival and reproduction. 4) Over time, the population will
become better suited to its environment.
DNA Hybridisation
Refers to a molecular biology technique that measures the degree of simalarity in
the DNA code of species.
Comparitive Anatomy
The study of similarities and differences in the anatomy of organisms.
Biogeography
The study of geographic distribution of a species using present day observations
and fossil records. Takes into account the existence of supercontinents and
Gondwana and Laurasia and how the developement of species during this period
evolved.
Gondwana
Southern half of the world. Opposite of laurasia
Pangea
The supercontinent that existed during the Paleozoic and Mesozoic eras
Sagittal Crest
Ridge of bone running lengthwise running along the middle of the top of the skull of
many mammals and reptiles
Neanderthal
An extinct human species or subspecies living during the late Pleistocene Epoch
throughout most of Europe and parts of Asia and northern Africa and associated with
Middle Paleolithic tools.
hominid
The group consisting of all modern and extinct Great Apes (that is, modern humans,
chimpanzees, gorillas and orang-utans plus all their immediate ancestors).
hominin
The group consisting of modern humans, extinct human species and all our
immediate ancestors (including members of the genera Homo, Australopithecus,
Paranthropus and Ardipithecus.
cro-magnon
An early form of modern human inhabiting Europe in the late Paleolithic Period and
characterized by a broad face and tall stature. Cro magnon is homo sapien.
Australopithecus
A genus of hominids that are now extinct. First human-like species present on Earth.
bipedal
Two footed animal
cranium
Top of the skull
foramen magnum
Hole for the spine underneath the skull
Homo
Man
fossil
The remains of a plant or animal that existed in the past that has been dug up from
the soil. There are several types of fossils depening on how they are formed e.g.
imprints, casts, moulds...
artificial selection
Selevtively breeding of an animal/plant for a desired characteristics/trait E.g. breeds
in dogs and other domestic animals have been created in this way.
palaeontology
The study of prehistoric life.
species
A common definition is that of a group of organisms capable of interbreeding and
producing fertile offspring of both sexes
adaptation
The variation in structure, form or trait of an organism that is most suited to the
environment. The trait can be either structural, physiological or behavioural.
homologous
Corresponding in structure and in origin, but not necessarily in function: The wing of
a bird and the foreleg of a horse are homologous.
species
A common definition is that of a group of organisms capable of interbreeding and
producing fertile offspring of both sexes
variation
Differences in structure, form ot trait that is recognised from the more common trait
analogous
similar or alike in function but not in structure and evolutionary origin e.g. fin in a fish
and in a whale.
era
A division in geological time
brow ridge
The bone structure above the eyes
Fossils
preserved remains or traces of animals, plants or other organisms.
Relative Dating
determining the age of fossils by the order of enents such as the order of rock layers
in the Earth. Fossils found in that layer are considered to be of the same age
Absolute dating / carbon
dating / radio-isotopic
dating
Determining the exact lage of fossils (by a number) from radioactive chemicals found
in matter (e.g. rocks)
Carbon dating
Using living matter (containing original carbon) to determine the exact date of the
material. As most fossils are formed by replacing of organic matter by sediments
fossils cannot be dated in this way.
coprolite
fossilised faeces
Missing Link
A transitional species i.e. a fossil that exhibits traits common to two different species
e.g. archaepteryx is a dinosaur (related to reptiles) that has bird like features and
believed to be a common ancestor of birds.
Direct descendent
They are directly related on the evolutionary tree.
common ancestor
A relation that is a direct descendent for both species on the evolutionary tree
characteristic/trait
Physical attributes of an organism
organism
A living thing. Can be animal, plant, animal or fungi
Sedimentation
The formation of fossils by the following process:
1)For a fossil to form animals or plants first fall into mud or silt in water to settle. Over
time, more layers of silt or mud, covered the remains compressing them between the
layer below and the one above.
2) TheThe lack of oxygen in the sediments prevents the fossil from decomposing.
Pressure from additional layers of sediment that formed above the remains
compressed them flat, forming an impression between the layers of silt.
3) Pressure and heat eventually changed the silt into layers of finely grained rock,
such as shale and slate, commonly called sedimentary rock. Over many centuries,
the matter in the remains was slowly dissolved, with the resulting space acting as a
mold that filled with minerals, preserving the impression as a fossil.
4) As time passed and the waters receded from geological changes, the once-wet
regions became dry land. Further geological changes exposed the rock surface,
making it possible to see the fossils within.
5) Many people hunt fossils in geological formations. Removing large sections of
rock, then split them along the layers, hoping to reveal the fossil of a fern, fish,
trilobite or other life that existed millions of years ago.
Convergent Evolution
when different species (organisms not closely related) have a similar trait
(analogous traits)
Divergent Evolution
when similar organisms (same species) have very different traits but the organisms
can be traced back to a common ancestor. (homologous traits)
Parallel evolution
when related species evolve similar traits but independently i.e. cannot be linked to a
common ancestor. This is usually because they have similar environmental
pressures.