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relatively rapid expansion and diversification of an evolving group
of organisms as they adapt to new
Adaptive radiation is the process by which one species evolves into
two or more species. This occurs as a result of different
populations becoming reproductively isolated from each other,
usually by adapting to different environments.
- any animal of the primate suborder
Monkeys, apes, and humans are the living anthropoids.
- tree-living; referring to animals
that are adapted to life in the trees. Arboreal animals spend most of
their time scampering around in trees rather than on the ground, in the air,
- members of any species of the genus
Australopithecus. They lived during the Pliocene and
early Pleistocene geological
Epochs in Africa (i.e., ca. 4.2-1.2 million years ago).
Australopithecines and humans
One or more species of australopithecines probably were our ancestors.
two-footed, upright form of locomotion typical of
walking is an example of bipedalism.
- the comparatively pointed teeth on
either side of the incisors, at the front of the mouth of mammals. There is one
canine tooth in each of the four quadrants of the mouth. Canine teeth are mainly
used to pierce and tear food.
- a space or
gap between the canine and adjacent teeth. It allows room for
the point of the protruding opposite canine tooth and thereby
permits the upper and lower teeth to bite together.
Normally, there is a diastema opposite each of the four canine
teeth if the canines are significantly longer than the other teeth.
- the most recent
geological era, dating from about 65 million years ago to the present.
It is the era in which the mammals flourished. It began as the last
dinosaurs became extinct, at the end of the
Era. Most of the placental mammals and all of the primates evolved
during the Cenozoic.
- a date that places an event in its
chronological position with reference to a universal time scale such as a calendar.
Such dates usually are given in terms of the number of years before or after a calendar
starting point. For instance, 1950 B.C. was 1950 years before the beginning date of
the Gregorian calendar, which is commonly used
today. See relative date.
- a term referring to teeth.
micro-habitats in nature to which populations or organisms adapt.
They are usually seen in terms of being food getting opportunities
in the environment.
genetic change in
of organisms that occurs over time. The term is also frequently
used to refer to the appearance of a new species. More specifically, it
is change in the
frequencies of alleles in a population's gene pool
from one generation to the next.
flora and fauna
- terms of
Latin origin that are commonly used in the sciences to refer to the
plants (flora) and animals (fauna) in an environment.
- the hole at
the base of a skull through which the spinal cord passes.
Literally, foramen magnum means
a "large hole or opening" in Latin. The position of the
foramen magnum is a strong
indicator of the angle of the spinal column to the head and
subsequently whether the body is habitually horizontal (like a
horse) or vertical (like a monkey).
- a group of
closely related species. In the Linnaean classification system,
genus is the category immediately above species.
- a dramatic reduction in genetic diversity of a
population or species resulting from an ecological crisis that wipes out most
of its members.
The limited genetic diversity of the few survivors is the pool from which all
future generations are based. This phenomenon is also referred to as a
- graceful, slender, and delicate.
This 17th century English term is used to describe the body characteristics
(especially bones) of the
and the earliest humans.
Great Rift Valley
- a long depression in Southwest Asia
and East Africa caused by the movement of
largely beginning during the Oligocene Epoch. In
Africa, it extends from Ethiopia southwest 1200 miles through the lake regions. Many
of the early hominid sites are in this valley system.
- eating only vegetable
foods. Animals that have this sort of diet are herbivores or
vegetarians. See carnivorous and
- any species of the primate family
Hominidae. The gorillas, chimpanzees, bonobos, australopithecines, and humans are hominids.
- any species of the
primate tribe Hominini. The
australopithecines and humans are
- any species of the primate
superfamily Hominoidea. All
hominids and apes are
- a class of warm blooded, usually
hairy animals, that feed their young with milk secreted by the mammary glands of
females. The Mammalia include
marsupials, primates, cats, dogs, bears, hoofed animals, rodents,
bats, seals, dolphins, whales, and several other groups of animals.
geological era immediately preceding the
and dating approximately 251-65.5 million years ago. The Mesozoic
was the era in which the dinosaurs flourished and the first
mammals and birds evolved. Note: some geologists suggest that
the Mesozoic most likely started 245-248 million years ago.
- the infraclass of
mammal species in which females bear their young in an immature condition (while still in
the early fetal stage) and then permit their further infant development in an abdominal
pouch covering their mammary glands. Compared to the delayed births of
placental mammals, this is inefficient in keeping young
infants alive. Metatherian mammals are also called marsupials. Included in
this infraclass are kangaroos, koalas, opossums, etc.
- the fourth
geological epoch of the
Cenozoic Era. The Miocene occurred approximately 23-5.3 million
- the comparatively large grinding
teeth at the back of the mouth in mammals. In
all other anthropoids, there are normally 3 molars in each
quadrant of the mouth.
- an evolutionary
mechanism that occurs when some individuals of a population are better able
to adapt to their environment and, subsequently, produce more offspring.
Nature, in effect, selects which members of a population are fit to survive
long enough to reproduce. Differential productive success between
individuals is the key. Those who produce more offspring have a
greater influence on the gene frequencies of the next generation. This
mechanism of evolutionary change was first articulated by Charles Darwin.
- the most well known late archaic
Homo sapiens. They lived mostly in Europe and the Near East from
150,000 years ago or even earlier until at sometime after 28,000 years
ago. There is an on-going debate as to whether they should be
considered Homo sapiens or a distinct but related species. If
they were members of our species, they were a different variety or race
(Homo sapiens neanderthalensis). On the other hand, if they were
different enough to be a distinct species, they should be considered to
be Homo neanderthalensis.
- the third geological epoch of the
Cenozoic Era. The Oligocene occurred approximately
33.9-23 million years ago.
- members of the
hominin genus Paranthropus
described first in the 1930's by
Since the 1960's, most paleoanthropologists have not classified them
as a separate genus but, rather, as members of the genus
Australopithecus. From this perspective, the
paranthropoids were the robust australopithecines. They lived during the late Pliocene and early Pleistocene
geological Epochs in Africa (i.e., ca. 2.5-1.2 million years ago). .
- The pelvis consists
of the bones in the hip region. The upper leg bones (i.e., femurs) connect
to the torso at the pelvic girdle and the spinal column ends there as well.
- the fifth geological epoch of the
Cenozoic Era. The Pliocene occurred approximately
million years ago. The australopithecines and earliest humans evolved
during the Pliocene Epoch.
- the teeth with two-pointed crowns
located between the molars and the
In hominids, apes, and all Old World monkeys, there are two premolars in each
quadrant of the mouth. The premolars are also called bicuspids
- members of the suborder of
) that includes all of the lemurs, lorises, and related
- a four-footed form of locomotion.
Most mammals are quadrupeds. The
are exceptions, being bipeds.
- referring to techniques for
chronometric dating based on known half-lives of particular
isotopes or the rate of other cumulative changes in atoms resulting
from radioactivity. Examples include electron spin resonance, fission track,
potassium-argon, radiocarbon, and thermoluminescence dating.
- a date that
gives the time of an event only with reference to another event that
is not worldwide in scale. It only indicates that one event
occurred earlier or later than another. For instance, the
observation that strata 2 is younger than strata 1 beneath it in a
geological deposit does not provide information about how many years
ago strata 2 was laid down. It only indicates its age relative to
strata 1. In addition to the use of stratigraphy,
relative dating methods include biostratigraphy and fluorine
analysis dating. See
- a term used by paleoanthropologists
to refer to a big boned and muscular body. The robust species of early
hominids were Australopithecus robustus, boisei, and
- a ridge of bone projecting up, from
front to back, along the top midline of the skull. It serves as a muscle attachment
area for the temparalis muscles that extend up both sides of the head from the mandible
(jaw). The presence of a sagittal crest indicates that there are exceptionally strong
jaw muscles. Some Australopithecus afarensis and the robust
robustus, boisei, and aethiopicus)
had sagittal crests. Among the living primates, the most prominent
sagittal crests are found on adult male gorillas. Humans do not have them.
- a tropical
or subtropical grassy plains.
Savannas are usually the habitat of larger herbivores and their
predators. The first
hominids apparently evolved on and near African savannas.
- referring to anatomical
differences between males and females. Primate males are usually significantly
larger and more muscular than females.
- the study of the earth's crustal
structures, such as continental plates, and the forces that cause them to change shape and
move relative to each other.
- a bony arch extending horizontally
on either side of the face just below the eyes on primates and many other vertebrates.
The major jaw muscles pass under these two arches on their way up to the temporal
areas of the skull for attachment.
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