Chapter 16-20 Flashcards
(66 cards)
1
Q
Define fossil
A
- anything that is evidence of life that lived long ago
- any preserved remains/traces of organisms
2
Q
General ways fossils are formed (4)
A
- drifting sand
- mud deposits (river)
- volcanic ash
- buried by another organism (burial)
3
Q
What are fossils generally made of? why/how do they consist of these materials?
A
limestone
ion oxide
- flesh rots away leaving a cast - minerals are deposited into the poor replacing the organic material
- becomes petrified and turned to rock
4
Q
Define petrified
A
Organic material that has turned into stone by replacing
5
Q
What are the (4) conditions for a fossil to be formed?
A
- buried quickly - to delay decay and deposits
- alkaline soils - ideal, means that minerals in bone don’t dissolve
- lack of oxygen - oxygen needed to decompose
- hard body parts
6
Q
General (3) locations for fossils
A
- edge of lakes, rivers - build up of sediments from flooding/flowing water over fossil to bury it
- caves - limestone containing of calcium carbonate - collapsed roof eg
- ash - volcanic eruptions which burry humans/animals
7
Q
Name of ppl who discover fossils
A
anthropologists
- find fossils of artefacts (tools, beads, carvings…)
8
Q
List 4 types of absolute dating
A
- potassium-argon dating
- carbon-14 (radiocarbon) dating
- Accelerator mass spectrometry (AMS) radiocarbon dating
- Dendrochronology (tree-ring dating)
9
Q
Potassium-argon dating use and description (what/process)
A
- volcanic rock only
- Isotope - different forms of the same element with different neutron numbers in nucleus of atoms
- potassium (K) - mixture of three different forms with different atomic weights
- isotope potassium-40 is radioactive and decays at a fixed rate - forms carbon-40 and argon-40
- determining amount of potassium-40 and argon-40 - can calculate age
10
Q
Limitations/restrictions/conditions for potassium-argon dating
A
- only volcanic rock
- older than 100,000-200,000 years - anything younger would have too little decay to determine
- require suitable rock of same age as fossil to be found
11
Q
Carbon-14 (radiocarbon) dating use and description (what/process)
A
- is the decay of the radioactive isotope (carbon-14 to nitrogen)
- young samples
- organic materials
- carbon-14 is produced in upper atmosphere where by cosmic radiation, turns to nitrogen at same rate it decays
- plants take in carbon (1 carbon-14 for every million -12) and animals eat plants
- when dead, -14 decays at a fixed rate, no more is taken in
- HALF LIFE - decays to half the amount after 5730 years)
12
Q
Limitations/restrictions/conditions for Carbon-14 (radiocarbon) dating
A
- younger samples
- up to 60,000-70,000 years
- 3g at least
- organic material
13
Q
Accelerator mass spectrometry (radiocarbon) dating use and description (what/process)
A
- more refined
- dates small samples - as small as 100 micrograms
- breaks up sample into its atoms so they can be counted
- for cave paintings eg - pigments, honey, charcoal, oil, blood
- for artefacts - tools, fire charcoal
14
Q
Limitations/restrictions/conditions for Accelerator mass spectrometry (radiocarbon) dating
A
- very small fossils
- 100 micrograms +
- recent - younger than 60,000 years
must contain carbon - organic material
-14, -12 ratio is not constant
15
Q
Dendrochronology (tree-ring dating)
A
- Using tree rings to determine years
- Each ring represents one years growth
- Rings vary in width compared to favourability of growing season
- Correlate marker rings with timber taken from ancient human structures - determined age of these human structures
- Small sample drilled from trunk and counting rings
- Combined by radiocarbon dating
16
Q
Dendrochronology (tree-ring dating) limitations/restrictions/conditions
A
- Only determine age of tree/wood
- Timber is rarely preserved for more than a few thousand years
- Necessary conditions rarely occur
- Up to 9000 years old
17
Q
List 3 types of relative dating methods
A
- fluorine dating
- phylogenetic trees
- stratigraphy
18
Q
What is stratigraphy
A
- study of layers of strata
1. Principe of superposition - assuming that top layers are youngest - are complications though
2. Correlation of rock strata - matching layers of rocks from different areas - examining rock itself first then fossils in it
19
Q
Define index fossil
A
widely distributed - on earth for a limited period of period
20
Q
Materials found with stratigraphy
A
bones, teeth, petrified wood/log, coral, insects, trilobite
21
Q
Limitations of stratigraphy
A
- Natural disasters - tsunamis
- Earth plate movements
- caution because sometimes layers are turned upside down - sometimes humans or animals are buried after deposition - may actually be younger than layers above
22
Q
What is fluorine dating
A
- When bone is left in soil, fluoride ions present in the water in the soil, replace the ions in the bone
- The older the fossil, the more fluoride it contains
- Not absolute because fluoride in water in soils varies from place to place
23
Q
Define binomial system
A
- use generic (genus) and specific (species) name
24
Q
Define
A
evolutionary trends - gradual change in characteristics that occurred as primates became more highly evolved
25
Define hierarchy
- series of groups of species from broad to specific
| - divided into orders/ groups known as phyla
26
2 types of primates
primitive and anthropoids
27
Define arboreal
living in a tree environment
28
List 8 general characteristic of all primates
- BODY - not specialised for anything particular
- LIMBS - unspecialised
- HANDS/FEET - pentadactyl (five fingers), nails instead of claws, prehensile (grasp), first digit opposable,
- EYES - 3D, forward facing, colour
- SMELL - poor
- TEETH - four incisors in upper and lower jaw
- BRAIN - large and complex, cerebrum size is larger
- REPRODUCTION - not restricted to a breeding cycle, rhythmic sexual cycle - month, year, One offspring at a time , Long period of parental care
29
List 5 evolutionary trends (NOT for erect posture)
- digits, dentition, smell, vision, brain, gestation/development
30
Digits - list 6 evolvements
1. pentadactyl
2. prehensile
3. opposability
4. nails
5. friction ridges
6. precision grip
31
Describe 'prehensile' as a trend
- grasping fingers
| - Evolutionary trend is to be able to move them freely of each other
32
Describe opposability as a trend
- thumb can touch each finger - longest in humans
- Toe is opposable in primates -- BESIDES humans - lost due to weight baring
- Degree varies between species
33
Describe nails as a trend
- shorter and flattened instead of claws
- Secure grip on trees
- Better grip on objects
- Some have single claw - toilet claw for scratching
- Receptors on tips
34
Describe friction ridges as a trend
- small pads with tiny ridges/folds to increase grip
35
Describe precision grip as a trend
- only in humans
- For holding pencils and sewing etc
- Precise, delicate movement
36
List 5 dentition evolvements
1. change in dental formula
2. dental comb
3. number of teeth
4. diastema
5. cusps
37
Describe dental forumula as a trend
- number of each type of tooth
- Primitive mammals - 3:1:4:3 (3 incisors, 1 canine, 4 premolars, 3 molars) - Total of 44 teeth
- 36 teeth in lemurs, lorises and new world monkeys
- Human teeth - 2:1:2:3
- Total of 32 teeth
38
Describe 'number of teeth' as a trend
- Decrease in number of teeth - smaller face/head
| - Large, sharp, pointy canines in old world monkey - humans are similar to other teeth
39
Describe diastema as a trend
- human don't have anymore - change I diet and survival requirements
- gap between large upper and lower canines
- makes room for large incisors
- Premolar slants to give room for large incisors
40
Describe cusps as a trend
- evolve from 3 cusps to 4 in top molars (+ shape)
5 cusps in humans now
- 5 cusps in lower molar (Y shape)
- Evolved due to change in diet - fruits
- Layer of had enamel covering teeth for protection from decomposition
41
Describe dental comb as a trend
- horizontal tooth bottom for grooming
| - has disappeared now
42
List and describe 4 trends in vision
1. olfaction - decreased smell segment and increase emphasis on vision section in brain
2. Stereoscopic vision - eyes at from of head - moved forward
- was mandatory when arboreal - judge distance between trees
3. Eye socket - become enclosed to protect the larger nerve
4. Rods and cones - night vision and colour - Improved nerves between rods, cones, and brain
43
Discuss 'relative size of cerebral cortex' as an evolutionary trend
- increased in size
- SIZE, CONVOLUTIONS, CEREBRAL SIZE
- Involved with higher functions - vision, memory, reasoning…
- Human average size - 1350cm3
- Larger brains in primates for;
- coordination as arboreal
- Special/social skills
- Finding food
- Identifying threats
- Larger and rounder with bigger brain and intelligence
- Convolutions - stronger pattern/more in humans
44
Discuss 'Gestation and parental care' as a trend
- Increased length between fertilisation and brith
- Increasing length that offspring is dependent off parent
- sexual maturity increasingly later development
45
State name for walking stance /motion
upright bipedal locomotion
46
Define tribe
given to relatively new level of classification
47
Brief order of primates (5) oldest to youngest
1. Australopithecus africanus
2. Australopithecus afarensis
3. Homo erectus - standing upright
4. Homo neanderthalensis
5. Homo sapiens - humans
48
List 8 adaptations/trends for erect posture
1. foramen magnum
2. curvature of the spine
3. jaw
4. pelvis
5. carrying angle
6. knee
7. foot
8. centre of gravity
49
Compare the foramen magnum position / neck between apes and humans as a adaptation for erect posture
APE
- sits at back of skull - horizontal stance
- have large, strong neck/muscles to carry/support head
HUMANS
- sits in the centre of the bottom of the cranium
- in line with centre of gravity
- supported by vertebrae column
- has gradually moved forward because of erect posture
50
Compare the curvature spine between apes and humans as a adaptation for erect posture
APE
- flat, slight curved spine
- straight
- head protrudes off
HUMAN
- double curvature (two curves)
- S - shape
- CTLS / "STILTS" - cervical, thoracic, lumbar, sacral
- wedge of the lumber gives from froward to back - gives jutting curve
^ enables balance on neck
- brings vertical column directly under centre of gravity of skull
51
Compare the jaw between apes and humans as a adaptation for erect posture
APE
- protruding
- large size
- U shape
HUMAN
- flatter facial profile
- to balance head in the centre - so that head isn't sticking out front/back more
- parabolic shape
52
Compare the pelvis between apes and humans as a adaptation for erect posture
APE
- elongated
- narrow
- consists of scrum, acetabulum, pelvis
HUMAN
- broader and shorter
- bowl shaped
- supports abdominal organs
- larger in women for passageway in birth
- space for bone and muscle attachment
53
Compare the carrying angle between apes and humans as a adaptation for erect posture
APE
- swayed walking
- acetabulum in light with inner knee joint
HUMAN
- tip of hip joint (hook) is directly above the centre of the knew joint - so busy weight can be transferred from pelvis to leg
- wider acetabulum = femur converges towards inside
- weight falls on outside of knee
- centre of gravity crosses over femur
- striding gate - hips and knee can be fully extended
54
Compare the knee between apes and humans as a adaptation for erect posture
- knee is a hinge joint with ligaments on either side
- centre of gravity is in line with front of knee and down the outside
- therefore force is trying to pull knee back but ligaments restrict bending in opposite direction
= hinge wants to bend forward - force wants to bend back = equals out for no energy
55
Compare feet between apes and humans as a adaptation for erect posture
APE
- able to grasp with foot
- opposability of big toe
- lower down and smaller big toe - not as big and important as humans for balance
HUMAN
- lost prehensility (grasping)
- big toe is large and aligned with others - for balance
- metatarsals for arch's -longitudinal (front to back) and transverse arch (side to side)
56
Compare centre of gravity between apes and humans as a adaptation for erect posture
APES
- longer arms than legs - brings upper body down/slouched
- higher centre of gravity - chest region
HUMAN
- longer legs - concentrates gravity, increases length of stride/steps
- lower centre of gravity - hips/pelvis
57
Describe muscle tone in 3 areas
1. striding gate - weight transferred from heel, along outside, crossing the ball and finishing at big toe
- foot is now weight baring not gripping
2. arm swinging - compensates for trunk rotations around pelvis
- Right arm swings at left step etc.
- Reduced energy expended
3. carrying angle - weight distribution towards central axis
Rotation of body at lower leg and foot - each footstep is more straight
58
Describe relative size of cerebral cortex as an evolutionary trend
- 1350cm3 - average human
- frontal lobe in humans is very large - think, planning, processing, reasoning
^ functions that don't occur hugely in app
- absence of forehead in apes & protruding brow bone
- cranium capacity measures brain size by endocasts
59
Prognathism & dentition as an evolutionary trend - APE VS HUMAN
APE
- protruding canines which are large and pointy
- dental arcade = U - shape
- diastema
- 2:1:2:3
- large brow ridge - instead of frontal lobe
HUMANS
- small canines - look like incisors
- parabolic shape
- 2:1:2:3
- small brow ridge
60
List 5 advantages of bipedal locomotion
1. increase range of vision - food/predators
2. increase in height - scaring predators
3. hands free for carrying (food)
4. higher reach
5. improved body cooling
61
Why was there evolution from ape to bipedal locomotion/erect posture? (general)
- cooling
- 5 survival advantages
- change in climate
- change in environment - thinning of forests etc
- avoid over heating - less sun contacts with vertical stance
62
Australopithecine first fossil origin and time period
Southern Africa
| Early 1920s
63
Australopithecine - first noticeable changes (8)
1. brow ridge / lower forearm head
2. rounder head
3. less protruding jaw
4. . less protruding teeth
5. foramen magnum moving forward
6. bipedal locomotion
7. canine
8. pelvis/femur
64
Name/ briefly describe two variants of australopithecines
1. robust - taller and heavier
- large, broader molars & jaw
- bony crests in skull
2. Gracile - shorter, lighter
- proportioned head & jaw
- Australopithecus afarensis and Africanus
65
What is the other name for homo habilis - why that?
handyman
66
Features of homo habilis (5)
1. larger brain
2. smaller teeth
3. taller
4. stood more erect
5. powerful grasp- still spent time in trees
