Lecture 6/7 Flashcards
provenance
the original location of a fossil artifact - must be done before identifying time frame
Relative dating
method of dating that identifies fossils as being young/older of other known artifacts or objects
- doesn’t assign exact age
Stratigraphy (Strata)
method of relative dating
- study of different layers (strata) that have been deposited over time
- works well with sites that haven’t been disturbed
law of superposition: within undisturbed geological deposits, strata are laid down from oldest to most recent
- this is reversed in sites of erosion, materials that are found in the water are on top, but they are oldest
- fossils buried lower in the strata are older than those buried closer to surface
- alterations from geological process such as folding and uplifting disturb a site
Biostratigraphic dating (faunal correlation)
faunal: Animals, especially the animals of a particular region or period, considered as a group
- dating a fossil based on association of faunal remains that have been securely dated using other methods
- primate fossil found with remains of extinct species of pig known to have lived 35-40mya -> association = fall into the same range of time
Flourine dating
relative dates based on amount of fluorine in bones
- bones and teeth absorb fluorine when animals dies from surrounding ground water.
- more amount of fluorine present = older specimen
Absolute dating methods (Chronometric)
assigns a specific age and estimated error to a fossil or site
associated with dating error +/- differing from the actual day
Radioactive isotopes
unstable isotopes that decay, emitting radioactivity
decay at a constant rate into more stable forms
Radiometric dating
absolute dating method using radioactive decay of the isoptoe c14 into N14
- all living organism posses C14 from the environment
- when they doe it stops taking in C14 and turn it into 14N
- c14 has a half life of 5730 years +/- 40 years
- use to date organic materials: wood, bone, charcoal
- only usually for dating past 40,000 to 45,000 years ago
Potassium-Argon dating
absolute dating to measure decay of K40 into argon gas Ar40
K40 has a half like of 1.3 billion years
- used for dating volcanic material - and not dating fossils you are dating time of events
Atomic mass spectrometry
method of radiocarbon dating used to date very small samples
Geological Times scale
evidence of climate change, precise radiometric dating
- division of the earls geological events into time periods such as eras and epochs. Based on temporal divisions defined by features of fossilized remained of extinct organisms
Epoch
measure of geological time that partitions geological eras into smaller units, defined with regard to major climatological/environmental events
Cenozoic era
included mammals and emergence of primates
Oxygen isotope analysis
stable oxygen isotopes to reconstruct ancient climates using ice cores taken from polar icecaps and sediment cores taken from ocean floor
looking at ratio of O18 and O16
O18 is heavy so when water evaporates it gets left behind and makes sea water a high ratio
glacial period have O16 locked in, a low ratio = cold periods
ice cores with high ratio were warmer periods
Crown group
last common ancestor of a clade plus all of its descendants including living members of the clade
stem group
extinct organisms that are not part of the crown group
Paleocene
Plasidapiforms and flowering plants!
After extinction of the dinosaurs and less proliferation of gymnosperms
first epoch of the cenozoic era
warmer climate which allowed for angiosperms to proliferate
primate like mammals with a low dental formula of 3.1.4.3, large procumbent (forward-facing) incisors, long snout, laterally facing orbits, claws, no post-orbital bar
- diet of insects and fruits
Eocene
Strepsirhines and start of haplorhines
First euprimates - lemurs and lorsises
- very warm climate, tropical all over NA, africa, europe and asia
- foreword facing eyes, post-orbital bar, reduced snout
Omomyidae: tarsier like primates
- small, large eye orbits to be nocturnal, lack of tapetum, elongated calcaneus to leap branch to branch
- teilhardina asiatica found in china
Adapids
- lemur like primates
- larger than omomyids, larger snout, smaller eyes, teeth suggest leaves and fruit diet
Darwinius masillae
- small, arboreal quadruped that is debated to be either a strepsirhines or a haplorhine
Eosimias
- found in china
- looks alot like darwinius masillae
- tree-dwelling primate
- displays tarsier (omomyid) like features like the ankle bone
Tapetum:
reflective layer behind the retina that increases the light capturing capacity of the eye
- omomyids do not have this, the large eye orbit allows for the extra light to allow them to still be nocturnal
Oligocene
Anthropoids: Oligopithecidae, Parapithecids, Proliopithecis
Temperature dropped significantly - reduction in forest, extinction of many land mammals in europe
- Fossils all found in the Fayum depression in Egypt (very small area of land)
- includes haplorhines and strepsirhines
Oligiopithecidae
2.1.2.3
ancestor to catarrhines - Old world monkeys
Paralithecidae
2.1.3.3.
ancestor to platyrrhines - new world monkeys
low rounded cusps - fruit eating
small eye socket - diurnal
post cranial skeleton gives quadrupedal mode
Proliopithecidae
2.1.2.3
ancestor to catarrhines - old work monkeys
dimoprhic canines which shows variety in mating system
type: aegyptopithecus: very large 6-8kg
y-5 patterns on lower molars
sagital crest which shows lots of chewing - leaves in diety
large brain
New world monkeys
2.1.3.3.
Platyrrhines
Found in South America
Hypothesis: NWM arose from African anthropoid and spread to south america by rafting across southern atlantic on floating masses of vegetation
Oligocene had low levels of sea water so there were islands to make this possible
Morphological similarities between african and south american anthropoids to support hypothesis
Carpolestes simpsoni
Plesiadapiform in Wyoming
Old word monkeys
Egypt, Libia, Kenya
colobines and cercopithecines
sexual dimorphism
2.1.2.3
Miocene
Planet of the Apes - hominoids
Temperatures increased again to be tropical
- Early Proconsulids: forest and woodland environments of africa
10-50kg, no tail, larger brain relative to body size, front and hind limb of equal length and limited wrist and shoulder region
Y-5 patterns on molars
diet: soft fruit
Middle Miocene
climate cooled again, sea levels dropped, decrease in forest
Bridge between Africa and Europe/Asia
Robust mandibles, large flat molars with thick enamel - indicating diet of hard food
Dryopithecus
- 17 mya
- Edward Lartent in 1856
- found in europe
- larger than earlier apes, large canines, detention suited for fruit
- teeth grew slow - long life span
Pierolapithecus catalunicus
spain
13 mya
Salvador mona-sola and Meike kohler in 2002
Late Miocene
a little colder and drier, decrease in forest, increase in grassland - hominoids move from Asia to SEA Sivapithecus - pongine - found in Asia - 12-8mya - resembles modern day orangutang - projection premaxilla, narrow nasal bones, oval eye orbit chimp resemblance post-cranial skeleton Gigantopithecus - 8-0.5mya - Blacki - very large asian ape - 300kg and 3 meters tall - terrestrial - not related to orangutang
Paleoanthropology
study of human origins
collaborative study that involves geologist, palaeontologist, palynologists and anthropologists
Neanderthal discovery
1829, but 1856
Darwin
suggested that human origins lay in Africa
Eugene Dubois
was uncovering evidence of early humans in SE Asia for the missing link from Ernst Haeckel
pithecus = ape
anthropus = man
erectus = erect
Older remains were found in
Europe
older than the Neanderthal man
Pitldown Hoax
charles dawson - uncovered what appeared to be human remains
human cranium, and a chimp mandible, strange orangutang’s teeth
thought he found the missing link between ape and man
went on for 40 years from 1912-1949
radiocarbon dating was used to discovery this was a hoax in 1953
Johan Anderson
Swedish geologist worked with chines national geological survey
- wrote a book called children of the yellow earth
- cave where he found lots of human remains that had been occupied several times over by human ancestors
- human origin was likely to be in Asia from this discovery
- Describe Yangshoa culture which was found along the yellow river
- Found Zhoukoudian - same species as eugine dubois found - homoerectus
Raymond Dart
Taung child specimen
found in 1924
specimen had a child like cranium so it was hard to identify because it could grow up into any type of primate, it could have had that variation due to ontogeny
Dated it back past homoerectus in SE Asia
Robert Broom
1936 went to Sterkfontein in Africa
Australopithecus africanus
Had found a cave in sterkfontein that had fossils of leopards, primates, and ancestors
Found adult specimen of human ancestors and now is the oldest specimen of human origin
Louis Leakey
Inspired by Raymond and Robert to look in Africa
looked for geological formations that have greatest likelihood for fossil bearing for emergence of human ancestors
East African Rift Valley: kenya, Ethiopia, and sudan
- studied modern day primates to serve as a good analogy for inferring behaviour in the past
- data yielded evidence for hominoids in East african rift valley
Mary Leakey
1948: found intact skeleton of a proconsulid
1950s: robust form of australopithecus
Chronology and Telling time
- time if often linear for paleoanthropologists, consisting of a sequence of events that are arranged and ordered in a time line
Terminus Post Quem:
suggest subjects are younger than the event
- earliest possible date for something
Terminus Ante Quem
subjects are older than the event
latest possible date for something
Law of Superposition
a law in natural sciences that stipulates that geological layers are deposited in a time sequence with oldest at the bottom and younger at the top
reversed: erosion the loose materials by the water is reversed, fluidity born materials -> older even though they are on top
Seriation
Oscar Montelius
Aims to arrange objects based on physical attributes into an order that produces meaningful patterns, most often used to produce relative ages of artifacts compared to others
when people manufactured specific materials, we are able to tell using seriation and we can correlate these dates with other material things
all humans creations change through time
ex: toothpaste, if you find a toothpaste tube you are dealing with after the 1870s.
Used to tell relative time, not absolute
Absolute Carbon Dating
Willard Libby
1949
looking at ratio of c12:c14 found in a dead organism
Has to be calibrated because atmospheric ratio stays the same thoughout time, but ocean water has higher levels of C14 so if an organism drinks out of the ocean it will have more C14 in its body and will be dated later.
Assumption: production of c14 must be constant and there must be no introduction of other c14
Nuclear Testing
caused us to not be able to date before 1940’s because of the amount of c14 it altered in the atmosphere
Deandrochology
Andrew E. Douglas in Arizona
tree rings
1) can be used to obtain absolute and calendrical dates
2) can be used to determine paleoclimates
3) can be used to calculate radiocarbon dates
when different tree dates overlap they will respond to the environmental pressures the same and have the same pattern of tree rings
can be used to calibrate radiocarbon dates because they are organic material so you can carbon date them
- check if any environmental changes altered the amount of c14
Potassium Argon
measure decay of K40 to Ar40
half life of 1.3 billion years
volcanic materials - molten rock will become solid from it’s liquid form and when it hardens we can measure the decay of K40 to AR40
you can date very old material but you cannot date young
dating -> you are dating a geological event, not material
only effective on volcanic rock formed before 100,000 years ago
Wiggle room
gap between 40,000 and 100,000years ago we dont have a method to date during this time so it is difficult to date and be precise
Lumpers
less speciose less bushy tree
Splitters
Speciose
classify new species, drawing distinctions to new species like behavioural patterns
Because we are only looking at fragments of fossils, reconstructing past phylogenies can be problematic and continuous
Only a small fraction of material fossilize and preserve itself
Must extrapolate relationships and morphological structures between species
First Mammals
Therapsida
251MYA
mammals evolved in early jurassic period
Gymnosperms: plants that reproduce without flowering seed, the seed is not in the ovary
- conifers, yews, and gingkos
Extinction
Wiped out dinosaurs and changed the floor plan of earth
decrease in gymnosperms and increase in angiosperms (flowering plants)
organisms had room to proliferate because there was a decrease in competition, the survivors took on no ecological niches
Angiosperms started to cover boreal environments - trees, bushes, forests
End of Mesozoic era - start of Paleocene
Paleocene
Plesiadapiforms and Angiosperms
warm weather
plesiadapiforms were primate like mammals that were probably what primates were derived from
Angiosperms - provided arboreal food for primates
Arboreal Hypothesis
Sir Graton Smith and Frederick Jones
1905
primates evolved because as the forests became modified there was more ecological niches developed up in the canopies
need nails to not get in the way of grasping, retention of clavicle to go branch to branch, stereoscopic vision to see next branch, and 5 digits
problem: there are other organisms and mammals that live in trees that don’t have these adaptions and survive
Visual Predation Hypothesis
Matt Cartmill
1970s
Earliest primates were insectivores, need to snatch and hold onto insects, need good vision to spot insects and move quickly through the canopy
problem: Earliest evidence says that primates were not insectivores based on dentition
Angiosperm Radiation Hypothesis
Robert Sussman
1980s
Primates need to see the plants in color, thrive in arboreal terrestrial environments, see fruit and be able to pick it
Environmental selective pressures need primate adaptation to be beneficial
Carpolestes Simpsoni
Wyoming 60mya Fruigivore dentition opposable grasping toe with nail no foreward facing eyes Claws on from limbs Can't judge distance without stereoscopic vision so is this a plesidapiform or is it a primate?
Eocene
Strepsirhines (Euprimates) First true primates
56-34mya
temperature was very warm - tropical, proliferation of arboreal environments and primates
Teilhardina asiatica - looked like a tarsier (omomyid) - looks more like a haplorhini, which did not proliferate at this time, but start to emerge
Eosimias - fossil found that looked like a haplorhini, because it had a short calcaneus (ankle bone) - found in china
Darwinius Masillae -very similar to eosimias
- found in messell pit in 1983
Omomyids: Tarsiers
- small body, large eye orbit, long calcaneus
Adapids: Lemurs and Lorises
larger than omomyids
large snout, small eye orbit, small of teeth indicate leaves and fruit
Oligocene Primates
Anthropoids: Olgopithecids, Parapithecus, Propliopithecus
34-23mya
cooling
All fossilized material in the Fayum Depression of Egypt
Major geological and climate change. NA and europe separated, india drifted into Asia, primates gradually disappeared
Oligopithecids
2.1.2.3.
catarrhines - old world monkeys
Parapithecids
2.1.3.3.
platyrrhines - new world monkeys
primitive haplorhines
Propliopithecids
2.1.2.3 catarrhines - old work monkeys type: aegyptopithecus Zeuxis - very large propliopithecids - large sagital crest and relatively large brain
New World Primates
platyrrhines
2.1.3.3.
hypothesis that they got to South america from Africa via the Southern Atlantic via a floatation device
Miocene
Hominoids 25-5.3mya Proconsulid: Dryopithecids, Sivapithecus, Gigantopithecus similar to oragnutangs, gorillas, and chimps Features: - reduction of lumbar region - no tail - brachiation - suspensory locomotion - longer gestation periods - folivores (leaf eating)
Proconsulids
2.1.2.3 (OWM - catarrhines)
proconsul major: large ape size of modern day chimp - 50kg
1909: Louis Leakey
reduction of lumbar region
front and rear limbs of equal length - more carpals articulated directly with ulna which limits wrist mobility
- Y-5 molar pattern
Morotopithecus bishopi
Flexibility of hands
skeleton suggest flexible shoulder joint and a femur poorly adapted to quick arboreal locomotion
less primitive, later in time, in east Africa
Dryopithecus
Edward Lartet
1856 found in Europe
lived 17mya
larger than earlier apes with large canines and dentition for fruit
longer life span due to slow teeth growth
partly terrestrial primates due to being larger - they are subject to predation
another type found in spain
Sivapithecus
Found in Asia 12-8mya share similarities with modern day orangutang - projecting premaxilla, narrow nasal bones, oval eye orbit resembles chimps post orbital skeleton type: indicus
Gigantopithecus
8-0.5mya large asian ape 300 kg and 3 meters tall terrestrial Type: blacki
Lithostatic Pressure
reconstructing human, primate, and hominid taxonomy and phylogeny
pressure exerted on a layer, object or artifact by the weight of overlying sediment or deposits that mishaps or distort it
• if it received that pressure before it was buried entirely
• moisture will cause warping
• pressure over time (fossilizing) will cause it to be distorted in a smooth way, no cracks, no impact related trauma
Taphonomic processes
process of fossilization, you should consider
1) most fossilized remains do not remain intact - often only finding fragment
2) not looking at actual bone because it has been fossilized, so even size is not accurate there could be swelling or retraction
3) Fragmentation due to fossilization process
4) Distortion of element -> lithostatic pressure (no cracking just warping)
