Biological Anthro EXAM 3 UARK Delezene

Taphonomy

the study of what happens to an individual after death

Geological Principle of Superposition

Low strata = older
High strata = younger

Fossil

the preserved remains, impressions, or traces of past organisms

Relative Dating

arranges geological events with the stratigraphy method (high or low strata), doesn't provide numerical dates

Absolute Dating

determination of objects based on measurable qualities (exact)

Radioisotopic Dating

Fossils and carbon are the same age in strata

What is a half-life?

the time radioactivity takes for an isotope to fall to half its value

How is the radioisotopic decay of isotopes used to "date" fossils?

by heating up the fossils to see how much carbon is in them because in one half life half the carbon will have decayed

If i tell you that the half life if 14C is 5730 and that a bone found in a cave has only 1/4 of the original 14C remaining, how old is the bone?

11,460

if it was asking for 1/8 = 17,190
1/16 = 22,920
1/32 = 28,650

How do we use changes in magnetic polarity to check the absolute dates assigned to fossils?

the higher the polarity the older it is

Depositional Enviroments

- Fluvia - rivers
- Lacustrine - lake deposit
- Caves - Blombos is the most important, associated with homo sapiens
- Karst Systems - a region made up of porous limestone containing deep fissures, caves, and streams

Cenozoic Era

Paleocene (65-54 MYA)
Eocene (54-34 MYA)
Oligocene (34-23 MYA)
Miocene (23-5.5 MYA)
Pliocene (5.5-1.8 MYA)
Pleistocene (1.8mya-10kya)
Holocene (10kya-today)

Adapids

Epoch: Eocene
Body size: small
Diet: frugivores & folivores

How does this niche differ from the omomyid niche? - adapids are small/medium primates who are arboreal quadrupeds that eat fruit and leaves

Omoyids

Epoch: Eocene
Body size: small
Diet: insectivores
Locomotion: swingers, brachiatting, vcl

Why are the considered "tarsier like"? - in skull composition

Oligocene Platyrrhines

in which epoch do we observe the earliest platyrrhines in s. america? - OLIGOCENE

where do we find extinct platyrrhines-like primates outside of s. america? - THE FAYUM, EGYPT

what other mammals appear in s. america at the same time as platyrrhine primates? - BRANISELLE (earliest platyrrhine)

Eocene Anthropoids: EOSIMIAS

where are they found? - CHINA

epoch: EOCENE

Where is the Fayum geographically?

Egypt

How diverse taxonomically are the Fayum anthropoids?

Aegyptopithecus and other early catarrhines

Locomotion of Aegyptopithecus

arboreal quadruped

What molar type to hominoids have?

5 point

In which epoch is hominoid taxonomic diversity highest?

miocene

During the miocene, where are hominoid found geographically?

africa

When did hominoid diversity decline?

mid-miocene

Describe the locomotor diversity of miocene hominoiods

suspensory, arboreal and terrestrial quadrupeds

Describe the dietary diversity of miocene hominoids

fruits, leaves, insects, seeds, meat

Describe the body size diversity of miocene hominoids

small-large

1) What were africa and asian primate communities like in the miocene?

2) What about today?

1) more apes than monkey species

2) more monkeys than ape species

What are two factors that are hypothesized to explain the loss of hominoid diversity in late miocene?

1) as global cooling restricted forest environments towards the tropic, ape distribution shrank too

2) in more open habitats, apes were unable to compete (old world monkeys)

How do differ from apes?

we are bipedal
small canines (nondimorphic)
non honing canines
big brains
broad dietary niche that includes meat
we acquire and process our food with tools
nondivergent toe
valgus knee
anterior foramen magnum

Morphological correlates of bipedalism

foramen magnum position
spine curvature
pelvis
knee
foot shape/function

Foramen Magnum position

biped - anterior

quadruped - posterior

How does the foramen magnum position influence the location of the spine in relation to the cranium?

if you're a biped your spine will be placed vertically up and horizontal if you're a quadrupedal

Curvature of the spine

Bipeds have THREE
- cervical lordosis
- thoracic kyphosis
- lumbar lordosis

Quadrups have ONE
- thoracic kyphosis

In what direction does a lordotic curve bend?

inward

Without these curves, which way would a biped tend to fall over?

EVERYWHERE - right, left, forward, backward

Why do chimps stand and walk bipedally with a bent hip, bent knee posture?

- no valgus knee
- doesn't have either lordosis curves

Biped pelvis

Sagittally rotated, short and wide

Quadruped pelvis

Coronal, long and tall

Biped maximus

positioned behind the hip, which allows it, along with the hamstrings, to extend to the thigh, pulling it to the rear during walking/running and they provide more force

Quadruped maximus

positioned to the side of the hip and functions to pull the thigh to the side and away from the body

Quadruped glute muscles

extensors

Biped glute muscles

stabilizers

How does changing the shape of the ilium change the function of the gluteal muscles?

alterations to the ilium, repositioned the attachments of several key muscles and changing their mechanical function

In a biped, the gluteal muscles prevent us from falling in which direction relative to the unsupported food?

falling over relative to the unsupported foot

Valgus

presence of bicondylar angle and femur is inward

Valgus vs Straight

valgus (biped)
straight (quadrup)

Big toe

hallux

In line with other toes or divergent

non divergent in bipeds so toes are parallel to each other and the toe can not move

divergent in quadrupeds so the toe is movable (like our thumb)

how does a human "toe off"

start with a heel strike, followed by a toe off

what is a divergent toe used for

grasping and shock absorbers

canine nonhoning complex

(diastema) space between 2 teeth to accommodate large canines (not in humans)

sectorial/honing premolar

lower mandibular premolar that is used to sharpen upper canine

which three teeth comprise the canine honing complex in extant apes?

maxillary canine, mandibular canine, sectorial premolar

pregnancy/birth

267 days

infancy

period up to weaning, all mammals are dependent on their mothers for food until they are weaned

childhood

when weaned, lose dependency on mom for food

juvenility

first eruption of permanent teeth, specifically your first molar

adolescence

starts when the body is capable of reproduction (sexual maturity)

adulthood

starts around 18, until you die

menarche

first menstruation in females

menopause

early senescence of female reproductive organs, no ovulation=no pregnancy

weaning

not depending on your mother for nutrition (when you stop breast feeding)

sexual maturity

when your body is capable of reproduction

puberty

sexual/physical changes such as voices, breast, etc

physical maturity

growth spurt

senescence

aging of an organ system

lactational ammenorhea

can't get pregnant when nursing

interbirth interval

period of time between births

why would the earliest hominin have looked very ape like

there weren't as many derived traits, all we had were apes

allopatric speciation

populations become more isolated from each other

what role does gene flow play in speciation?

lack of gene flow leads to divergence, accumulation of reproductive isolation mechanism, and eventually speciation

what evolutionary scenario was envisioned by early thinkers that linked brain size, canine size, diet, locomotion, and tool use?

human evolution

which feature was expected to appear first and drive the evolution of the remaining features?

big brains

Kenya

Ethiopia

South Africa

Tanzania

Chad

African Rift Valley

what is the african rift valley? - crack in the earths crust from Lebanon to Mozambique, divides Kenya in 2 sections - rich in fossils that allow study of human evolution

Hadar

Laetoli

Afar Triangle

Lake Turkana

Sahelanthropus tchadensis

area of discovery: southern chad
age: 7 MYA
discoverer(s): Michael Brunet
Name meaning: Sahara human from Chad
why it may be hominin: foramen magnum may be forwardly placed, small unsharp canines
why it may not be hominin: small cranial capacity, large brow ridge prominence, post canine teeth enamel, thich supraorbital torus

Orrorin tugenensis

area of discovery: Tugen Hills, Kenya
age: 6 MYA
discoverer(s): Martin Pickford and Brigette Senut
name meaning: first human
why it may be hominin: shape of femur head, canine not large and not honed, post canine are argued to be thickly enameled
why it may not be hominin: no distal end of femur, limited sample size

Ardipithecus ramidus

area of discovery: Afar triangle of Ethiopia
age: 4.4 MYA
discoverer: tim white
name meaning: ground ape
why it may be hominin: anterior foramen magnum, less facial prognathism, no knuckle walking, bipedal pelvis
why it may not be hominin: grasping feet with divergent hallux

Australopithecus Afarensis (pliocene hominins)

area of discovery: Hadar, Ethiopia, Laotoli
discoverer(s): Don Johanson, Mary Leakey
age: 2.9-3.7 MYA
chimp like cranial morphology
small brain
very high sexual dismorphism
reduced nonhoning canines