ANAT2009 - Comparative Primate Anatomy

three adaptive trends of primates

arboreal, free mobility of digits, primitive structure

adaptations to living in trees

nails for grasping, large flat sensitive tactile pad with flat nail

free mobility of digits

long limbs, prehensile digits, good joint mobility, opposability of fingers and toes

forelimbs used for

grasping, manipulating, feeding

locomotion is

hindlimb driven

primitive structure

retention of clavicle, rotation of shoulder, wrist, radius, ulna allow for pronation

eye sockets bounded by

postorbital bar

visual predation theory

matt cartmill 1972 where primates developed adaptations to tree life to forage for food using their hands for consumption

reduction of sense of smell

use touch to examine, reduction of snout size

parental care invested in offspring

large amounts invested in small number of offspring

increased primate brain size

linked to information processing capabilities

large brains evolve due to

selection of cognitive abilities to exploit the environment for fruit, large spatial memory, good colour vision

tree shrew

primate but does not have all characteristics with claws and projecting snouts

prosimian - lemur

found in madagascar only, nails, long snout

prosimian - lorus

found in Africa and parts of Asia, nocturnal, nails, long snout

tarsier

nocturnal, large ears, eye sockets have posterior bony wall, smaller snout, stereoscopic vision

spider monkey

arboreal and quadrupedal, broad flat noses, retain 3 premolars

baboon

arboreal and quadrupedal, live on ground primarily, two premolars

apes - gibbon and siamang hylobates

smaller than other apes, long limbs, no tail, best brachiators

hylobates

greek for ones who haunts the woods

brachiation

arm swinging, form of arboreal locomotion where primates swing from tree limb to tree limb with only arms

great apes - orangutan

malay or indonesian, long limbs, no tail, fist walker, solitary

pongo

fictional monster

great ape - common chimpanzee

pan troglodytes, Africa only, arboreal and terrestrial

pan

god of the forest

troglodytes

cave dwelling

ape - pygmy chimpanzee

pan paniscus, bonobo, arboreal and terrestrial, larger breasts

paniscus

small pan

great ape - gorilla

largest of great apes, knuckle walker, marked sex differences

gorilla sex differences

silver hair along his back and crest on top of skull

binomial nomenclature

latin system founded by Swedish botanist Carl Linneaus

phylogenetic relationships are inferred on basis of

patterns of shared similarities

similarities

morphological, behavioural, physiological, chromosomal, biochemical

evolutionary tree criterion

capacity to absorb new fossil finds

plesiadapids

late cretaceous period, 65 mya in North America and North Africa that are mouse sized, fruit eaters, quadruped

proconsul

miocene about 20 mya, quadrupeds with suspensory ability, no tail, an opposable thumb and increased brain size

Australopithecus

southern ape

hominoids

all humans and all apes (complete tree and gibbons)

hominids

all modern and extinct great apes and humans and their ancestors (complete tree)

hominins

all humans and their ancestors

hominin adaptations

locomotion, jaws and teeth, reduced jaws (orthognathic) and increased intelligence

hominin locomotion

bipedalism to free the hands, spot predators and prey, easier to pick fruits from branches, enable humans to appear large and intimidating, cover wide open landscapes efficiently and quickly

hominin jaws and teeth

parabolic dental arcade, loss of diasteme due to smaller canines, small incisors, large posterior teeth and efficient grinding

diastema

space between two teeth to make space for projecting teeth above or below

hominin reduced jaws (orthognathic) rather than projecting jaws (prognathic)

reduction in size of teeth

hominin increased intelligence

changes in brain size, changes in structure of brain

hominins have in common

reduced canines, bipedal adaptations, small brains

Sahelanthropus

7 mya, Chad, Central Africa, brain volume 320-380 cc, foramen magnum further forward than in apes or any other primates except humans, human-like canines, small and more incisor-like canines

Sahel

area of Africa near the southern Sahara where fossils were found

Anthropus

Greek word meaning man

Orrorin

means original man in Kenyan language, 6 myo, Kenya, femur has long neck, only a few long bones, part of mandible and teeth found, long, curved finger bones and ape-like canine and premolar teeth

Ardipithecus

Ethiopia in 1994, bipedal, grasping big toe so quadrupedal in trees, hands adapted for arboreal life, reduced canine, small brain, 4-6 myo

Ardipithecus means

ground ape

Ardipithecus ramidus

4.4 my

Ardipithecus kadabba

5.6 my

Australopithecus afarensis “Lucy”

from afar region in Ethiopia, 4-2.5 my, apelike features in forearm and small brain, East Africa, small canines, enlarged molars, pelvis and vertebral column for upright posture

Laetoli footprints

two early humans walked through wet volcanic ash in Laetoli, Tanzania 3.5 mya likely made by A. afarensis whose fossils were found in the same sediment layer

Australopithecus africanus

described by Raymond Dart 1924, fossil of Taung child, 3-2.5 mya, discovery challenged human origins in Asia to Africa

Africanus means

from southern Africa

Taung child

400-500 cc, bipedal, no diastema, small brain, challenged the idea that brain expansion came first followed by upright stance and bipedalism

Paranthropus robustus

Southern Africa, great enlargement of face, jaws, and teeth, moderate sexual dimorphism, 2-1 my

Paranthropus means

near to human

Paranthropus boisei

East Africa, described by Richard Leakey, marked sexual dimorphism, great enlargement of face, jaws and teeth, 2.6-1.2 my

Boisei means

named after a benefactor

Homo habilis

handy, 2.4 my, found only in Africa, 550-770 cc, molars and premolars are small and narrow, less projecting face, long arms, tool maker

Homo erectus

erect posture, 1.8 my, Ethiopia, large brain 850-1200 cc, teeth smaller than H.habilis, prominent brow ridges, made tools

KNMER 15000 Turkana Boy

most complete hominoid specimen found, less than 12 years old, 168cm tall

Homo floresiensis

1m tall, hobbit, bipedal, long arms, primitive teeth, small brain 380 cc, 100,000 to 60,000 years, long low cranial vault, prominent canine pillars, large face, small braincase, thought to be dwarfed form of H.erectus, Indonesia

endocranial volume

good indicator of brain size

limb proportions important for

reconstructing locomotion and clarifying phylogenetic relationships

LB1

pathological H.sapiens with microcephaly (small brain) with normal size face and small stature, cretin

cretins prenatal development disrupted by

lack of iodine and hypothyroidism

Homo neanderthalensis

Europe and western Africa, overlapped in time with H,sapiens, evolved after H.erectus left Africa, large brain 1200-1400 cc, teeth smaller except for incisors, brow ridge larger than H.sapiens, very large nose, mid face projection, heavily built as adapted for cold, made tools

examples of H.neanderthalensis

France - La Chapella, Germany - Neander Valley, Iran - Shanidar

Homo sapiens

200,000 years, found everywhere - North Africa, South Africa, Europe, Palestine, large brain 1100-1800 cc, moderate to small brow ridges, less prognathic face, chin, smaller teeth, skeleton adapted for warm environment, complex culture

aDNA study

2023 study using ancient DNA looked at modern African genomes that found that origin is in Africa using modern DNA to work backwards using computer modelling

aDNA study results

species arose from two African populations that interacted and interbred with each other

out of africa theory

africans moved out of Africa to other parts of the world, DNA supports this theory

multiregional theory

H.erectus moved out and interacted with different species

earliest dates for human occupation of australia

50,000 years from Malakunaja rock shelter, Arnhem land, Northern territory

oldest australian human fossils from

Lake Mugo in far western NSW 45,000 years

first H.sapiens reached

Asia 70,000 years ago

pectoral girdle

clavicle and scapula

function of upper limb

manipulation

mobility of upper limb dependent on

pectoral girdle

bony connection of pectoral girdle to axial skeleton

sternoclavicular joint

humerus articulates with the scapula

glenohumeral joint

upper limbs used in humans

locomotion, climbing, manipulation, throwing, balance, support

long clavicles and dorsally placed scapulae found only in

primates

medial (sternal) end articulates with

sternum, rounded

lateral (acromial) end articulates with

acromion of scapula, flattened

clavicle anterolateral part

has the deltoid tuberosity for attachment of deltoid

clavicle posterolateral part

has roughed area for attachment of trapezius

clavicle anteromedial surface

anchors part of pectoralis major

costoclavicular impression

for ligament for 1st rib

trapezoid line

for trapezoid ligament from coracoid process

conoid tubercle

for conoid ligament from coracoid process

sternoclavicular joint movements

clavicular elevation/depression and clavicular protraction/retracting

scapula angles

superior, inferior, lateral (glenoid fossa)