module 3: human lineage

cenozoic era temperatures

• overall cooling trend

• fluctuations at beginnings and ends of epochs and major evolutionary events

cause of cenozoic era’s changing temperatures

plate tectonics affect ocean currents which in turn affects the amount of heat

order of cenozoic era epochs

1. paleocene

2. eocene

3. oligocene

4. miocene

5. pliocene

6. pleistocene

7. holocene

epochs in tertiary period

• paleocene

• eocene

• oligocene

• miocene

• pliocene

epochs in quaternary period

• pleistocene

• holocene

paleocene starting event

dinosaurs just went extinct

paleocene habitat change

• angiosperms had just had an adaptive radiation

  • became dominant tree species

• shift from gymnosperm forest to angiosperm forest

gymnosperms

non-flowering trees whose pollen spreads by wind

angiosperms

flowering trees whose nectar attracts animals

when did angiosperms have an adaptive radiation

paleocene epoch, 65 million years ago

angiosperm adaptive radiation

• animals inadvertently carry angiosperm pollen to other plants

• evolved new, large fruit types

  • animals ate these fruit and inadvertently spread its seeds

• became dominant tree species, replacing gymnosperms

angiosperm adaptive radiation effect on early primates

• new, abundant food available— fruits and insects

• allowed for adaptation to support this new diet (binocular vision, grasping hands/feet)

gymnosperm forest

pre-angiosperm forests

gymnosperm forest climate

hot

gymnosperm forest space

open

gymnosperm forest complexity

not particularly complex

gymnosperm forest dominant animals

reptiles

angiosperm forest climate

cooler

angiosperm forest space

closed

angiosperm forest complexity

• lush, many layers

• many niches

angiosperm forest dominant animals

mammals and birds

end of paleocene

primate-like creatures called plesiadapiforms

plesiadapiforms epoch

paleocene

plesiadapiforms characteristics

• primate-like creatures

  • molar shape

  • grasping hands

• also had non-primate traits

  • long snout

  • eyes on side of head

  • claws, not nails

  • no postorbital bar

plesiadapiforms diet

insectivorous and frugivorous

plesiadapiforms relation to primates

a sister group of primates, NOT classified as euprimates (true primates)

living mammals that are most closely related to primates

flying lemurs

eocene event

adaptive radiation of primates

climate at the start of eocene

drastically rising temperatures

result of the start of the eocene’s climate

• many terrestrial mammals went extinct

• numerous modern mammalian orders emerged

eocene environmental factors

northern latitudes had tropical climates, causing rainforests

result of eocene’s environmental factors

• allowed for primate migration— primates like tropics

• adaptive radiation of primate species

eocene primates postorbital bar or closure?

postorbital bar

• helps anchor the eyes

eocene primates snouts

shorter than other mammals

• less reliance on sense of smell

eocene primates eyes

forward-facing

• depth perception and precision

eocene primates nails or claws?

nails

eocene primates opposable thumbs and toes?

yes

two major groups of eocene primates

omomyiformes and adapiformes

omomyiformes primate resemblance

tarsiers

adapiformes primate resemblance

lemurs

omomyiformes epoch

eocene

omomyiformes diet

insectivorous

omomyiformes locomotion

leaping

omomyiformes nocturnal or diurnal?

nocturnal

adapiformes diet

folivorous

adapiformes locomotion

arboreal quadrupeds with some leaping

adapiformes nocturnal or diurnal?

diurnal

eosimiidae epoch

eocene

eosimiidae size

tiny

eosimiidae primate or no?

yes

primate group that is the likely ancestor of all haplorrhines

eosimiidae

end of eocene

lots of primate diversity due to expansion of tropical climates

oligocene climate

• surface sea water much cooler

• antarctic ice cap developed

• northern-most tropical forests disappeared

epoch in which earliest unambiguous haplorrhines were found

oligocene

area in which earliest unambiguous haplorrhines were found

the fayum, egypt

haplorrhine primates in the fayum postorbital __?

closure

haplorrhine primates in the fayum mandible

mandibular fusion

haplorrhine primates in the fayum snout

reduction compared to strepsirrhines

rafting hypothesis

primates and rodents drifted across oceans from African to South America on natural rafts of vegetation and debris launched during storms

rafting hypothesis likeliness

• very likely

• rafting from Africa to South America is supported by ocean currents at the time

all living new world monkeys are descendants of which event?

rafting

epoch in which the earliest south american primates lived

oligocene

end of oligocene/start of miocene climate

• warming temperatures

• reemergence of tropical forests/northern tropical climates

  • suggests another primate radiation

miocene huge primate radiation of which group?

apes

preconsul species primate group

ape

preconsul species location

europe

preconsul species dentition

y5 molars

preconsul species brain

larger than normal

preconsul species snouts

drastically reduced

preconsul species shoulder

flexible

oreopithecus epoch

late miocene

oreopithecus location

tuscany, italy (europe)

oreopithecus evidence for potential bipedality

• widely displaced big toe

• inner ear bony labyrinth

most recent living relatives of humans

chimps and bonobos

mid/late miocene ape diversity

decreasing everywhere

african ape fossils between 15-8 million years ago (mid/late miocene)

• huge gap in fossil record

• very few, poorly preserved fossils

• ape diversity decreasing everywhere

pliocene

epoch in which earliest hominins are found

pliocene primate groups

ardi and australopithecus

pleistocene primate group

paranthropus, australopithecus, homo

holocene primate group

homo— only survivor

foramen magnum

the hole in the bottom of the skull through which the spinal core enters

bipedality

walking on two legs

lumbar lordosis

inward curvature at the base/lower spine

sacrum

triangular shaped bone in pelvis located at the base of the spine that continues the lumbar curve

center of gravity

the specific point where the body’s weight is balanced in all directions

center of gravity is affected by…

lordosis

quadrupedal

walking on four limbs

iliac blades

wings of the pelvis

valgus knee

knees angle inward and are brought more under the hips

convergent toe

big toe is aligned with/parallel to the other toes

divergent toe

big toe is separated from the other toes

use for divergent toe

grasping

hominid

humans and all great apes

hominin

group of bipedal hominids after the split of the last common ancestor of chimps, bonobos, and humans

how many of the living hominids are habitually bipedal?

one

honing premolars

premolar sharpens the upper canine

intermembral index

forelimb length/hindlimb length x 100

position of foramen magnum in habitual bipeds

• positioned directly under the skull

• head is balanced on vertebral column

  • makes a right angle

shape of ribcage in habitual bipeds

• barrel-shaped

• advantageous for maintaining balance

  • easier arm-swinging

curvature of the spine in habitual bipeds

lordosis curve brings the hips forward