Lecture 8 - Oligocene & Miocene Flashcards
Miocene
early Miocene faunal trend
faunal exhange between Africa and Asia
miocene
climate optimum
17-15 Ma
- widespread forests
- apes diversify and leave Africa
Miocene
result of Africa island isolation
- endemic fauna = not found elsewhere
- very diverse fauna, more than today
- Afrotheria - group of animals that evolved in Africa when it was isolated from the world (elephants, elephant shrews, sea cows, hyraxes)
miocene
what happened 17.3 - 16.4 Ma
- land bridge that connected Africa to Eurasia
- asymmetric exchange of animals –> more came into Africa than left
- elephants particularly successful - spread all over the world
grasslands in NA
when, how, results
latter half of Miocene, trend of aridification (drying out)
- resulted in climate driven evolution –> coev of horses and expanding grasslands
grasslands in NA
early horse ancestor traits
- lived in forest/tropical settings
- ate soft/pulpy vegetation
- did not have cursorial adaptations (to run fast)
grasslands in NA
cursorial adaptations
to run extremely fast
- when living in open settings, visile to predators so prey has developed cursorial adaptations
grasslands in NA
horse adaptation to grasslands
long legs
one toe
higher teeth - hypsodonty
grasslands in NA
what is hyposdonty
- linked to open habitat grazing
- many groups have developed –> suids, rhinos, equids, marsupials, sloths, rodents
- suited for extremely abrasive diets that can be worn down
grasslands in NA
structure of hypsodontic tooth
dentine & cementum - fill in btwn enamel but are softed
- chop grass pieces btwn enamel
- enamel wears, but still able to use them
grasslands in NA - hypsodonty
why do grazers wear teeth
silica phytolithis
- grasses contain cell structures made of silica (biogenic opal) called phytoliths, internal grit
- more abundant in grasses than in leaves
dust
- covers grass, external grit
rise of grasslands in Africa
begins around 10 Ma and progresses towards end of Miocene
- important implications for human resources –> little shelter or food resources
miocene apes
primate adaptations
- arboreal & terrestrial quadrapedal
- clinging and leaping
- suspensory locomotion
miocene apes
proconsul/ekembo
Kenya, Uganda - 25-23 Ma
- above branched quadraped, monkey-like in general lifestyles
- no tail & dental anatomy points towards ape relatives, but acted like apes
miocene apes
dryopithecus
Europe - middle to late Miocene
- more suspensory adaptation
miocene apes
Sivapithecus
India & Pakistan - 12-7 Ma
- cranially looks like orangutan
- doesn’t show postcranial specializations for suspension
living apes - Hominoidea
current living apes and where
orangutans - indonesia
gorillas - tropical africa
chimps & bonobos - tropical africa
gibbons & siamangs - tropical SE asia
humans
living apes - Hominoidea
where & when do earliest apes occur
Africa - 25 Ma: Proconsul
faunal exchange between Africa & Eurasia
- hundreds of sites in Eurasia that preserves apes from Miocene
living apes - Hominoidea
comparison to modern apes
- cranial adaptations modern ape like
- postcranial adaptations not ape-like
- extremely suspensory locomotion not until end of Miocene
- hyperdiverse, all over the globe
living apes - Hominoidea
monkeys/cercopithecoids, now vs Miocene
now: hyperdiverse, all over globe
miocene - opposite of now, only couple of early monkeys
monkeys appear in late Oligocene/ early Miocene but don’y diversify until Pliocene
living apes - Hominoidea
apes vs monkey diversification
apes are adapted to moist, tropical environments
monkeys are much more successful in open, dry environments
- apes hold onto the same places today (less diverse)
class paper
koch 1998
isotopic analysis (using OCN) of teeth and bones reflects various aspects of an animal’s diet, water intake, and habitat
