evolution

Question 1

roles of equids in society

Answer 1

food source, spiritual symbols, warfare, hunting, work, transport, sport, companions

Question 2

horse taxonomy: class

Answer 2

mammalia

Question 3

family

Answer 3

equidae

Question 4

genus

Answer 4

equus

Question 5

domestic breeds are

Answer 5

Equus caballus

Question 6

equus asinus

Answer 6

african wild ass

Question 7

equss burchelli

Answer 7

east african zebra

Question 8

equus grevyl

Answer 8

grevy’s zebra of east africa

Question 9

equus zebra

Answer 9

south african zebra

Question 10

equus kiang

Answer 10

asian ass

Question 11

equus hemionus

Answer 11

middle eastern/asian ass

Question 12

equus przewalski

Answer 12

last truly wild horse

-from Mongolia

Question 13

last common ancestor of domestic and przewalski

Answer 13

4. 5 million years ago

- no genomic evidence of prze mixing with domestic, so they retain their genetic diversity

Question 14

accurate picture of horse evolution

Answer 14

• not a straight line
• different traits evolved at different rates; not always evolving together and occasionally reversed
• development was not always gradual either
• ancestors did co-exist

Question 15

adaptations: digits

Answer 15

from 4 to 1 central digit, adapted for running on hard ground, receiving impact of their heavier bodies, and for kicking predators

Question 16

adaptations: long, crowned, hard teeth

Answer 16

-adapted for grazing on fibrous/tougher vegetation found on open, dry plains

Question 17

adaptations: fossae

Answer 17

a depression or hollow point of skull, allowing for greater jaw muscle strength

Question 18

adaptations: brain

Answer 18

larger cerebral hemispheres

Question 19

hyracotherium (“eohippus”)

Answer 19

• 54-34 mya
• north american small forest animal
• looked like “a dog”
• ate fruit and soft foliage
• 4 digints in front, 3 on back (1-2 vestigal digits)

Question 20

epihippus

Answer 20

• 47 mya
• teeth change to allow for tougher food intake
• some premolars more like molars for grinding

Question 21

mesohippus and miohippus

Answer 21

• medium sized browsers/grazers
• late eocene, oligocene: climate of NA gets drier, grasses evolving and forests shrinking
• larger, taller, less doglike, longer faces, 3 digits, horse brain develops
• 6 grinding teeth

Question 22

Plains horses: grinders

Answer 22

-crests on teeth enlarged and connected together in series of ridges for grinding
-hypsodont teeth: teeth keep growing and must be worn down through use
cement layer on teeth made them harder

Question 23

plains horses: runners

Answer 23

• increase body size, leg length
• 1 digit in some
• muscles and legs specialized for forward and back strides
• standing on tips of digits with springy ligaments on central phalanx

Question 24

parahippus and merychippus

Answer 24

17 mya

• 3 digits
• radius and ulna FUSED so leg rotation is eliminated
• fibula greatly reduced
• eyes moved further back to accomodate large tooth roots
• larger brain

Question 25

merychippene radiation

Answer 25

miocene - 19 new grazing horse species in three major groups: 1. hipparions 2. protohippines 3. merychippines (3 and 1 digits horses)

Question 26

1 digit horses

Answer 26

-late miocene, pliocene, and pleistocene | pliahippus, hipparion, and dinohippus

Question 27

pilohippus

Answer 27

similar to modern horse

Question 28

hipparion:

Answer 28

3 digits, grazers and browsers, spread from new to old world

Question 29

dinohippus

Answer 29

common in NA, probably gave rise to modern Equus - 1 digit with side ligament to prevent twisting - long nose - high crowns, straight grazing teeth with crests lined with cement

Question 30

old equus

Answer 30

common ancestor 4.5 mya - 12 species, coexisting with hipparions, protohippines, and astohippus - pony sized, 1 digit

Question 31

Splint bones

Answer 31

- metacarpals 2 and 4 are usually vestigial "splint bones" around large central 3rd digit - rarely, modern equus can be born with small but fully formed side toes

Question 32

spread of equus

Answer 32

- major glaciations of late piocene (2.6 mya) allows species to cross to - africa, creating zebras - asia, mideast, and N Africa as desert-adapted onagers and asses - asia, mideast, and europe as the true horse E. Caballus - south america - other species died out, with Equus surviving

Question 33

extinction 10,000 years ago

Answer 33

removed equus from Americas | -no definitive reason, could have been due to changes in environment, disease, or overhunting by humans

Question 34

other existing relatives:

Answer 34

rhinoceroses and tapirs