Major Events In Vertebrate History

Question 1

When did vertebrates evolve?

Answer 1

~500,000,000 years ago

Question 2

What are conodonts?

Answer 2

Pre-vertebrates
• Eyes, gills, mineralised skeletal elements
• First known 485mya but must have been earlier

Question 3

What result did whole genome duplications have?

Answer 3

Extra copies that evolution can act on

-> Hox genes

Question 4

Describe a craniate

Answer 4

• True neural crest and placodes
• Skull
• Paired eyes
• Ears
• Nose

Question 5

What living pronto-vertebrates exist?

Answer 5

Hagfish and lampreys

Question 6

Describe jawed-vertebrates

Answer 6

• Jaws
• Paired pectoral and pelvic fins
• True teeth
• Mineralised skeleton
• Complete vertebrae

Question 7

What three parts is the skill made up of?

Answer 7

1. Dermal bones
2. Cartilage bones surrounding brain and sense organs
3. Viscerocranium- develops from original gill skeleton

Question 8

When was the evolution of jaws and paired fins?

Answer 8

430mya

Question 9

What happened to ancestral craniate gills?

Answer 9

• Lost one/two anterior pairs of gills
• First of remaining-> mandibular arch (jaws)
• Second-> hyoid arch (hyoid apparatus/stapes)

Question 10

Describe lobe fins

Answer 10

Muscular fins with central axis, accessory air breathing organs

Question 11

What fish today have lobe fins?

Answer 11

Lungfish and coelacanths

Question 12

Describe a tetrapod

Answer 12

Limbs with digits

Transition to land

Question 13

How many digits do frogs have?

Answer 13

4

Question 14

How do digits differ from fin rays?

Answer 14

Digits are endochondral bone, fin rays are dermal bone

Question 15

Describe a land tetrapod

Answer 15

• Jointed fore and hind limbs
• Middle ear
• Lung breathing
• Waterproof Skin
• Water conserving kidneys

Question 16

Describe an amniote

Answer 16

• Amniote egg with chorion
• Amnion
• Allantois

Only evolved once- all descendants are amniotes

Question 17

How do mammals differ from reptiles?

Answer 17

• Diphyodont dentition- two generations of teeth
• Heterodont dentition- different teeth, different function
• Bony secondary palate- separate air and food
• Single lower jaw bone
• Dentary-squamosal jaw joint (reptiles have only quadrate-articular=mammal eat)
• Three ear ossicles- stapes, incus, malleus (reptiles one)
• Larger brain and skill vault, fur and mammary glands, upright stance

Question 18

What caused the first major extinction?

Answer 18

Massive lava flows in Siberia raised CO2 and other gases-> global warming and acid rain

Question 19

What caused the second major extinction?

Answer 19

Massive asteroid (10km) hit Earth in Yucatan Peninsula of Mexico

Question 20

When did mammals enter the air?

Answer 20

53mya

Question 21

When did mammals re enter the water?

Answer 21

50mya

Question 22

When were the first recognisable primates?

Answer 22

55mya

Question 23

When did chordates evolve?

Answer 23

540mya

Question 24

When did craniates evolve?

Answer 24

530mya

Question 25

When did jawed vertebrates evolve?

Answer 25

435mya

Question 26

When did lobe fins evolve?

Answer 26

420mya

Question 27

When did tetrapods evolve?

Answer 27

390mya

Question 28

When did frogs and salamanders diverge?

Answer 28

From tetrapods- 390mya

Question 29

When did amniotes evolve?

Answer 29

320mya

Question 30

When did reptile and bird lineages diverge?

Answer 30

From amniotes- 320mya

Question 31

When was the first major extinction?

Answer 31

250mya

Question 32

When was the evolution of mammalian characters?

Answer 32

320-205mya

Question 33

When did true mammals evolve?

Answer 33

205mya

Question 34

When was the second major extinction?

Answer 34

66mya

Question 35

From when did mammals start to diversify?

Answer 35

64mya