Evolution (exam 2)

Question 1

Geological time periods

Answer 1

Cambrian, Ordovician, Silurian, Devonian,
Carboniferous, Permian, Triassic, Jurassic, Cretaceous

camels, often, sit, down, carefully, perhaps, their, joints, creek

Question 2

Major fish groups

Answer 2

Ostracoderms, Placoderms, Acanthodians, Chondrichthyans/Chondrichthyes,
Sarcopterygians/Sarcopterygii, Eusthenopteron, tetrapodamorphs, Actinopterygians, Teleosts.

Question 3

Ostracoderms.

Answer 3

Ordovician time, extinct in Devonian time
No jaws
First vertebrates cartilaginous internal skeleton
Bony exoskeleton (bony armor)
bottom dwellers

Question 4

Placoderms.

Answer 4

Silurian time → Carboniferous time
First jawed fish (holostylic, no teeth)
Holostylic = clamping motion, limits way you can feed
Heavily armours, mainly in head
Paired fins (had more mobility)
Body type: Was dorso-ventrally compressed

Question 5

Acanthodians

Answer 5

Silurian time → Permian time
Loss of bony exoskeleton → Cartilaginous skeleton —> become more moveable
Jaws improve ventilation of gills
Rows of ventral paired “fins”
Body time: Fusiform body

Question 6

Chondrichthyans/Chondrichthyes

Answer 6

Cartilagionoius fishes
Silurian time → persists today
Few freshwater forms
Most were apex predators
Bony skeleton
Replaceable teeth, derived from scales
Hyostylic jaws

Question 7

Sarcopterygians/Sarcopterygii

Answer 7

Lobe-finned fishes
Appeared in Silurian, persist today
Fin lobes contain complex bone structure
Holostylic jaw suspension
Dominant predators of Devonian, only 8 species today
3 groups:
1) Coelacanths,
2) Lungfishes,
3) tetrapodamorphs

Question 8

tetrapodamorphs

Answer 8

Extinct in Permian
Robust linkages between skeleton and fins: evolutionary precursors to limbs of land vertebrates
One line gave rise to tetrapods

Question 9

Actinopterygians

Answer 9

rayed fins
Appeared in Devonian, persist today
2nd major group (Subclass) of bony fishes
>95% bony fishes today are ray‐fins

Question 10

Teleosts

Answer 10

Probably appeared in Triassic (~250 MYA)
Diversified explosively * Probably arose in freshwater
today 1% of habitat, 40% of species
Today: ½ of all vertebrate species, 95% of fish species
Talkii, went from ocean to land
–> had hands/wrist which was missing link