History of Fishes Flashcards
1
Q
Chordata characteristics
A
- dorsal nerve cord
- notochord
- pharyngeal gill slits
- post anal tail
2
Q
urochordata
A
tunicates
3
Q
cephalochordata
A
lancelets
4
Q
craniata
A
hagfish & vertebrates
5
Q
ostracoderms
A
- early vertebrates
- dermal armor
- marine then freshwater fossils
- jawless filter feeders
6
Q
Vertebrata
A
- ectodermal & mesodermal layers of skin
- respiration via gills or lungs
- skeleton
7
Q
Agnatha - jawless
A
- problematic group
- lampreys & hagfish extant members
8
Q
where did jaws derived from?
A
gill arches
9
Q
Gnathostomata
A
- jawed vertebrates
- monophyletic
- paired limbs usually present
- dentine based teeth
- no intermediate forms known
10
Q
Placoderms
A
- sister to all Gnathostomes
- heterocercal tail
- bony plates instead of teeth
11
Q
Chondrichthyes
A
- Devonian origin
- early fossils are teeth, scales, and spines
- cartilaginous skeleton
- 4-7 gill opening
- placoid scales
12
Q
2 types of Chondrichthyes
A
- elasmobranches
- homocephalans
13
Q
Acanthodians
A
- spiny sharks
- oldest known advanced jawed fishes
- many spines
- cartilaginous skeleton
14
Q
Acanthodians cartilaginous skeleton
A
- operculum
- 3 otoliths
- brachiostegal rays
- small head
- large eyes
15
Q
Osteichthyes
A
- sarcopterygians, actinopterygians
- bony fish
- some to complete ossification
- scales
