Tetrapods Flashcards
1
Q
Tetrapods
A
Amphibians + Amniotes
2
Q
General Characteristics
A
- Evolved from 4-limbed ancestors
- All vertebrates that aren’t fish
3
Q
Differences between aquatic and terrestrial environments
A
- Oxygen content (air»_space; water)
- Fluid density (air < water)
- T° regulation
- Habitat diversity
4
Q
Origin of tetrapods
A
Paired fins of lobe-finned fish are homologous to amphibian fins
5
Q
Evolution of tetrapod limbs
Eusthenopteron
A
- Devonian lobe-finned fish
- Upper arm bone (humerus)
- 2 forearm bones (radius/ulna)
- Wrist bones
- Pushed itself along bottom with fins
- Couldn’t walk upright
6
Q
Evolution of tetrapod limbs
Acanthostega
A
- Early tetrapod
- Fore- & hindlimbs
- 8 toes
- Too weak to walk on land
- Likely exclusively aquatic
7
Q
Evolution of tetrapod limbs
Ichthyostega
A
- Could walk on land
- Shoulder & hip girdle
- Well-developed muscles
- Stronger backbone
- 7 toes
8
Q
Evolution of tetrapod limbs
Limnoscelis
A
- Terrestrial
- 5 digits on fore - & hindlimbs
- Became tetrapod standard
