Secondarily aquatic Tetrapods Flashcards
1
Q
Cetaceans - “A poster child for macroevolution”
A
- great fossil record
- molecular divergence dates
- lots of derived traits with known molecular basis
- convergence with other taxa
- increasing number of genome sequences
- semi-aquatic hippos represent intermediate forms
2
Q
Other secondarily aquatic tetrapods
A
- sea turtles
- crocodylomorphs
- snakes
- marine iguana
3
Q
“The aquatic problem”
A
1) Propulsion – can’t walk in water
2) 2D vs 3D (rolling)
3) (inertial/viscuous) Drag – water is denser and more viscous than air, increases drag
4) Breathing – still need to come to surface for air
5) Bouyancy – breathing air makes animals float (pachyotosis/osteosclerosis - denser bones, gastroliths)
6) Water & salt
7) Heat conductivity
8) Senses – water affects light and sound differently than air
4
Q
Convergent evolution
A
the process by which unrelated species evolve similar traits, often due to similar lifestyles
