Lec 7 Bats & Whales

Question 1

2 main skeletal characters showing whales are artiodactyls

Answer 1

ectotympanic with involucrum and sigmoid process
double-pulleyed astragalus

Question 2

2 Clades of modern whales

Answer 2

Odontocetes - have echolocation
Mysticetes - baleen

Question 3

Traits showing whales are fully aquatic

Answer 3

fusiform body
dorsal fin
reduction and modification of limbs
horizontal tailfin for propulsion
posterior migration of external nares

Question 4

Limbs of whales

Answer 4

forelimbs:
- paddle-like
- shorten, flat humerus, radius, ulna
- digits elongated and increased

hindlimbs:
- reduced
- innominata don’t articulate with sacral vertebrae

Question 5

Flukes of whales

Answer 5

swing dorsally and ventrally for propulsion -> non recovery stroke
fluke: stabilization

Question 6

Skull of whales

Answer 6

telescoping:
nares extend far back on skull
anterior bone extend posteriorly to overlap parietal

Odontocetes: asymmetric skull for directional hearing
Mysticetes: symmetric

Question 7

How do whales hear?

Answer 7

No external auditory meatus

thin wall of dentary receives waves and transmits via fat pad/ enlarged mandibular foramen to tympanic plate

petrosal unattached to skull to avoid bone conduction