BIOL 4141 Chapter : Cetacea Mammology 2014
Document Summary
Cetacea: fully adapted to aquatic life, feed at the middle or top of marine food web, ability to echolocate, considerable intelligence, complex social behaviors. Figure 19-1: phylogeny illustrating the evolutionary transition from the quadrupedal pakicetusto, the semiaquatic. Paleontology: first whales from eocene (~50 mya) of tethys sea. Some later forms (mysticeti) had both teeth and baleen: limited bulk filter feeding possible. Middle miocene mysticetes lost teeth: elongate rostrums to support more baleen, bulk filter feeding. Paleontology: transition to filter feeding corresponds to opening of circum-antarctic currents. Figure 19-2: skull of a primitive cetacean (dorudon), a fossil archaeocete from the eocene. Paleontology: odontocetes (toothed whales) sister to mysticetes, highly telescoped skulls, homodont and monophyodont dentition, evolution of echolocation. Morphology: body fusiform, nearly hairless, thick layer of subcutaneous blubber, teats enclosed within slits next to urogenital opening, testes remain abdominal, vertebrae with high neural spines. Left forelimb of the bottlenose dolphin (tursiops truncatus, delphinidae) Cervical vertebrae of a dolphin (delphinus delphis, delphinidae).
