Lecture 24_handout

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Cetacea
●
●
●
Suborder Mysticeti
–
Baleen Whales
–
4 families, 6 genera, 11 species
Suborder Odontoceti
–
Toothed Whales
–
9 families, 34 genera, 68 species
Suborder †Archaeoceti
–
extinct (ancient) whales
Mysticetes vs. Odontocetes
• Baleen whales
• Large body size
• Feed on plankton and
other small marine
organisms
• No echolocation (but
have sound production
for communication)
• Toothed whales
• Small, mobile, agile
• Actively hunt fish and
larger prey
• Echolocation
Odontocetes
Mysticetes
River Dolphins
Cassens, Insa et al. (2000) Proc. Natl. Acad. Sci. USA 97, 11343-11347
Evolution of the Whale Skull
• Heterodont
Homodont or
Edentulous
• Telescoping of
premax & max
Posterior migration of external nares
Odontocete jaws
Dental adaptations
Dental adaptations
Dental adaptations
Whale migration
Echolocation in Odontocetes
Echolocation in Odontocetes
Baleen
Mysticete feeding
Skimming
•Right whales
•Grey wales
Gulping
•Rorquals
Frontomandibular stay
Bubble-net feeding
Bottom feeding
Myoglobin concentration
Oxygen stores
Counter-current heat exchange
G. G. Simpson (1945), Principles of classification and
a classification of mammals.
“Ungulata” (various supraordinal ranks) has included:
Cetacea: whales
Artiodactyla: even-toed ungulates
Perissodactyla: odd-toed ungulates
Hyracoidea: hyraxes
Proboscidea: elephants
Sirenia: manatees & dugongs
Tubulidentata: aardvarks
Various fossil orders...
arctocyonid condyarths
artiodactyls
mesonychian condyarths
whales?
Ambulocetus (“the walking and swimming whale”)
Eocene
Evolution
Phylogeny
“whippo”
hypothesis
Morphology
Molecules
“whippo” synapomorphies?
•nearly hairless bodies
•absence of sebaceous glands
•thick layer of insulating fat
•offspring nurse while submerged
•lack of scrotal testes
•general aquatic habit
•vocalize/communicate underwater
“Whales originated from
aquatic artiodactyls in the
Eocene epoch of India”
Thewissen et al. 2007
“Whales originated from
aquatic artiodactyls in the
Eocene epoch of India”
Thewissen et al. 2007
Artiocetus (“deer whale”)
47 MYA, Pakistan
Nares well-forward on dorsal
surface
Gingerich et al., 2001, Science
Rhodocetus
Aquatic
Webbed hands and feet
Quadrupedal paddler
Robust tail for undulation
Artiocetus hind limb
Rhodocetus
Astragalus
Cuboid
pes
Stiff webbed foot
manus
Protocetidae
Characters of Protocetids
* laterally facing orbits
covered by supraorbital shield
* legs shortened to
streamline body
* sacrum composed of four
or fewer vertebrae
Rodhocetus
Mid. Eocene (46 mya)
* P4/ larger than M1/ in
occlusal outline
* retention of M3/
Whales & dolphins
Artiodactyls
Artiodactyls
Carnivorans
Pangolins
Perissodactyls
Bats
Solenodons
Moles
Shrews
Hedgehogs
Primates
Treeshrews
Colugos
Lagomorphs
Rodents
Xenarthrans
Golden moles
Tenrecs
Elephant shrews
Aardvarks
Dugongs & manatees
Hyraxes
Elephants
“Cetartiodactyla”
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