figure 20-2. figure 01: one phylogenetic hypothesis of the evolutionary relationships among the...
TRANSCRIPT
Figure 20-2
FIGURE 01: One phylogenetic hypothesis of the evolutionary relationships among the Afrotheria
Adapted from Nishihara, H., et al., Mol Biol Evol. 22 (2005): 1823-1833 and Seiffert, E.R., BMC Evol Biol. 7 (2007): 1-13.
Macroscelidea
Long, mobile snout Long, slender legs adapted for running Large eyes and prominent ears Complete auditory bulla Complete zygoma
Family Macroscelididae (elephant-shrews)
Subclass Theria Infraclass Eutheria
• Order Macroscelidea (elephant-shrews) 4 genera / 19 species (4/16) Fossils date to Eocene of northern Afri New species discovered in Tanzania in 2007 Africa
Some with 3 digits on hind foot Short fleshy proboscis, large ears and eyes 1-3/3, 1/1, 4/4, 2/2-3 = 36-42
Macroscelidea
Inhabit open plains to tropical forests Largely insectivorous Some species strikingly colored Territorial—may maintain intricate trail system Scent marking and foot drumming Some species use behavioral
thermoregulation (basking)
Tenrecidae (tenrecs)
Subclass Theria Infraclass Eutheria
• Order Afrosoricida (tenrecs and golden moles)
10 genera / 24 species west-central Africa & Madagascar P1 absent, M usually 3/3
• one with stridulating organ (Hemicentetes)
Chrysochloridae (golden moles)
Subclass Theria Infraclass Eutheria
• Order Afrosoricida (tenrecs and golden moles)
7 genera / 18 species southern Africa 3/3 1/1 3/3 3/3 = 40
No “W-shaped” ectolophs 3/3 1/1 3/3 3/3 = 40
Family Orycteropodidae (aardvark)
Subclass Theria Infraclass Eutheria
Order Tubulidentata (aardvark) 1 genus / 1 species African savannahs Fossils appear in Miocene of southern Europe,
Middle East, and Africa Termite eaters, thick skinned, strong claws Long protrusible tongue 0/0 0/0 2-3/2 3/3 = 20-22
Tubulidentata Skull elongate
Dentary bone long and slender
Adults lack incisors and canines
Cheekteeth are rootless, columnar, and lack enamel
Teeth made of hexagonal prisms of dentine
Tongue is long and protrusible
Tubulidentata
Dismantle termite mounds with powerful forelimbs
Burrow rapidly for protection
Aardvark burrows used as retreats by many other mammals
Also eat fruits of cucurbit plant (Cucumis) or “aardvark cucumber”—may be symbiotic
Tubulidentata
Olfaction well-developed
Fleshy tentacles on nasal septum
Adapted from Kingdon, J. The Kingdon Field Guide to African Mammals. Princeton University Press, 1997.
FIGURE 13: The complex nose of an aardvark (Orycteropus afer)
Tubulidentata
Courtesy of A. Taylor
FIGURE 11:An aardvark
(Orycteropus afer, Orycteropodidae)
Tubulidentata
FIGURE 12: The skull of the aardvarkAdapted from Hatt, R. T., Bull. Amer. Mus. Nat. Hist. 66 (1934): 643-672.
FIGURE 01: One phylogenetic hypothesis of the evolutionary relationships among the Afrotheria
Adapted from Nishihara, H., et al., Mol Biol Evol. 22 (2005): 1823-1833 and Seiffert, E.R., BMC Evol Biol. 7 (2007): 1-13.
Paenungulata
Order Proboscidea—Elephants
Order Sirenia—Manatees and sea cows
Order Hyracoidea—Hyraxes
Paenungulata
Adapted from Seiffert, E.R., BMC Evol Biol. 7 (2007): 224 and Nishihara, H., et al., Mol Biol Evol. 22 (2005):1823-1833.
FIGURE 01: Two possible phylogenies of the Paenungulata
Order Proboscidea
Elephants Fossil record begins in Eocene of North Africa
Diverse in late Eocene
Large size
Columnar limbs and graviportal locomotion
Expanded out of Africa in late Oligocene
Reached North America in Miocene
Proboscidea
Major trends in evolution:
Columnar limbs
Enlarged skull and reduced neck
Elongate proboscis or trunk
Incisors become tusk-like
Numerous cross lophs on cheek teeth
Anterior replacement of cheek teeth
Adapted from Shoshani, J., Natural History 106 (1997): 36-47.
FIGURE 02: One family tree of probocideans from the Eocene to the present
Family Elephantidae (elephants)
Subclass Theria Infraclass Eutheria
• Order Proboscidea (elephants) 2 genera / 2 species Sub-Saharan Africa, India, Nepal, & SE Asia
Tusks from upper incissors long fleshy proboscis 3/3 Mammoths extinct
Family Elephantidae
Feed on trees, shrubs, and grasses Highly social
Matriarchal kinship groups Matriarch plus related females and young Communicate using infrasound over long
distances Audible, tactile, and visual communication at
short range
Family Elephantidae
Adult male elephants form bachelor herds or are solitary
Musth—periods of heightened aggression and sexual activity
Family Elephantidae
Largest living land mammals (up to 6,000 kg)
Long, muscular trunk Large ears (smaller in
Elephas) Digitigrade posture with
dense heel pad
FIGURE 06: The bone of the right hind foot of Mammut, a late Tertiary
and Pleistocene proboscidean
Modified from Romer, A.S. Vertebrate Paleontology. University of Chicago Press, 1966.
Elephant Tooth Replacement
Adapted from Kingdon, J. The Kingdon Field Guide to African Mammals. Princeton University Press, 1997.
FIGURE 07A: The occlusal surface of a molar of the Asian elephant (Elephas maximus)
Family Elephantidae
Skull foreshortened Skull contains large air sinuses
Modified from Romer, A.S. Vertebrate Paleontology. University of Chicago Press, 1966.
FIGURE 04: The skull of Mammuthus, a
Pleistocene elephantid
Order Sirenia
Dugongs and manatees
Completely aquatic herbivores
2 genera and 4 species
5th species, Steller’s sea cow (Hydrodamalis gigas), became extinct in 1768
Fossils date to early Eocene of Jamaica
Still capable of terrestrial locomotion
Order Sirenia
Weights above 1,500 kilograms Nearly hairless, thick skin Nostrils valvular Thick dentary bone Middle ear bones are massive Dense, heavy bones provide ballast
Order Sirenia
Five-toes manus enclosed in flipper Pelvis vestigial, hind limbs absent Tail is horizontal fluke Cheekteeth large, columnar, and covered
with cementum (dugongs) or covered with enamel (manatees)
Tooth replacement similar to elephants
Order Sirenia
FIGURE T01: Comparison of Characteristics of Two Sirenian Families
Family Dugongidae (dugong & sea cow)
Subclass Theria Infraclass Eutheria
• Order Sirenia (dugongs, manatees, and sea cows)
1 genus / 2 species Coasts of E Africa, Asia Phillipines, & Australia
Lack vestigal nails on flippers Notched flukes 2/3, 0/1, 3/3, 3/3 = 36 Up to 3.5 m Stellar’s Sea Cow lived in Bering Sea
Family Trichechidae (manatees)
Subclass Theria Infraclass Eutheria
• Order Sirenia (dugongs, manatees, and sea cows)
1 genus / 3 species Coasts of SE US, West Indies, South America
(Orinoco & Amazon) vestigal nails on flippers rounded flukes 6 present at any time, indefinite number Up to 4 m
Order Sirenia
FIGURE 11: The skull of a manatee; length of skull 360
millimetersAdapted from E. Raymond and Kelson Keith Hall. Mammals of North America, Volume 2. John Wiley & Sons Ltd., 1959.
Family Procaviidae (hyraxes)
Subclass Theria Infraclass Eutheria
• Order Hyracoidea (hyraxes) 3 genera / 7 species (3/4) Sub-Saharan Africa & Middle East
Earliest fossils from Eocene of Morocco Weird 3 digits (hind) with almost hoof-like nails Pads of feet moistened by sweat glands 1/2, 0/0, 4/4, 3/3 = 34
Order Hyracoidea
FIGURE 15A: Two Procavia capensis (above) and two
Heterohyrax brucei (below) basking with their bodies broadside to the
early morning sun
Courtesy of Dr. Hendrik Hoeck
FIGURE 15B: Hyraxes of both species huddled together on a
cool day
Courtesy of Dr. Hendrik Hoeck
Order Hyracoidea
Rabbit-sized Deep mandible Incisors ever-growing Diastema present Four toes on forefeet; three toes on hind feet Feet mesaxonic Digits of pes bear flattened nails (except
clawed second digit)
Adapted from Hatt, R. T., Bull. Amer. Mus. Nat. Hist. 72 (1936): 117-141.
Order Hyracoidea
Herbivorous (caecal fermentation)
Prefer rocky outcrops (trees for Dendrohyrax)
Diurnal with polygynous family groups
Heterohyrax and Procavia share rock outcrops and share nurseries (mixed groups of young)
Use behavioral thermoregulation (basking)
Order Hyracoidea
Both photos courtesy of Dr. Hendrik HoeckFIGURE 14: The sole (A) and dorsum (B) of the
hind foot of a tree hyrax (Dendrohyrax sp.)
Figure 20-2
Megalonychidae (two-toed sloths)
Subclass Theria Infraclass Eutheria
• Order Pilosa (edentates) 1 genus / 2 species Central America & N South America 0/0 0/0 PM 5/4- 5 = 18-20
syndactylus
Bradypodidae (three-toed sloths)
Subclass Theria Infraclass Eutheria
• Order Pilosa (edentates) 1 genus / 3 species Cantral America & N South America 0/0 0/0 PM 5/4- 5 = 18-20, no enamel
Zygomatic arch incomplete
Family Cyclopedidae (silky anteaters)
Subclass Theria Infraclass Eutheria
• Order Pilosa (edentates) 1 genus / 1 species S Mexico to Bolivia arboreal
Family Myrmecophagidae (anteaters)
Subclass Theria Infraclass Eutheria
• Order Pilosa (edentates) 3 genera / 4 species Central & South America terrestrial
Family Dasypodidae (armadillos)
Subclass Theria Infraclass Eutheria
• Order Cingulata (armadillos) 8 genera / 20 species North, Central & N South America homodont, 7/7 to 18/19
4 identical quadruplets
