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PERISSODACTYLA Mammalogy EEOB 625 3 March 2004

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Cheetah. l. l. m. m. Lever arm ratios (R): m = joint to ... Cheetah: R = 0.2. Power vs Speed of Movement. Cannon bone & Springing ligament. PERISSODACTYLA: ... – PowerPoint PPT presentation

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Title: PERISSODACTYLA Mammalogy EEOB 625 3 March 2004


1
PERISSODACTYLAMammalogy EEOB 625 -3 March
2004
  • The Origin Adaptive Radiation of Ungulates
  • Order Condylartha dominant "Ungulates of the
    Paleocene
  • Ancestral to Perissodactyla, Artiodactyla,
  • Subungulates and
    Cetacea
  • Coevolution of Ungulates with
  • Food Woody plants, forbs, and grasses
  • Predators Arms race of size speed

2
Coevolutionary Factors in the Adaptive Radiation
of Ungulates
  • Climate Change in the early Cenozoic
  • Progressive cooling drying of continents
  • Loss of forests expansion of prairies
  • Grasses Origin (Oligocene) and radiation
  • Anti-grazing defenses of grasses
  • - growth from the base, near the roots
  • - silica in the cell wall increases the
  • cost of mastication

3
Adaptations for Cellulose Digestion
  • Plant anatomy Cell wall, cell membrane, and
    cytoplasm with protein carbohydrates
  • Dental adaptations for mastication of cell walls
    and lignified plant structures
  • 1) the hypsodont (high crowned) molar,
  • ever growing or rootless in some
    species
  • 2) Selenodont occlusal surface a rasping,
  • grinding surface, highly resistant to
    wear
  • Digestive Adaptations Cecum rumen

4
Evolution of the hypsodont molar
hypsodont
bunodont selenodont
5
Ungulate Adaptations for Locomotion
  • Selection for mass, mobility, speed
  • Determinants of speed
  • length of stride rate of striding
  • Adaptations for long stride
  • - lengthening of metacarpals metatarsals
  • - free swing of the scapula
  • - flexible vertebral column

6
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7
Ungulate Adaptations for Locomotion
  • Determinants of running speed
  • length of stride rate of striding
  • Adaptations for high stride rate
  • - reduction of mass of distal limb elements
  • - cannon bone springing ligament
  • - short lever arms for high gear muscles
  • - summing velocities of many limb segments

8
Power vs Speed of Movement
Cheetah
Badger
Lever arm ratios (R) m joint to insertion l
joint to ground
m
10 cm
m
6 cm
Badger R 0.4
l
15 cm
l
50 cm
Cheetah R 0.2
9
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10
Cannon bone Springing ligament
11
PERISSODACTYLA A clade defined by the
mesaxony,
  • Mesaxonic? Weight-bearing axis through digit 3
  • Early descendants of Condylartha
  • Eocene radiation, decline in late Oligocene
  • Evolution of the horse in N. America
  • A classic phylogeny, but what is wrong with
    this picture?
  • Trends and misconceptions regarding equid
    evolution Compare Text Figs.

12
Mesaxonic For meso i.e., middle
13
PERISSODACTYLA Systematics
  • Mesaxonic ?
  • Early descendants of Condylartha
  • Eocene radiation, decline in late Oligocene
  • Evolution of the horse in N. America
  • Three Extant families
  • Equidae, Tapiridae Rhinocerotidae

14
J.Z. Young
15
Fig. 19.2, Feldhamer
16
Fig 19.4,Feldhamer
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