Title: PERISSODACTYLA Mammalogy EEOB 625 3 March 2004
1PERISSODACTYLAMammalogy 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
2Coevolutionary 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
3Adaptations 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
4Evolution of the hypsodont molar
hypsodont
bunodont selenodont
5Ungulate 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
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7Ungulate 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
8Power 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
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10Cannon bone Springing ligament
11PERISSODACTYLA 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.
12Mesaxonic For meso i.e., middle
13PERISSODACTYLA 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
14J.Z. Young
15Fig. 19.2, Feldhamer
16Fig 19.4,Feldhamer