17 - Perissodactyla

nicolepridemore
Mind Map by nicolepridemore, updated more than 1 year ago
nicolepridemore
Created by nicolepridemore over 6 years ago
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Description

Mammalogy (Final Exam) Mind Map on 17 - Perissodactyla, created by nicolepridemore on 04/27/2015.

Resource summary

17 - Perissodactyla

Annotations:

  • large, hoofed, terrestrial herbivores 
  • walk around on tips of toes 
  • hard, KERATINIZED hooves
  • limbs move in single plane because of pulley-like ASTRAGALUS in ankle 
  • cursorial locomotion 
  • usually HYPSODONT dentition 
  • morphology and life histories typically suited for open habitats 
  • efficient feeding and outrunning predators 
  • ungulate distribution limited by forage 
  • morphology of forage the result of pressures of ungulates over evolutionary time 
  • ungulates = the most IMPORTANT group of mammals to humans for commerce and economics 
  • domestication, sport hunting, ecotourism 
  • perissodactyls today much LESS diverse than artiodactyls 
  • a switch from 50 mya, when they far outnumbered smaller, less diverse artiodactyles 
  • MONOPHYLETIC group
  • 3 families, 6 genera, 16 species 
  • horses, asses, zebras, tapirs, rhinos 
  • formerly much more DIVERSE 
  • oldest identifiable perissodactyl fossils from late Paleocene (55 mya) 
  1. characteristics

    Annotations:

    • adapted to UNGULIGRADE (hoofs) CURSORIAL locomotion
    • clavicle ABSENT 
    • group defined by FOOT structure 
    • odd-toed ungulates 
    • only ONE functional digit on each foot, weight borne on middle digit - the LARGEST 
    • tapirs with 4 digits on front, 3 on hind, 3 on each in rhinos, 3rd digit the only one on HORSES 
    • cannot bend hindlimbs enough to get up hindfeet first when laying on ground 
    • elongate skull with long ROSTRUM
    • large molars and premolars, typically HYPSODONT and LOPHODONT for grazing lifestyle 
    • diastema between incisors and cheekteeth 
    • no true HORNS or ANTLERS 
    • rhino "horn" lacks bony core and keratinized sheath; a dermal mass of agglutinised, keratinized fibers (fused hairs) 
    1. evolutionary/fossil history

      Annotations:

      • arose in late PALEOCENE in Asia
      • Rhinos evolved in Eurasia and North America in early Eocene 
      • largest known land mammal = PARACERATHERIUM (5 meters tall, 11,000 kg)
      • tapirs evolved in North America in EOCENE
      • dominant browsers of Eocene 
      • began to decline in Miocene (climatic changes, competition with artiodactyls) 
      • horses evolved in North America in early EOCENE
      1. cursorial locomotion adaptations

        Annotations:

        • integrated LOCOMOTOR and RESPIRATORY functions
        • synchronize breathing with stride cycles 
        • tracheal valving shunts air from side to side between lungs
        • slim, elongate legs 
        • muscles positioned near body 
        • tendons DISTALLY 
        • long legs
        • metacarpals and metatarsals elongate 
        • LOSS or REDUCTION of clavicle 
        • FLEXION and EXTENSION of spine
        • increase number of moveable joints in limb
        • only hoof-bearing TIPS of digits contact ground
        • ASTRAGALUS rests on distal tarsal bones 
        • tarsals modified by loss or fusion of elements 
        • weight transferred to central digits 
        • SPRINGING ligament in feet 
        • NUCHAL ligament supports weight of head 
        1. feeding specializations

          Annotations:

          • herbivorous
          • simple stomach, but large CECUM for microorganism-facilitated breakdown of cellulose 
          • molariform cheek teeth with large complex occlusal surfaces 
          • food retained shorter period than for ruminant artiodactyls 
          • less efficient and must consume LARGER amounts than ruminants 
          1. economics & conservation

            Annotations:

            • horses domesticated ~4,500 years ago in Central Asia 
            • second only to CATTLE in importance to human development or cultural and economic systems 
            • travel, exploration, warfare, agriculture 
            • domestic horses doing VERY WELL (introductions)
            • other perissodactyls in trouble (human interference, poaching rhino horns, habitat destruction)
            • African ass and quagga recently extinct
            • Onager, Przewalski's horse, Grevy's and mountain zebra endangered 
            • mountain tapir endangered 
            • all rhinos endangered or vulnerable 
            1. families
              1. Equidae

                Annotations:

                • most species are HIGHLY social
                • form herds and/or clans
                • polygynous mating system
                • social hierarchy - led by DOMINANT stallion 
                • HAREMS formed in some species 
                • bachelor species 
                • complex behavior and vocal communication 
                • fission-fusion social system common 
                1. Tapiridae

                  Annotations:

                  • Stocky build (weigh up to 320 kilograms) 
                  • short, flexible (proboscis)
                  • limbs short and stout 
                  • 4 toes on front, 3 toes on hind feet 
                  • brachyodont cheek teeth 
                  • nasal bones of skull RETRACTED - above orbits 
                  1. Rhinocerotidae

                    Annotations:

                    • large, heavy-bodied, short-legged
                    • graviportal limbs 
                    • weigh up to 2,800 kg
                    • 3 or 4 toes on front foot, 3 toes on hind foot 
                    • nasal bones THICKENED and enlarged 
                    • supported horn of dermal material 
                    • use of horns in traditional Eastern "medicine" and more recently sprinkled in alcoholic cocktails 
                    • $75,000 per kg (twice the value of gold) 
                    • 90% decrease in number of wild rhinos today compared to 1970
                    • critically threatened - 35 Javan rhinos, ~100 Sumatran, and <5,000 black rhinos 
                    • near threatened - ~20,000 white rhinos 
                    • vulnerable - as few as 600 greater one-horned rhinos in 1976, increased since then 
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