BASC107A- Origin and Developmnent of the Horse
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Questions and Answers

Which digit was enlarged and developed in the horse during its evolution?

  • First digit (thumb)
  • Second digit
  • Third digit (median) (correct)
  • Fifth digit

    • What structural change in the horse's limbs aided in faster running?

  • Lengthening of forearm
  • Lengthening of limbs and perfection of hoof (correct)
  • Elongation of femur
  • Reduction of radial bone

    • Which bone reduction in the hind limb contributed to the horse's evolutionary adaptation?

  • Reduction of the patella
  • Reduction of the femur
  • Reduction of the fibula and strengthening of the radius
  • Reduction of the fibula and strengthening of the tibia (correct)

    • What significant locomotion change occurred in horse evolution?

    <p>From digitigrade to unguligrade</p> Signup and view all the answers

    Which skull trait developed to support a larger brain in horses?

    <p>Increase in size and complexity of the brain</p> Signup and view all the answers

    To which order do horses belong?

    <p>Perissodactyla</p> Signup and view all the answers

    Which genus includes horses, zebras, and asses?

    <p>Equus</p> Signup and view all the answers

    During which epoch did the very first horse evolve?

    <p>Eocene</p> Signup and view all the answers

    Which category of the scientific classification does 'Chordata' refer to for horses?

    <p>Phylum</p> Signup and view all the answers

    Which animals are included in the order Perissodactyla along with horses?

    <p>Rhinos and tapirs</p> Signup and view all the answers

    Which of the following horse ancestors existed 60 million years ago?

    <p>Hyracotherium</p> Signup and view all the answers

    Which horse ancestor was slightly larger than Eohippus and had 3 toes?

    <p>Mesohippus</p> Signup and view all the answers

    Which horse ancestor had a single toe that developed into a hoof and could run faster?

    <p>Merychippus</p> Signup and view all the answers

    What is the earliest known ancestor of the horse?

    <p>Hyracotherium</p> Signup and view all the answers

    Which horse ancestor lived on grasslands approximately 5 million years ago?

    <p>Pliohippus</p> Signup and view all the answers

    During which geological epoch did Mesohippus live?

    <p>Oligocene</p> Signup and view all the answers

    Which horse ancestor is characterized by having four toes well spread for walking on soft ground?

    <p>Hyracotherium</p> Signup and view all the answers

    How many toes did the front feet of Eohippus have?

    <p>Four</p> Signup and view all the answers

    Which feature is common in the modern horse Equus?

    <p>Single hoof</p> Signup and view all the answers

    Which of the following ancestors of the horse is known for having lived between 23 and 2 million years ago and was well adapted to grasslands?

    <p>Hipparion</p> Signup and view all the answers

    Which characteristic is true of Mesohippus?

    <p>Had six grinding cheek teeth with a premolar in front</p> Signup and view all the answers

    What was the main function of the toes of Eohippus?

    <p>To keep the feet off the ground and bear the animal's weight</p> Signup and view all the answers

    Which ancestor of the horse still survives today in a wild form similar to Equus but with distinct features?

    <p>Przewalski horse</p> Signup and view all the answers

    Which statement is true about the dentition of Eohippus?

    <p>They had low-crowned and low-cusped teeth for soft vegetation</p> Signup and view all the answers

    What evolutionary change is evident in Mesohippus compared to Eohippus?

    <p>Elongation of face, snout, and neck</p> Signup and view all the answers

    Approximately how tall was Eohippus?

    <p>14 inches</p> Signup and view all the answers

    Which evolutionary stage of the horse had longer legs and neck compared to other species?

    <p>Eohippus</p> Signup and view all the answers

    Which horse species lived during the Miocene Epoch about 30 million years ago?

    <p>Merychippus</p> Signup and view all the answers

    What feature made Pliohippus's teeth better suited for eating grass?

    <p>Teeth became better fitted for eating grass</p> Signup and view all the answers

    Which evolutionary stage of the horse was an effective grazer and runner?

    <p>Merychippus</p> Signup and view all the answers

    Which stage of the horse evolution had three toes on each foot where the middle toe was long and useful?

    <p>Merychippus</p> Signup and view all the answers

    During which epoch did Pliohippus live?

    <p>Pliocene</p> Signup and view all the answers

    Which prehistoric horse is considered directly linked to the genus Equus?

    <p>Pliohippus</p> Signup and view all the answers

    In what regions have fossils of Pliohippus been found?

    <p>Great Plains of the US and Canada</p> Signup and view all the answers

    What significant change occurred in the horse's body modification during its evolution?

    <p>Increased in size and height</p> Signup and view all the answers

    Which characteristic distinguishes Equus from its predecessor Pliohippus?

    <p>Does not have a dished face</p> Signup and view all the answers

    What are some uses of the modern-day horse, Equus, that continue from 3000 years ago?

    <p>Travel</p> Signup and view all the answers

    Study Notes

    Early Evolution of Horses

    • Eohippus (50 million years ago): small, 4-toed, lived in forests, about the size of a cat or a dog, with an arched back and snout-like nose
    • Eohippus had a dentition adapted to feed on soft vegetation, with 4 toes on the front feet and 5 toes on the hind feet, with the 1st and 5th toes not touching the ground
    • Hyracotherium (60 million years ago): the ancestor of the horse, with a similar size and characteristics to Eohippus

    Evolutionary Stages

    • Mesohippus (35 million years ago): slightly larger than Eohippus, with 3 toes, and a stronger middle toe
    • Merychippus (10 million years ago): larger, with a single toe, and a hoof, lived on grasslands
    • Pliohippus (5 million years ago): single-toed or hooved, with strong leg ligaments for increased speed and power, and a dished face
    • Equus (present): the modern horse, evolved from Pliohippus, with a single hoof, long legs, and a fast runner

    Key Characteristics

    • Increase in size and height over time, from rabbit-like to 6-feet grassland animal
    • Lengthening of limbs and perfection of hoof for fast running in grasslands
    • Enlargement and development of the 3rd digit (median) and reduction of the lateral digits
    • Reduction of the ulna (fore) and fibula (hind) and strengthening of radius and tibia
    • Change from digitigrade to unguligrade locomotion for fast running

    Body Modifications

    • Increase in size and height, from rabbit-like to 6-feet grassland animal
    • Development of the hooves and leg ligaments for increased speed and power

    Evolution

    • Evolution means change, a dynamic process full of twists, transitions, and dead ends (extinctions)
    • Result of genetic adaptation to environmental changes
    • Horses belong to the order Perissodactyla, the odd-toed ungulates, which includes horses, rhinos, and tapirs today

    Scientific Classification of Horse

    • Kingdom: Animalia
    • Phylum: Chordata
    • Class: Mammalia
    • Order: Perissodactyla
    • Genus: Equus, which includes horses, zebras, and asses

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    Description

    This quiz covers the early evolution of the horse, from Eohippus to Equus, including the stages of development and the characteristics of each horse ancestor.

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