Question

What are the important changes in the evolution of the modern horse from the Eohippus (ancestral horse)?

Answer 1

1. Increase in body size and height: Eohippus was about 30 cm tall, while the modern horse is much taller by approximately 135 cm.
2. Lengthening of head and neck: The modern horse has a longer head and neck compared to the ancestral form.
3. Modification of limbs:
   • The number of digits was reduced from four in the forelimbs and three in the hind limbs of Eohippus to a single functional digit in modern horses.
   • The ulna and fibula bones are reduced in modern horses.
4. Change in foot posture: The foot posture changed from plantigrade (walking on the whole foot) in Eohippus to unguligrade (walking on the tip of the toe) in modern horses, improving their speed and efficiency for running.
5. Changes in teeth: The length and shape of cheek teeth changed from those suitable for browsing (eating shrubs and leaves) in Eohippus to those adapted for grazing (eating grass) in modern horses.
6. Adaptation to environment: These changes occurred in response to environmental shifts, from dense forests to open grasslands, favoring a long-legged, swift animal suited for running over hard grounds.