How many times is the modern horse taller than its earliest ancestor? Show your working.

The modern horse (Equus) has a height of $1.6 \text{ m}$.
The earliest ancestor (Hyracotherium) has a height of $0.4 \text{ m}$.

The modern horse is 4 times taller than its earliest ancestor.

2.2.2)
Over time, the number of toes on the horse's front leg reduced from multiple toes to a single, central toe that developed into a hoof. The leg also became longer and more adapted for running.

2.2.3)
One way the modern horse is adapted to open grassland is the development of a single hoof on each foot. This adaptation allows for greater speed and efficiency when running on hard, open ground, which is crucial for escaping predators in a grassland environment.