Question

In the context of phylogeny of horses, the CORRECT chronological order from old to young is

• A. Hyracotherium, Mesohippus, Merychippus, Equus
• B. Hyracotherium, Merychippus, Mesohippus, Equus
• C. Equus, Merychippus, Mesohippus, Hyracotherium
• D. Merychippus, Equus, Mesohippus, Hyracotherium

Hint:

Mnemonic: “Happy Men Make Excitement” — Hyracotherium → Mesohippus → Merychippus → Equus.

Answer 1

The Correct Option is A

Step 1: Understanding horse evolution.
The evolution of horses shows a gradual increase in body size, reduction in toes, and development of high-crowned teeth suited for grazing.
Step 2: Sequence.
- Hyracotherium (Eohippus): Earliest horse (Eocene).
- Mesohippus: Oligocene — three-toed form.
- Merychippus: Miocene — development of grazing teeth.
- Equus: Pleistocene to Recent — modern single-toed horse.
Step 3: Conclusion.
Hence, the correct chronological order is Hyracotherium → Mesohippus → Merychippus → Equus.