Consider the following characteristics (a) 120 cm high at shoulders (b) Forelimb and hindlimb had one compelete finger and toe and two hidden splints (c) evolved from Mercychippus (d) Teeth adapted for eating grass which of the following ancestral horse is best described by the above mentioned chraracteristics?

Options

A. Pilohiphhus
B. Mesohippus
C. Hyracotherium
D. Callipus

Answer

To solve the question regarding the characteristics of an ancestral horse, we will analyze each characteristic step by step and determine which horse best fits the description.

### Step-by-Step Solution:

1. **Analyzing the Height**:
- The first characteristic states that the horse is "120 cm high at shoulders." This suggests a relatively large size compared to earlier horse ancestors.

**Hint**: Consider the size of various horse ancestors and how they compare to modern horses.

2. **Examining the Limbs**:
- The second characteristic mentions that the forelimb and hindlimb had "one complete finger and toe and two hidden splints." This indicates a transition from multi-toed ancestors to a more modern single-toed structure, which is a significant evolutionary step.

**Hint**: Think about the evolution of horse limbs and how they changed over time.

3. **Evolutionary Background**:
- The third characteristic states that this horse "evolved from Merikippus." This is crucial as it helps narrow down the options to those that directly descended from Merikippus.

**Hint**: Identify which horse species are known to have evolved from Merikippus.

4. **Dietary Adaptations**:
- The fourth characteristic indicates that the teeth are "adapted for eating grass." This suggests that the horse was likely adapted to a grazing lifestyle, which is common in later horse species.

**Hint**: Consider the dietary needs of horses and how their teeth evolved to accommodate those needs.

5. **Identifying the Correct Horse**:
- Based on the analysis of the characteristics:
- The height of 120 cm suggests a larger horse.
- The limb structure indicates a transition towards modern horses.
- The evolutionary link to Merikippus is key.
- The adaptation for grass-eating points towards a later evolutionary stage.

The horse that best fits all these characteristics is **Leohippus**. Leohippus is known to have evolved from Merikippus, had a height around 120 cm, featured a complete digit structure, and had teeth adapted for grazing.

### Final Answer:
The ancestral horse best described by the above-mentioned characteristics is **Leohippus**.

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