Phylogenetic tree illustrating the evolutionary relationship between a leopard and a domestic cat.

Problem Overview:

The task involves constructing a phylogenetic tree for a group of animals based on their physical characteristics. Phylogenetic trees are used to represent evolutionary relationships among species, showing how they are related through common ancestors.

#### Key Concepts:
1. Phylogenetic Tree: A branching diagram that represents the evolutionary history and relationships among organisms.
2. Characters: Traits or features used to determine evolutionary relationships (e.g., physical structure, genetic sequences).
3. Clades: Groups of organisms that include a common ancestor and all its descendants.

#### Given Information:
- The task requires using physical characteristics to construct the phylogenetic tree.
- Example characters mentioned: body shape, musculature, etc.
- The goal is to classify a group of animals into clades based on shared traits.

---

Solution Approach:

#### Step 1: Identify the Animals
From the context, the animals mentioned in the problem are:
- Leopard
- Domestic cat
- Common ancestor

These will be the focal points for constructing the phylogenetic tree.

#### Step 2: Choose Physical Characteristics
We need to select physical characteristics that can help differentiate these animals and group them into clades. Some possible characteristics include:
1. Body Shape: Leopards and domestic cats have similar body shapes (carnivorous, quadrupedal).
2. Musculature: Both leopards and domestic cats have strong musculature adapted for hunting.
3. Size: Leopards are significantly larger than domestic cats.
4. Habitat: Both are terrestrial but may differ in specific habitats (e.g., savannas vs. urban areas).

For simplicity, let’s use the following characteristics:
- Presence of a tailbone: Both leopards and domestic cats have tails.
- Cold or warm-blooded: Both are warm-blooded mammals.
- Presence of fur/hair: Both have fur.

#### Step 3: Construct the Phylogenetic Tree
Using the chosen characteristics, we can group the animals into clades. Here’s how the tree might look:

1. Common Ancestor: At the base of the tree, representing the shared ancestor of both leopards and domestic cats.
2. Shared Characteristics:
- Both leopards and domestic cats share traits like being warm-blooded, having fur, and possessing a tailbone.
3. Differences:
- Size: Leopards are much larger.
- Habitat: Leopards typically inhabit savannas and forests, while domestic cats are adapted to human environments.

#### Phylogenetic Tree Structure:
```
Common Ancestor
|
+------+------+
| |
Leopard Domestic Cat
```

#### Step 4: Explanation
- The common ancestor is placed at the root of the tree, as it is the shared ancestor of both leopards and domestic cats.
- Both leopards and domestic cats branch off from this common ancestor because they share many physical characteristics (e.g., warm-blooded, fur, tailbone).
- Despite differences in size and habitat, these animals are grouped together due to their shared evolutionary traits.

---

Final Answer:

The phylogenetic tree for the given animals based on physical characteristics is:

```
Common Ancestor
|
+------+------+
| |
Leopard Domestic Cat
```

This tree reflects their evolutionary relationship, with both species sharing a common ancestor and branching off due to speciation events over time.

Boxed Answer:
\[
\boxed{
\text{See the phylogenetic tree above.}
}
\]