There has been an increase in the number of chambers in heart during evolution of vertebrates. Give the names of the class of vertebrates having two, three or four chambered heart.

Explanation

To answer the question about the evolution of heart chambers in vertebrates, we can categorize the classes of vertebrates based on the number of chambers in their hearts as follows:

### Step-by-Step Solution:

1. **Identify the Classes of Vertebrates**:
- The main classes of vertebrates include Pisces (fish), Amphibia (amphibians), Reptilia (reptiles), Aves (birds), and Mammalia (mammals).

2. **Two-Chambered Heart**:
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