Which of the following vertebrate groups includes more number of extant species than the others?

Options

A. Mammalia
B. pisces
C. aves
D. Retilia

Answer

To determine which vertebrate group includes more extant species than the others, we can analyze the options provided: Mammalia, Pisces, Aves, and Reptilia.

### Step-by-Step Solution:

1. **Understanding the Groups**:
- **Pisces**: This group includes fish, which can be divided into two main categories: Chondrichthyes (cartilaginous fish like sharks and rays) and Osteichthyes (bony fish).
- **Aves**: This group consists of birds, which are considered avian dinosaurs.
- **Reptilia**: This group includes reptiles such as snakes, lizards, and turtles.
- **Mammalia**: This group includes mammals, which are characterized by the presence of mammary glands.

2. **Extinction Rates**:
- **Pisces**: Historically, fish have experienced high extinction rates. A significant percentage of fish species have gone extinct over time, with studies suggesting that up to 95% of ancient fish species are no longer extant.
- **Aves**: The extinction of dinosaurs led to a significant loss of species within this group, but many bird species still exist today.
- **Reptilia**: Similar to Aves, reptiles also faced extinction during the dinosaur extinction event, but many species remain.
- **Mammalia**: This group has the least number of extinctions compared to the others, with approximately 6,500 species having gone extinct.

3. **Current Extant Species**:
- **Pisces**: Despite the high number of extinct species, there are still many extant fish species.
- **Aves**: There are approximately 10,000 extant bird species.
- **Reptilia**: There are around 10,000 extant reptile species.
- **Mammalia**: There are about 6,500 extant mammal species.

4. **Comparison of Extant Species**:
- Comparing the extant species of each group, we find that both Aves and Reptilia have a similar number of extant species, which is higher than Mammalia. However, Pisces, while having a high number of extinct species, still has a significant number of extant species.

5. **Conclusion**:
- After analyzing the extinction rates and the current number of extant species, we conclude that the group with the highest number of extant species is **Aves** (birds) and **Reptilia** (reptiles), while **Pisces** has a high number of extinct species.

### Final Answer:
The vertebrate group that includes more number of extant species than the others is **Aves**.