What is sequence in the evolution of mammals?

Options

A. Fish-amphibian-bird-mammals
B. Insect-fish bird-mammals
C. Fish-amphibian-reptile-mammals
D. Fish-amphibian-reptile-bird-mammals

Answer

To understand the sequence of evolution of mammals, we need to trace the lineage from the earliest vertebrates to the mammals we see today. Here’s a step-by-step breakdown of the evolutionary sequence:

### Step 1: Origin of Fish
- The earliest vertebrates were fish. They evolved in aquatic environments and are characterized by having fins, scales, and gills.

### Step 2: Evolution of Amphibians
- From fish, the next significant evolutionary step was the emergence of amphibians. Amphibians evolved from fish and are adapted to live both in water and on land. They typically have four legs and smooth skin, and they spend part of their life cycle in water.

### Step 3: Evolution of Reptiles
- Amphibians eventually gave rise to reptiles. Reptiles are primarily terrestrial and have adaptations such as lungs for breathing air and skin that is more resistant to water loss compared to amphibians.

### Step 4: Evolution of Mammals
- Finally, mammals evolved from a group of reptiles known as synapsids. Mammals are characterized by features such as hair or fur and mammary glands for nursing their young.

### Summary of the Sequence
The correct sequence in the evolution of mammals is:
1. Fish
2. Amphibians
3. Reptiles
4. Mammals