The origin and evolution of amphibians

The origin of amphibians probably occurred in the late Devonian period. At that time, a certain species of lobe-finned fish landed on land, creating a new direction of adaptation and evolution.

This was an adventure for early vertebrates, a bold step into a new environment that was completely foreign to them and to which they could only partially adapt. But once this progressive air-breathing fish took that step, it quickly transformed into a primitive amphibian. Since then, many new possibilities have been opened up for the evolutionary development of vertebrates.

Ichthyostega

Some scientists believe that what drives lobe-finned fishes to leave the water and land may be precisely the desire to get more water. This speculation holds that some lobe-finned fishes in the late Devonian period were likely to have been threatened by extreme drought, forcing them to try to find new pools or streams in order to continue to survive. This forced them to first Climbing onto dry land, some lobe-finned fishes found new water sources and were thus able to continue their fish lives; most explorers likely died miserably; however, the most successful were probably those on land. Individuals and their descendants who learned a new way of life have since created a new terrestrial living space, getting rid of the restrictions of water on vertebrates, laying the foundation for advancing in a more advanced evolutionary direction.

So far, the earliest vertebrate discovered by scientists is a primitive amphibian called "Ichthyostega".

The skull structure of Ichthyostega is solid, and the position and shape of the bones on the top cover are very similar to those of advanced lobe-finned fishes, but of course more advanced. The skeletal characteristics of the body of Ichthyostega show a wonderful combination of amphibians and fish. The backbone is slightly more advanced than that of lobe-finned fish, but the tail still retains fish-like fins. The strong shoulder straps, belt and associated fully developed front and rear limbs indicate that Ichthyostega could already move around on the ground on all fours.

Starting from the ancestor of Ichthyostega, amphibians (classes) have differentiated into three subclasses in the process of adapting to the terrestrial environment: Labyrinthia, Conospondyma, and Splenomegaly.

animal tags： amphibian Ichthyostega