The Devonian period, which began about 419 million years ago and ended approximately 359 million years ago, was a time when diverse freshwater bodies formed on the territories of ancient islands and continents: rivers, lakes, and swamps. However, during this period, the root system of plants was just beginning to form, and there were no plants that would clearly define the banks, so rivers changed their course much more often.

The first trees - ferns (Archaeopteris) and club mosses (Leptophloeum) were not stable, their trunks and branches often ended up in bodies of water. In rivers, they blocked the water flow, creating natural dams. In addition, the wood began to rot, and under such conditions, the amount of oxygen in the water decreased significantly. These unusual conditions greatly influenced animals. Some fish, such as lobe-finned fish (Sarcopterygii), for example, Panderichthys and Tiktaalik, developed lungs to obtain additional oxygen from the air. In addition, they develope...