Floodplains are extensive plains located along rivers. On these territories, the river can overflow during floods. In river valleys, after the change in the river's course, parts of the channel with standing water - old channels or oxbow lakes - may remain. Some of such old channels turn into independent lakes or swamps. Sometimes, part of the soil along the riverbanks also becomes marshy. For this reason, the animal and plant life of the floodplain, lakes, and swamps can strongly echo each other and even have common elements.

The main feature of floodplains is their ability to retain a large amount of moisture. In addition, the waterlogged soils are very fertile. This creates favorable conditions for the growth of vegetation and the existence of a wide variety of animals.

In the first half of the Cretaceous period, horsetails, ferns, clubmosses, and mosses, such as Marchantites, grew abundantly in river valleys. However, flowering plants such as Leefructus played an increasingly...