The high water level contributed to the spread of extensive shallow seas from the beginning of the Jurassic period. Ancient marine inhabitants spread across the expanses of Europe and Asia, North America, Africa, and many other places.

Red and green algae, with enviable stability, formed the basis of marine ecosystems. The diversity of marine landscapes was diluted by elegant sea lilies, for example, Liliocrinus, and bright and quirky sea sponges, such as Sphenaulax and Peronidella. The Jurassic became the time of the formation of powerful coral reefs, composed mainly of six-rayed corals (Hexacorallia).

Various invertebrates filled the seas, among which ammonites were particularly noticeable, becoming one of the most numerous groups of animals. The first true Belemnitinae appear - squid-like cephalopod mollusks, with an internal shell resembling a tiny projectile.

Fish development continues. The first rays appear. Some fish reach quite impressive sizes. For example, the filter...