After the Permian mass extinction, the Earth was reshuffled, and many "monsters" appeared in the sea...

The distinctive feature of the placodontosaurs are their millstone-shaped teeth, which include the shelled lycodontosaurs and the shellless placodontosaurs. Their fossils are mainly found in today's Central Europe and South my country.

The limbs of Placodontosaurus were not fully specialized, and it did not show the characteristics of being fully adapted to aquatic life. Scientists speculate that Placodontosaurus mainly lived in near-shore shallow sea areas. In the Triassic period, ichthyosaurs and nothodonts evolved into more ferocious predators, while Placodontosaurus was smaller in size and mainly ate mollusks. Therefore, compared with speed and flexibility, defense was more important to Placodontosaurus.

Placodontosaurs are generally fat, with short and thick legs and a bulky body. Except for the early members, most of them are covered with bony plates. Their appearance is similar to that of the current Testudinata. Many of their living habits are also similar to those of the Testudinata creatures, but the two have only evolved in parallel and there are still many obvious differences.

For example, most placodontosaurs have flat, thick, block-shaped teeth, which are convenient for crushing the shells of mollusks, while the teeth of living turtles have mostly degenerated and evolved into beaks; the skull of placodontosaurs has a pair of complete temporal fenestrae more than that of turtles; in addition, the head of placodontosaurs cannot be retracted into the shell, the tail is longer than that of living turtles, and the carapace structure is also different. The swimming method of placodontosaurs and turtles may also be different.

Although Placodon had tried its best to arm itself and protect itself, it still did not survive the fourth mass extinction event in the Triassic period. Scientists speculate that the cause of extinction may be related to its relatively single food source.