Fake lizard? A look at the "illegitimate child" of the Triassic ancient sea

In the middle Triassic period, when dinosaurs were just beginning to strut on land, the oceans were also occupied by reptiles, and Nothosaurus was the most common type in the western Tethys Ocean.

Restoration of Zhang's Noxosaurus preying on a small Swelllophosaurus

Nothosaurus belongs to the order Nothosaurus, and its fossils are often found in the stratigraphic layers where Guizhousaurus was found. The first Nothosaurus fossil found in my country was an incomplete specimen accidentally discovered by Mr. Yang Zhongjian, the namer of Hu's Guizhousaurus, in 1965 when he was studying other specimens. Therefore, it was named Accidental Xingyisaurus and was classified as a member of the family Platyrhinidae. In subsequent studies, it was found to have the characteristics of Nothosaurus, so the original species name was abolished and it was treated as an undetermined species of the genus Nothosaurus.

In addition to the abolished species name, the name of the magic dragon itself is also quite surprising. Although it sounds full of middle school feeling, like a summoned beast or a big boss in a fantasy work, the real meaning of this scientific name is "fake lizard". In Greek, it also means "illegitimate child", so it has been translated as "bastard dragon". The reason may be that their appearance and behavior are a mixture of characteristics of many other animals.

They look somewhat similar to crocodiles, with a slender body, a small and flat skull, short limbs, a flat tail, but a very long neck.

The sizes of different species of Nothosaurus vary greatly. The smallest one is only a few dozen centimeters, similar to the Guizhousaurus of the swollen-ribbed dinosaur family, and the largest one can reach 6 meters.

Apart from the shortened front segment of their limbs, simplified elbow joints, slightly increased number of phalanges in some species, and webbed toes, their limbs do not show particularly strong adaptability to aquatic life in terms of structure. Their clawed feet indicate that they also have a certain ability to move on land, so they would rest on the shore and enter the water when hunting, similar to today's seals or sea lions.

Like Guizhousaurus, they do not have the ability to live in the ocean and can only hunt in shallow sea areas near the continental margin. When they swim, they use their long and powerful tails to propel their bodies forward. Although their thicker soles are more conducive to supporting the body on land, they are also very helpful for turning when chasing prey.

Most of the prey that needs to be hunted by chasing are fish. The long and sharp teeth of the Nothosaurus are like nails in the upper and lower jaws. They can not only pierce the body of these slippery prey, but also close up to form a cage, trapping the prey in the mouth and making it unable to escape. In addition to chasing, Nothosaurus has another set of fishing skills, which is to use its long and muscular neck. When the fish swims in front of them, they quickly turn their heads and bite it.

Such teeth and hunting methods make them professional fishermen, but in fact, other small or young marine reptiles are also on their menu. Scientists have found the remains of Placodontosaur preserved in the stomach of the fossil of Osaurus (a Nothosaur less than 2 meters long).

When they finish hunting, they will spend most of their time on land, but not too far from the seaside. This way they can enjoy the sunshine and avoid being hunted by other large marine reptiles such as ichthyosaurs. When they encounter threats from land, they can also quickly return to the sea.

During the large-scale sea retreat at the end of the Triassic period, Nothodonts became extinct along with other reptiles living in shallow seas due to the change from shallow seas to deep seas and a sharp decrease in food sources. However, the large number of fossils left behind by these once prosperous animals provide important evidence for studying the faunal relationships and geological changes at that time.