Is it a dinosaur or a fish? Although it is not a pond creature, it will never become a dragon.

Among prehistoric marine animals, ichthyosaurs are a type of star creature that many people are familiar with. Its Latin name Ichthyosaurus and its appearance both indicate that it is a fish-like reptile. Ichthy refers to fish and saurus means lizard. However, there is another type of creature that is just the opposite of them. Its Latin name is Saurichthys, which means lizard-like fish. This is the dragon fish.

Dragon fish is not a precious fish species that we raise nowadays. The modern dragon fish is a trade name, generally referring to the bony tongue fish of the subclass of neopterygoid fish. The dragon fish mentioned here is a type of fish of the order of ray-finned fish that became extinct in the late Triassic period. It is named because its skeleton has the characteristics of fish and reptiles. Their body is shaped like a torpedo, the tail fin is a normal tail, the anal fin is symmetrical with the dorsal fin and is far away from the pectoral fin. Such characteristics indicate that they are good swimmers who can swim at high speed in the water and prey on other fish.

Modern Dragon Fish

However, dragon fish are not suitable for chasing prey in open waters because of the size of their pectoral fins. The pectoral fins of fish play a role in propulsion, balance and guidance, which can prevent the propulsion force generated by the tail fin and gravity from causing the body to dive down. The larger the pectoral fins, the more it can avoid the danger of accelerated sinking, which is why fish with extremely fast swimming speeds usually have huge pectoral fins. However, the pectoral fins of dragon fish are pitifully small, which means that despite having a body that can swim at high speeds, the pectoral fins can only play a small role in balance and guidance.

Therefore, when facing prey, the dragon fish will never boast, "If I catch you, I will kill you", and can only ambush. In this case, the dragon fish has the advantage, because ambush requires concealment, and algae or rock cracks are excellent choices. Their torpedo-shaped body can avoid getting stuck or injuring the fins when sprinting. In addition, there is also a hypothesis that the dragon fish has mottled stripes or lines on its body to confuse prey. Although this hypothesis is reasonable, there is currently no fossil evidence to support it.

Dragon fish fossil

After locking onto its prey, the dragonfish will slowly adjust its posture to approach the prey. When the distance is sufficient, it will swing its tail fin at a high speed in a short period of time to catch the prey off guard, and bite it with its long snout, which is nearly one-third of its body length. The fossil specimens found in Italy even retain undigested remains of P. pterosaurus, but this is not conclusive evidence that the dragonfish hunted the pterosaur. Perhaps it was just sitting back and enjoying the fruits of its labor. In either case, it provides an interesting perspective for the ecological study of the dragonfish.

Restoration of the spiny dragon fish

Dragon fish once escaped the Permian extinction event and seized the opportunity to occupy the middle and upper ecological niches before the ocean was dominated by large reptiles. Among the more than 40 species discovered so far, the largest can reach more than 1 meter and the smallest is only a few dozen centimeters. The fossils are distributed in all continents of the world except South America and Antarctica. In recent years, dragon fish fossils discovered in the same location in Yunnan, Guizhou and other places have shown that there are multiple different genera, showing diverse ecological adaptability.

Dragon fish eventually died out in the mass extinction event at the end of the Triassic period, but as witnesses of the recovery of the marine ecosystem after the end-Permian mass extinction event, their surviving fossils provide us with important clues for studying the marine environment at that time.