When did the trilobite, known as a living fossil, become extinct?

Trilobites are the most representative ancient animals that appeared in the Cambrian period, with a bright spine on the back, ventral surface and back of the body, and the abdomen is mainly a soft peritoneum and two rows of slender appendages. Structurally, the dorsal carapace of the trilobite is divided into three parts, the carapace, the cuirass, and the carapace, which receive the name of the trilobite like three leaves side by side. Trilobites have the most complex head carapace structure.

The middle raised part is the head saddle, the sides are balls, and the eyes are on the balls. The ball is penetrated by cotton threads, and the inner part between the two sides of the line is collectively called the cranium, and the two sides are called the movable ball or free ball. The middle part of the cotton thread passes between the snow and the snow leaves, allowing the trilobite to molt here, and the type of cotton thread is an important basis for the classification of the trilobite.

The cuirass consisted of multiple thoracic segments that were connected to each other and could move freely. Each thoracic segment has a pair of backs, which divides the thoracic segment into the first day of the festival and the two sides of both sides. Nail art is a whole plate formed by the fusion of several individual sections, the shape and size of which vary depending on the species.

There are always a variety of needles on the edges of the manicure. In general, the Cambrian occurrence was dominated by marine invertebrates and birds. In addition to trilobites, invertebrates include arthropods such as trilobites, protocassettes, brachiopods, mollusks, gastropods, bicorns, cephalopods, sea urchins, sea lilies, and sea flats belonging to arthropods.

The wooden pen pomegranate of the pen stone animal, there are solid insects in the protozoa, as well as the spinal cord animal summer eel, primitive vertebrate, Haikou fish, Kunming fish and so on. During the Cambrian period, there were no real terrestrial creatures, and the land was barren.

Over time, trilobites are evolving into new "technologies". For example, more than 400 million years ago during the Ordovician and Devonian periods, trilobites quickly evolved excellent swimming abilities due to the sudden increase in marine predators, and the thick spines on their bodies evolved to help them quickly escape when they encounter danger and resist enemy attacks. On the other hand, some trilobites flinch immediately when they encounter danger, evolving the ability to hide in the sand of the ocean floor.

However, trilobites appear to have become stronger at different times in evolution, but the researchers found that from the early Cambrian to the Permian period, no matter how the trilobites evolved, there didn't seem to be much change in the head. What the hell is going on? Why do trilobites keep repeating the "hairstyle" left by their ancestors?

Trilobites became extinct 100 million years ago, and due to the global cooling climate, about 100 families of organisms became extinct.

The bug is more than 200 million years old, and it became extinct about 100 million years ago, during the Permian period.

Hundreds of millions of years ago, it can be seen that a lot of time has passed now, and they are very powerful insects, but they still haven't adapted to the environment.