Huayanglong is the earliest complete stegosaur skeleton discovered in the world. Its discovery provides empirical evidence for the theory that stegosaurs originated in East Asia, but the status of Huayanglong in the origin of stegosaurs still needs to be verified.
During the Middle Jurassic period, the banks of some rivers were often covered with small ferns, like a green carpet. This was a paradise for Huayangosaurus, as the small ferns were perfectly suited to its grinding teeth and were very palatable. However, while they enjoyed their meal, they often became a tempting prey for predators such as Qisaurus. Therefore, they lived in small groups for defense. A group typically consisted of 3-5 Huayangosaurus, led by a male, with the other members usually being adult females and juveniles. The young Huayangosaurus stayed close to their parents, as the adults possessed weapons to deal with their formidable predators, deterring any malicious attackers from launching a direct attack.
So, what kind of "defensive" weapons did the adult Huayangosaurus possess? It turns out that these small creatures, which walked on short, thick limbs, were actually among the earliest stegosaurs in history. During their evolution, they developed a unique set of defensive weapons along their backs, from neck to mid-tail: two long, symmetrical rows of triangular bony plates, an extra spine on each shoulder, and four sharp, spike-like ridges nearly 40 centimeters long at the end of their tail. Such armor is terrifying enough to inspire fear just by looking at it.
When a hungry Qilong attempts to attack a Huayanglong, the Huayanglong will adjust its body position, pointing its long bony plates at the attacker. The color of the bony plates quickly turns a bright red due to blood engorgement; this is not only the Huayanglong's most severe physical warning but also a stance only adopted in times of crisis. At the same time, it will shake its shoulders, making the large spikes on its shoulders even more conspicuous; and vigorously swing its tail, letting the four prominent spike-like ridges sway back and forth in front of the Qilong. Simultaneously, it will seize the opportunity to fiercely lash out at its predator with its tail, or forcefully stomp the ground with its limbs and sweep the ground with its tail, sending water and plant debris from puddles into the air.
While these defensive measures weren't powerful enough to kill large invaders, the sheer force of the formation was enough to confuse their predators who dared to attack: how could these normally timid creatures suddenly become so terrifying? Usually, unless they were starving, these invaders would stop attacking to avoid injury and instead seek out easier prey.
Although stegosaurs likely appeared as early as the Early Jurassic, paleontologists' focus on their origin and evolution actually began with the discovery of the Huayangosaurus at Dashanpu, Zigong, Sichuan, China. In 1980, the first Huayangosaurus skull fossil was discovered in China. Since then, paleontologists have discovered more fossilized bones. A total of 12 Huayangosaurus individuals have been excavated at Dashanpu, with two complete skeletons displayed at the Zigong Dinosaur Museum and the Chongqing Natural History Museum, respectively.
Chinese name: Huayanglong
Latin name: Huayangosaurus
Age of existence: Middle Jurassic
Fossil origin: Sichuan, China
Physical characteristics: 4.3 meters in length
Diet: Plants
Species: Stegosaurus
Meaning: Dedicated to the ancient Huayang Kingdom
