Since Reddy named the hadrosaur in 1858, this last dinosaur quickly became a star, not only because of its massive body and peculiar beak, but also because it was widespread throughout North America before the end of the dinosaur era. As a result, numerous remains have been unearthed, often in remarkably well-preserved condition, including even its skin fossils. The most famous example is the hadrosaur mummy discovered by Sternberg in Kansas in 1908. When Sternberg found it, the poor creature was still in the same position it was in when it died over 70 million years ago, lying supine with its hind legs raised, clearly showing signs of painful convulsions before its death. Fortunately, the carcass was not damaged by scavengers, quickly dehydrated under the scorching sun, and miraculously preserved by being covered with fine sand. Had any step in this process been wrong, this treasure would never be before us.
Hadrosaurus was about 10 meters long and herbivorous. It had a relatively high skull and large eyes on either side of its face, similar to those of horses and cattle. Because these eyes could move upwards and it possessed relatively large optic nerves, Hadrosaurus had excellent eyesight, allowing it to remain highly vigilant against carnivorous dinosaurs. Its beak, formed by the extension and lateral expansion of the premaxilla and predentary bones, created a broad, duck-like snout, hence the name "hadrosaurus."
When discussing the characteristics of hadrosaurs, their name already tells us they had a flat, duck-like bill. This flat bill was densely packed with 2,000 rhomboid teeth (probably the dinosaur species with the most teeth discovered). Besides their astonishing number, these teeth had another distinctive feature: they were slanted and overlapping, with washboard-like abrasive surfaces; as old teeth wore down, new ones grew in to replace them. Furthermore, the hadrosaurs' upper and lower jaws could interlock their teeth, and combined with their well-developed joint system and strong muscles, they could freely move their jaws. Therefore, these teeth were able to cut and grind tough plant fibers into a paste, demonstrating that they were highly efficient feeding machines.
Compared to earlier herbivorous dinosaurs, this tooth arrangement improved the efficiency of grinding food. While plants adapted to the transition from the warm, humid Jurassic to the drier Cretaceous by altering their own structures, herbivorous dinosaurs evolved in response to changes in their diet. The advancements in food processing mechanisms by hadrosaurs enhanced their adaptability, making them one of the most successful herbivorous dinosaurs of the Cretaceous.
Chinese name: duckbill dinosaur
Latin name: Hadrosaurus
Age of existence: Late Cretaceous
Fossil origin: New Jersey, USA
Physical characteristics: 7-10 meters in length
Diet: Plants
Species: Ornithopods
Definition: A lizard with a beak like a duck's.
