Description and Classification

Amurosaurus was a type of “duck-billed” dinosaur, recognized by its broad, flat snout that resembled a duck’s bill. It was an herbivore, meaning it only ate plants. Scientists believe Amurosaurus could walk on both two legs (bipedal) and four legs (quadrupedal). It likely ran on two legs to escape danger and walked or grazed on all fours. It is estimated to have been about 6 to 8 meters (20 to 26 feet) long and may have weighed around 2 to 3 metric tons. Like other members of its group, the lambeosaurines, Amurosaurus likely had a hollow, bony crest on its head. While a complete adult crest has not yet been found, fossils from younger Amurosaurus individuals show the beginnings of one. These crests were probably used for display, perhaps to attract mates or identify each other, or possibly to make sounds, much like those seen in related dinosaurs such as Parasaurolophus and Corythosaurus.

Amurosaurus belongs to the family Hadrosauridae, often called the duck-billed dinosaurs. Within this large family, it is classified in the subfamily Lambeosaurinae, which includes all hadrosaurs that had hollow head crests. Its closest relatives are thought to include other Asian lambeosaurines like Sahaliyania and Olorotitan. It also shares some features with lambeosaurines found in North America, such as Lambeosaurus. The study of Amurosaurus helps scientists understand how these crested dinosaurs moved and spread across different continents millions of years ago.

Distinguishing Features

Amurosaurus had several features that made it unique when compared to other hadrosaurs:

• The specific shape and connections of its skull bones, particularly those around the eye socket and snout, were different from other lambeosaurines.
• It had a long hip bone (ilium) with a distinctive and somewhat slender outline.
• Though not fully known in adults, its hollow head crest, which is a key characteristic of lambeosaurines, would have been a major feature distinguishing it from non-crested hadrosaurs like Edmontosaurus.
• Some of its forearm bones (the ulna and radius) had unique shapes and characteristics not seen in closely related species.
• Compared to some other large hadrosaurs, Amurosaurus seems to have had a relatively lighter and more slender build.

Paleoenvironment and Diet

Amurosaurus lived in a region that, during the Late Cretaceous, was a floodplain environment with many rivers, lakes, and forests. The climate was likely temperate, meaning it had warm summers and cool winters, with changing seasons. Fossils of Amurosaurus have often been found in “bone beds,” which are large areas where many skeletons are preserved together. This suggests that Amurosaurus may have lived in herds. These groups might have died together during natural events like floods or droughts. Living in herds could have offered protection from predators and helped in finding food.

As an herbivore, Amurosaurus ate plants. Its mouth was well-equipped for this diet, containing hundreds of closely packed teeth that formed “dental batteries.” These strong tooth structures were perfect for grinding up tough plant material such as conifer needles, ferns, and early types of flowering plants that grew in its forest and riverside habitat. Other dinosaurs found in the same rock layers as Amurosaurus include another type of hadrosaur called Kerberosaurus, the armored dinosaur Arkharavia, and large meat-eating tyrannosaurid theropods, which may have been predators of Amurosaurus.

Significance and Ongoing Research

Amurosaurus is a very important dinosaur because it was one of the last non-avian dinosaurs to live before the massive extinction event that wiped out most dinosaurs around 66 million years ago. Its discovery provides valuable information about the kinds of dinosaurs that lived in Asia, especially in cooler, high-latitude regions, just before this major extinction. Studying Amurosaurus helps scientists understand how different dinosaur groups, like the lambeosaurines, evolved and spread across the ancient world, showing connections between dinosaur populations in Asia and North America.

The bone beds where Amurosaurus fossils are found also give important clues about its social behavior, strongly suggesting it lived in groups. Ongoing research continues to explore the anatomy of Amurosaurus. Scientists are particularly interested in finding more complete adult skulls to fully understand the shape and size of its head crest. Researchers are also working to determine its exact place in the hadrosaur family tree and to learn more about the ecosystem it inhabited. Future discoveries may reveal more details about its growth from a juvenile to an adult and its interactions with other species in its environment, including other hadrosaurs like Kerberosaurus that shared its habitat.