Description and Classification

Bolong was a medium-sized herbivorous dinosaur, reaching an estimated length of about 4 meters (13 feet) and weighing several hundred kilograms. Like other iguanodontians, it was likely primarily bipedal, meaning it walked on its two hind legs, but it could also have moved on all fours when foraging for food. Bolong had a horny beak at the front of its mouth for cropping plants, and rows of teeth further back in its jaws for grinding tough vegetation.

Bolong is classified as an early member of the Hadrosauroidea, the group that includes the well-known “duck-billed” dinosaurs such as Edmontosaurus and Parasaurolophus. It is considered a basal (early or primitive) hadrosauroid, meaning it shows some features of later, more advanced hadrosaurs, but also retains some characteristics of more primitive iguanodontians like Iguanodon. It is thought to be closely related to other early hadrosauroids from Asia, such as Jinzhousaurus and Equijubus.

Distinguishing Features

Bolong possessed several unique anatomical features that help paleontologists distinguish it from other dinosaurs. These include:

• A distinct, rounded bump or boss on the jugal bone, which is part of the cheek.
• A relatively short gap (diastema) between its beak and the first tooth in the lower jaw.
• A generally slender build compared to some of its ornithopod relatives.
• Five sacral vertebrae (vertebrae fused to the pelvis), which is typical for early hadrosauroids.

Paleoenvironment and Diet

Bolong lived in what is now the Yixian Formation in China. During the Early Cretaceous, this area was a dynamic environment with forests, lakes, and active volcanoes. The climate was likely temperate with distinct seasons. Bolong shared this rich ecosystem with a diverse range of other life forms, including other herbivorous dinosaurs like the horned Psittacosaurus, feathered theropods such as Sinosauropteryx and Caudipteryx, various sauropods, early birds, mammals, fish, and insects.

As a herbivore, Bolong‘s diet would have consisted of plants available in its environment. It likely fed on low-growing vegetation such as ferns, cycads, and early flowering plants, using its beak to snip off plant parts and its cheek teeth to process them.

Significance and Ongoing Research

The discovery of Bolong is important because it provides valuable information about the early evolution and diversification of hadrosauroid dinosaurs. Its mix of primitive and more advanced features helps scientists understand the evolutionary steps that led from earlier iguanodontians to the highly successful hadrosaurids of the Late Cretaceous. Bolong adds to the incredible fossil diversity found in the Yixian Formation, offering a clearer picture of the animal life in this ancient ecosystem.

Ongoing research continues to focus on refining Bolong‘s exact position within the ornithopod family tree. Comparative studies with other early hadrosauroids and iguanodontians help to clarify the evolutionary relationships and patterns of diversification among these plant-eating dinosaurs. Each new fossil discovery from regions like Liaoning contributes to our understanding of dinosaur evolution during the Cretaceous period.