Description and Classification

Lambeosaurus was a large plant-eating dinosaur. It could walk on two legs (bipedal) or four legs (quadrupedal), likely moving on all fours while feeding and then rearing up on its hind legs to run or reach higher vegetation. Adult Lambeosaurus could reach lengths of about 9 to 10 meters (30 to 33 feet) and weigh several tons. Like other hadrosaurs, it had a broad, flattened snout resembling a duck’s bill, which was toothless at the front but contained hundreds of tightly packed cheek teeth further back. These teeth formed “dental batteries” that were excellent for grinding tough plant material.

The most remarkable feature of Lambeosaurus was its cranial crest. This hollow structure was formed by an expansion of the nasal bones and premaxillae and was connected to the nasal passages. The shape and size of the crest varied among different species of Lambeosaurus and also likely changed as the animal grew or differed between males and females. For example, the crest of Lambeosaurus lambei is often described as hatchet-shaped or mitten-shaped, with a forward-pointing projection and a larger, rearward-pointing spine. Another species, Lambeosaurus magnicristatus, had a much larger, more rounded, and fan-shaped crest.

Lambeosaurus belongs to the family Hadrosauridae, a diverse group of ornithopod dinosaurs. Within this family, it is a member of the subfamily Lambeosaurinae, which is characterized by prominent, hollow cranial crests. Other well-known lambeosaurines include Corythosaurus, Parasaurolophus, and Hypacrosaurus. These dinosaurs shared many similarities in body plan but differed significantly in the shape and structure of their crests.

Distinguishing Features

Lambeosaurus can be distinguished by several key features:

• A prominent, hollow cranial crest on its skull. The shape varied, but common forms include hatchet-like crests with a forward spike and a rearward projection (L. lambei), or very large, rounded crests (L. magnicristatus).
• A “duck-bill” snout, typical of hadrosaurs, used for cropping vegetation.
• Complex dental batteries in its cheeks, designed for efficient grinding of plants.
• A bipedal and quadrupedal stance, allowing it to move in different ways.

The purpose of the crest is a subject of much scientific discussion. Theories suggest it could have been used for species recognition, as a visual display to attract mates or intimidate rivals, or to produce sounds for communication by acting as a resonance chamber. It might have also helped with the sense of smell or even temperature regulation, though these ideas have less support.

Paleoenvironment and Diet

Lambeosaurus lived in what is now North America during the Campanian stage of the Late Cretaceous. The environment at that time was a coastal plain with rivers, swamps, and forests, featuring a warm, humid climate. This ecosystem, particularly in areas like the Dinosaur Park Formation in Alberta, was rich in plant life, providing ample food for large herbivores like Lambeosaurus.

As a herbivore, Lambeosaurus fed on a variety of plants. Its dental batteries were well-suited for grinding tough vegetation, such as conifers, ferns, cycads, and early flowering plants. It was likely a browser, feeding on plants at low to medium heights. Lambeosaurus shared its habitat with many other dinosaurs, including other hadrosaurs like Parasaurolophus and Corythosaurus, horned dinosaurs such as Centrosaurus and Styracosaurus, and predatory theropods like Gorgosaurus.

Significance and Ongoing Research

Lambeosaurus is a significant dinosaur because it provides valuable insights into the diversity and evolution of hadrosaurs, particularly the lambeosaurines with their elaborate crests. The well-preserved fossils, including multiple skulls and skeletons, have allowed paleontologists to study its anatomy in detail.

Ongoing research continues to focus on several aspects of Lambeosaurus biology. The function of its crest remains a key area of investigation, with studies using CT scans to reconstruct the internal nasal passages and computer modeling to explore potential sound production capabilities. Comparisons between different specimens, including juveniles and adults, help scientists understand how the crest developed throughout an individual’s life and whether there were significant differences between males and females (sexual dimorphism). The discovery of multiple species within the genus Lambeosaurus also prompts research into their evolutionary relationships and ecological separation. Lambeosaurus helps paint a clearer picture of the complex ecosystems of Late Cretaceous North America.