Tetragonosaurus Facts
| Diet | Herbivore |
| Height | 2m |
| Length | 6m |
| Weight | 1.5 tonnes |
| Speed | 25 km/h |
| Environment | Land |
| Era | Cretaceous |
| Period | Late Cretaceous |
| Type | Ornithopod |
| Location | North America |

| Diet | Herbivore |
| Height | 2m |
| Length | 6m |
| Weight | 1.5 tonnes |
| Speed | 25 km/h |
| Environment | Land |
| Era | Cretaceous |
| Period | Late Cretaceous |
| Type | Ornithopod |
| Location | North America |
Tetragonosaurus was originally described as a distinct genus of ornithopod dinosaur from the Late Cretaceous period, approximately 83.6 million years ago. However, modern scientific analysis has revealed that the fossils attributed to Tetragonosaurus actually represent juvenile specimens of Lambeosaurus, a well-known crested duck-billed dinosaur from western North America.
When first discovered in Alberta, Canada, these fossils appeared different enough from adult Lambeosaurus specimens to warrant their own genus classification. The name 'Tetragonosaurus' meaning 'four-angled lizard' was given due to the distinctive shape of certain skull elements. These ornithopod dinosaurs would have been plant-eaters, using their sophisticated dental batteries to grind tough vegetation.
As juvenile Lambeosaurus, these dinosaurs would have grown into magnificent crested ornithopods, developing the characteristic hollow head crest that adult Lambeosaurus are famous for. The young animals likely lived in herds alongside their parents, learning to navigate the lush coastal plains and river deltas of Late Cretaceous North America.
This reclassification demonstrates how our understanding of dinosaur growth and development has advanced significantly since the early days of palaeontology, when juvenile and adult specimens of the same species were often mistaken for entirely different animals.
As juvenile Lambeosaurus, Tetragonosaurus specimens showed the characteristic duck-like bill of ornithopod dinosaurs but lacked the prominent hollow crest of adults. The skull elements displayed a distinctive four-angled shape that initially led scientists to classify them as a separate genus.
As young ornithopods, these dinosaurs likely stayed close to adult herds for protection and learning. They would have been capable of both bipedal and quadrupedal locomotion, switching between gaits as needed for feeding or escaping predators.
Tetragonosaurus was first described by Lawrence M. Lambe in 1914. The original fossils were discovered at Alberta, Canada.