Hadrosaurs were a family of dinosaurs that are commonly called “duck-billed” dinosaurs. Can you guess why? Yes, it’s because they often had flat, wide mouths that looked like a duck’s bill! These large animals lived during the Late Cretaceous Period, right up until the extinction of all non-bird dinosaurs. They grew quite large, ate plants, and sometimes had striking crests on their heads, the purpose of which is still debated by paleontologists.
Hadrosaurs were members of a group of dinosaurs called Ornithopods. The Hadrosaurs were the last of these dinosaurs, which first appeared during the mid-Jurassic period as small, two-legged creatures before eventually growing into the duck-billed giants of the Cretaceous. As these dinosaurs grew accustomed to grazing on the ground, their bodies evolved to be more suited to this style of feeding. They became more reliant on their front legs to walk (though they could still stand on two legs as well), and their backbones curved toward the ground, giving them a humped appearance like a bison.
One popular dinosaur that served as something of a link between the smaller, two-legged Ornithopods and the larger Hadrosaurs was Iguanodon, of the Early Cretaceous Period. It lived around 125 million years ago. Iguanodon was one of the earliest dinosaurs ever discovered, though it was originally described by Gideon Mantell as a fully four-legged creature with a prominent spike on its nose. Later specimen discoveries would reveal that this nose horn was actually the animal’s thumb, and that its front legs were much smaller than previously thought.
Later, Hadrosaurs would become some of the most common and successful dinosaurs of their time, with a number of different and varied types. Many had striking head crests. Some, like Edmontosaurus, had a fleshy crest, like the comb of a rooster. Since soft tissue such as this is rarely preserved, it is not known if every Edmontosaurus had such a crest, or if it was only present in members of a certain species, or perhaps only found on males or females.
Other Hadrosaurs, like Parasaurolophus, had large elaborate crests of bone. These crests were hollow, and their exact purpose is still unknown, though scientists do have some theories. Many paleontologists believe it served to amplify the sounds made by the dinosaur so they could be heard over long distances. Others believe it was for display, to attract mates. It could also have been a sign of maturity, as skulls of smaller, younger dinosaurs feature shorter crests. Once It was even proposed that Parasaurolophus could mix chemicals in its hollow crest that would allow it to breathe fire through its nostrils, like a dragon, though this theory was not based on any scientific evidence and was widely discredited.
Not every Hadrosaur had a crest. Some, like Gryposaurus, had prominent nose humps at the front of their heads, instead of crests at the rear. Gryposaurus is one of the few dinosaurs that have been found with skin impressions, allowing scientists to better understand more how these dinosaurs looked while alive. Gryposaurus is known to have had a row of trapezoid-shaped spikes running down its back. Edmontosaurus is another Hadrosaur that has left behind well-preserved remains, including fossilized “mummies” that include not only skin, but muscle tissue as well.
Despite their duck-like bills, Hadrosaurs likely behaved much more like cows than waterfowl. It’s believed to have spent their days grazing lazily on plants. They likely traveled in large herds to better protect them from predators like the Tyrannosaurids Albertosaurus, Gorgosaurus, Daspletosaurus and Tyrannosaurus Rex. Fossilized tracks found in Alaska show thousands of footprints made by a large Hadrosaur herd. Seeing such a large group of these impressive dinosaurs on the move must have been quite a sight!
Check out the following products for more Duck-billed Dinosaur fun:
Dinos TOOB - with mini Iguanodon figure
Dino Babies TOOB - with mini Parasaurolophus Baby figure
Sue & Her Friends TOOB - with mini Iguanodon figure
Dinosaur Skulls TOOB - with Parasaurolophus skull