page_title: Hadrosauridae
section_title: Anatomy
hierarchical_section_title: Hadrosauridae / Anatomy
caption_attribution_description: English: Photographer: en:User:Ballista Edmontosaurus skull, Oxford University Museum of Natural History.
context_page_description: Hadrosaurids, or duck-billed dinosaurs, are members of the ornithischian family Hadrosauridae. This group is known as the duck-billed dinosaurs for the flat duck-bill appearance of the bones in their snouts. The family, which includes ornithopods such as Edmontosaurus and Parasaurolophus, was a common group of herbivores during the Late Cretaceous Period in what is now Asia, Europe, Antarctica, South America, and North America. Hadrosaurids are descendants of the Upper Jurassic/Lower Cretaceous iguanodontian dinosaurs and had a similar body layout.
  Like other ornithischians, hadrosaurids had a predentary bone and a pubic bone which was positioned backwards in the pelvis. Hadrosauridae is divided into two principal subfamilies: the lambeosaurines, which had hollow cranial crests or tubes; and the saurolophines, identified as hadrosaurines in most pre-2010 works, which lacked hollow cranial crests. Saurolophines tended to be bulkier than lambeosaurines. Lambeosaurines included the aralosaurins, tsintaosaurins, lambeosaurins and parasaurolophins, while saurolophines included the brachylophosaurins, kritosaurins, saurolophins and edmontosaurins.
context_section_description: The most recognizable aspect of hadrosaur anatomy is the flattened and laterally stretched rostral bones, which gives the distinct duck-bill look, and some members of the hadrosaurs also had massive crests on their heads, probably for display. In some genera, including Edmontosaurus, the whole front of the skull was flat and broadened out to form a beak, which was ideal for clipping leaves and twigs from the forests of Asia, Europe and North America. However, the back of the mouth contained thousands of teeth suitable for grinding food before it was swallowed. This has been hypothesized to have been a crucial factor in the success of this group in the Cretaceous compared to the sauropods.
  Skin impressions of multiple hadrosaurs have been found. From these impressions, the hadrosaurs were determined to be scaled, and not feathered like some dinosaurs of other groups.
  Hadrosaurs, much like sauropods, are noted for having their manus united in a fleshy, often nail-less pad.
  The two major divisions of hadrosaurids are differentiated by their cranial ornamentation. While members of the Lambeosaurinae subfamily have hollow crests that differ depending on species, members of the Saurolophinae (Hadrosaurinae) subfamily have solid crests or none at all. Lambeosaurine crests had air chambers that may have produced a distinct sound and meant that their crests could have been used for both an audio and visual display.
caption: Edmontosaurus skull, Oxford University Museum of Natural History
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