page_title: Edmontosaurus
section_title: Postcranial skeleton
hierarchical_section_title: Edmontosaurus / Description / Postcranial skeleton
caption_attribution_description: English: Original figure caption: Reconstruction of Edmontosaurus regalis mainly based on CMN 2288, CMN 2289, CMN 8399, and UALVP 53722 (modified from Campione and Evans [8]). Deutsch: Rekonstruktion von Edmontosaurus regalis, hauptsächlich basierend auf den Fossilexemplaren CMN 2288, CMN 2289, CMN 8399, und UALVP 53722 (verändert aus Campione und Evans [8]).
context_page_description: Edmontosaurus is a genus of hadrosaurid dinosaur. It contains two known species: Edmontosaurus regalis and Edmontosaurus annectens. Fossils of E. regalis have been found in rocks of western North America that date from the late Campanian stage of the Cretaceous Period 73 million years ago, while those of E. annectens were found in the same geographic region but in rocks dated to the end of the Maastrichtian stage of the Cretaceous, 66 million years ago. Edmontosaurus was one of the last non-avian dinosaurs, and lived alongside dinosaurs like Triceratops, Tyrannosaurus, Albertosaurus and Pachycephalosaurus shortly before the Cretaceous–Paleogene extinction event.
  Edmontosaurus included some of the largest hadrosaurid species, measuring up to 12 metres long and weighing around 4.0 metric tons. Evidence does exist in the form of two fossilized specimens housed at the Museum of the Rockies for an even greater maximum size of 15 m and weighing 9.07 metric tons for Edmontosaurus annectens. Several well-preserved specimens are known that include not only bones, but in some cases extensive skin impressions and possible gut contents.
context_section_description: The number of vertebrae differs between specimens.  E. regalis had thirteen neck vertebrae, eighteen back vertebrae, nine hip vertebrae, and an unknown number of tail vertebrae.  A specimen once identified as belonging to Anatosaurus edmontoni (now considered to be the same as E. regalis) is reported as having an additional back vertebra and 85 tail vertebrae, with an undisclosed amount of restoration. Other hadrosaurids are only reported as having 50 to 70 tail vertebrae, so this appears to have been an overestimate. The anterior back was curved toward the ground, with the neck flexed upward and the rest of the back and tail held horizontally. Most of the back and tail were lined by ossified tendons arranged in a latticework along the neural spines of the vertebrae. This condition has been described as making the back and at least part of the tail "ramrod" straight. The ossified tendons are interpreted as having strengthened the vertebral column against gravitational stress, incurred through being a large animal with a horizontal vertebral column otherwise supported mostly by the hind legs and hips.
   
  The shoulder blades were long flat blade-like bones, held roughly parallel to the vertebral column. The hips were composed of three elements each: an elongate ilium above the articulation with the leg, an ischium below and behind with a long thin rod, and a pubis in front that flared into a plate-like structure. The structure of the hip hindered the animal from standing with its back erect, because in such a position the thigh bone would have pushed against the joint of the ilium and pubis, instead of pushing only against the solid ilium.  The nine fused hip vertebrae provided support for the hip.
  The fore legs were shorter and less heavily built than the hind legs. The upper arm had a large deltopectoral crest for muscle attachment, while the ulna and radius were slim. The upper arm and forearm were similar in length. The wrist was simple, with only two small bones. Each hand had four fingers, with no thumb (first finger). The index second, third, and fourth fingers were approximately the same length and were united in life within a fleshy covering. Although the second and third finger had hoof-like unguals, these bones were also within the skin and not apparent from the outside. The little finger diverged from the other three and was much shorter. The thigh bone was robust and straight, with a prominent flange about halfway down the posterior side. This ridge was for the attachment of powerful muscles attached to the hips and tail that pulled the thighs (and thus the hind legs) backward and helped maintain the use of the tail as a balancing organ.  Each foot had three toes, with no big toe or little toe. The toes had hoof-like tips.
caption: Reconstruction of E. regalis
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