The Edmontosaurus mummy SMF R 4036 is an exceptionally well-preserved dinosaur fossil in the collection of the Naturmuseum Senckenberg (SM) in Frankfurt am Main, Germany.

Found in 1910 in Wyoming, United States, it is ascribed to the species Edmontosaurus annectens (originally Trachodon), a member of the Hadrosauridae ("duckbilled dinosaur").

The fossil comprises a nearly complete skeleton that was found wrapped in impressions of its skin, a rare case of exceptional preservation for which the term "dinosaur mummy" has been used.

The mummy's hands are wrapped in skin impression, which was interpreted as evidence for interdigital webbing and an aquatic lifestyle in hadrosaurids; this hypothesis, although universally accepted once, is now widely refused.

The family had worked in this area since 1908, when they discovered the similar Edmontosaurus mummy AMNH 5060, which was acquired by the American Museum of Natural History in New York City.

[6]: 23  Charles Mortram, who had so far been unsuccessful in finding specimens that season, discovered the parts of the tail weathering out of the sandstone as he roamed the area in search for fossils with his brother Levi.

When the block was lifted to a height of 1.2 meters, it could be loaded onto a wagon for transportation to the railway station 75 miles (121 km) away in Edgemont, South Dakota.

[5][3][4] Charles Hazelius offered the fossil Fritz Drevermann [de], palaeontologist and head of the paleontology department of the Naturmuseum Senckenberg, for sale.

This term was later used to refer to a handful of similar hadrosaurid ("duck-billed dinosaurs") specimens with extensive skin impressions, all of which have been discovered in North America.

[1] The idea of an aquatic lifestyle had already been proposed in 1906 by Barnum Brown, who interpreted the great depth and flat sides of a hadrosaurid tail as evidence for its use in swimming.

[5]: 222  Doubts were not raised before 1964, when John H. Ostrom noted that hadrosaurids must have fed on resistant terrestrial plants rather than on soft aquatic ones, and that the skeleton was adapted for a bipedal locomotion on land.

The hypothesis was finally refuted by Robert Bakker in 1986, who argued that the skin between the fingers was actually the remnant of a fleshy pad enveloping the hand that had dried out and flattened during mummification.

This mass mostly comprised conifer needles (Cunninghamites elegans according to Kräusel), parts of tree branches, as well as seeds or fruits – these remains suggest a diet consisting of terrestrial plants.

In the discussions following the talk, Austrian paleontologist Othenio Abel argued that these remains could have simply been washed into the cadaver, a possibility that was considered unlikely by Kräusel, since pollen, fungi, or eggs of water insects, which he would have expected in a washed-in mass, are lacking.

Swedish paleontologist Carl Wiman argued that stomach contents do not necessarily reflect the diet, since food items could have been swallowed accidentally, as indicated by plant remains found in specimens of the modern platypus.

[21] Ostrom, in his 1964 paper,[18] cited the stomach contents of the Senckenberg mummy as further evidence for a diet consisting of terrestrial plants, questioning the aquatic lifestyle hypothesis which was universally accepted at the time.

[8] The mummy was surrounded by brownish, fine to medium sandstone, although sedimentological structures that might hint at the mode of preservation are not visible in surviving rock samples, and have not been recorded by the Sternbergs.

The body cavity of the mummy contained fossils such as plant remains, leaf impressions, and a fish, which may have been washed inside the carcass after the death of the animal.

[1][22]: 33–35  The Sternbergs noted that the preservation of the Senckenberg mummy differed: the skin did not adhere closely to the bone, but rather traced the original body contour.