page_title: Edmontosaurus mummy SMF R 4036
section_title: Possible stomach contents
hierarchical_section_title: Edmontosaurus mummy SMF R 4036 / Paleobiology / Possible stomach contents
caption_attribution_description: English: The Edmontosaurus mummy SMF R 4036 on display at the Senckenberg Museum, Frankfurt, Germany.
context_page_description: The Edmontosaurus mummy SMF R 4036 is an exceptionally well-preserved dinosaur fossil in the collection of the Naturmuseum Senckenberg in Frankfurt am Main, Germany. Found in 1910 in Wyoming, United States, it is ascribed to the species Edmontosaurus annectens, a member of the Hadrosauridae. 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. Notably, the horny beak is preserved with this specimen. Plant remains found within the thorax cavity had been interpreted as stomach contents, although later research questioned this identification. 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. SMF R 4036 is one of the four best preserved hadrosaurid mummies, and was the second to be discovered. The find was made by fossil hunter Charles Hazelius Sternberg and his sons, who sold their numerous finds to various museums in North America and Europe.
context_section_description: Following the preparation of the mummy in Frankfurt, German paleobotanist Richard Kräusel studied an earthy mass of plant remains found within the thoracic cavity of the mummy, which he considered probable stomach contents based on their composition and location. 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. Kräusel presented his findings in 1921 at the annual meeting of the "Paläontologische Gesellschaft" in Frankfurt, the German paleontological society, where they where questioned immediately, probably due to the prevalent belief that hadrosaurids fed on aquatic instead of terrestrial plants, given their assumed aquatic lifestyle. 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. Drevermann, defending Kräusels hypothesis, argued that the remains had been found on the pubis bone of the mummy, where they could have fallen when the carcass was lying on its right side. Kräusel's presentation was, together with the subsequent discussions, published as short notes in the society's journal in 1922.
  During the following century, the supposed stomach contents were often regarded as one of the best available evidence for the diet of Edmontosaurus and hadrosaurids in general, although the credibility of this evidence was repeatedly questioned. Although Sternberg had reported stomach contents from the AMNH mummy, these have never been studied. Ostrom, in his 1964 paper, 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. Later, different authors noted that since the mass was removed from the mummy and macerated, it would be no longer available for research, and that Kräusel's hypothesis can no longer be validated.
  German paleontologist Dieter Uhl, in 2020, analyzed the available historic accounts, microscope slides of plant remains prepared by Kräusel, and additional plant remains found within the sandstone that surrounded the mummy, concluding that the presumed stomach or gut contents are probably external in origin. According to Uhl, the plant fragments described by Kräusel are much smaller than other known hadrosaurid gut contents and coprolites, and instead compare well with the plant remains extracted from the surrounding rock that were transported by water. Furthermore, the mass described by Kräusel was found atop of the prepubis of the hip and therefore in the upper region of the body cavity, which is an unlikely location for stomach or gut contents as the animal was found laying on its underside. Uhl hypothesized that the mass of plant remains could have formed after most of the body cavity had already been filled with sand by the action of a river, leaving a chamber that acted as a sediment trap where the fine plant detritus suspended in the water accumulated.
caption: Skull in front view, showing the beak
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