Edmontosaurus mummy SMF R 4036
The Edmontosaurus mummy SMF R 4036, also known as the Senckenberg mummy or Edmond, is a remarkably well-preserved dinosaur fossil in the Senckenberg Museum in Frankfurt, Germany. It was found in September 1910 in Wyoming, USA, in rocks from the Lance Formation dating to the late Cretaceous period, around the time of the dinosaur–extinction event about 66 million years ago. The specimen belongs to Edmontosaurus annectens (once called Trachodon) and is a duck‑billed hadrosaur. What makes it special is that almost the whole skeleton is there, still wrapped in skin impressions, so the body’s shape is preserved three‑dimensionally.
The right hand is especially well preserved, with the fingers enclosed in a mitten‑like layer of skin impressions. The skull shows a beak, which is also preserved, and the animal’s overall posture is more life‑like than in many other fossils. For a long time, scientists thought the preserved plant material in the body cavity was the dinosaur’s stomach contents, suggesting a diet of terrestrial plants. Today, most researchers think that material was washed into the carcass after death.
How the animal died and was preserved is still debated, but many scientists now think the Edmontosaurus died during a drought near a river. The body dried out, was swept into a fast‑moving flood, and then quickly buried in sand. A biofilm of microorganisms on the skin helped form a thin clay crust that kept the skin’s shape after it decayed. Because of this process, the mummy is sometimes described as a “skin rendering” or “mask,” rather than a true skin impression.
The mummy was discovered by the Sternberg family of fossil hunters—Charles Hazelius Sternberg and his three sons—who carefully recovered it. They transported a massive block weighing about 1,400 kilograms (3,000 pounds) containing the trunk. The whole fossil weighed around 4,500 kilograms (10,000 pounds). The specimen arrived at the Senckenberg Museum in 1911, and preparation began in 1912, finishing in 1920, helped by the museum’s use of compressed‑air tools.
Over the years, the Senckenberg mummy has been a focal point of study and public display. In the 2018 “Edmontosaurus project,” researchers excavated a nearby bonebed, bringing hundreds of Edmontosaurus bones to Frankfurt for study and exhibition. This work prompted a re‑examination of the mummy itself and a rethinking of its supposed stomach contents and the environment in which it lived.
In 2025, paleontologists proposed that SMF R 4036 and other Lance Formation mummies come from animals that died beside a river during droughts and were buried quickly by floods. They described the skin around the body as a clay‑lined mask rather than preserved skin, noting that several other Edmontosaurus mummies and a few other dinosaurs were found in a roughly 10‑kilometer area they call the “mummy zone.” The Senckenberg mummy is the northernmost and oldest piece in that zone.
Details about the fossil include that the skeleton is nearly complete, with the skull intact and a trunk about 3.7 meters long and a tail about 1.7 meters long. The animal was probably an old adult and larger than the famous American Museum of Natural History mummy. The body’s skin, especially around the right side of the trunk and neck and on the forearms, is preserved, and the beak impression is visible. The discovery and study of Edmond have helped scientists understand Edmontosaurus anatomy, feeding, and how such fossils can form under exceptional, rapid burial conditions. The site also offers clues about the ancient forested, warm, and humid environment of the Lance Formation, with plant material and pollen pointing to a rich ecosystem near water.
This page was last edited on 3 February 2026, at 03:01 (CET).