The Edmontosaurus mummy SMF R 4036, nicknamed the Senckenberg mummy or Edmond, is a well-preserved dinosaur fossil in the collection of the Senckenberg Museum (SMF) in Frankfurt am Main, Germany. It was found in 1910 in Wyoming, United States, in rocks of the Lance Formation that date to the late Maastrichtian, close to the Cretaceous–Paleogene extinction event around 66million years ago. The mummy is ascribed to the species Edmontosaurus annectens (originally Trachodon), a member of the Hadrosauridae ("duck-billed dinosaurs"). It comprises a nearly complete skeleton that was found wrapped in skin impressions, a rare case of preservation for which the term dinosaur mummy has been used. The fingers of the right hand are wrapped in a mitten-like envelope of skin impressions, initially interpreted as a paddle unsuited for terrestrial locomotion, thereby reinforcing the now outdated hypothesis that hadrosaurs were aquatic. The impression of a horny beak is also preserved with this specimen. Plant remains found in the body cavity were interpreted as stomach contents, suggesting a diet of terrestrial plants. It is now believed that this plant material was washed into the body cavity of the carcass.
It is assumed that the individual died during a drought, in or near a riverbed. Subsequently, the carcass would have dried out before being carried away by a sudden flood and been buried rapidly. Sand filled the body cavity, preserving the three-dimensional shape of the body, and a biofilm (bacterial mat) on the skin formed a thin crust of clay that preserved the shape of the skin in positive relief (protruding up from the surface). The mummy was found by fossil hunter Charles H. Sternberg and his sons, who sold their numerous finds to museums in North America and Europe. It is one of the best preserved hadrosaurid mummies and the second to be discovered, after the first such mummy was discovered by the Sternbergs in the same region two years earlier.
Discovery and research history
The mummy was discovered in early September1910 by the Sternbergs, a family of commercial fossil hunters consisting of Charles H. Sternberg and his three sons George, Charles, and Levi in rocks of the Lance Formation in Converse County (today Niobrara County), Wyoming, United States. 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 (AMNH) in New York City. In 1908 and 1909, they had also found two skulls of the horned dinosaur Triceratops, one of which was sold to the Natural History Museum, London, while the other was bought by the AMNH. In 1910, preceding the discovery of the mummy, the party had excavated an Edmontosaurus skeleton and four Triceratops skulls, two of which were acquired by the Senckenberg Museum.
The Senckenberg mummy comes from the southern Schneider Creek (today spelled Snyder Creek), on the Zerbst Ranch. Charles M. Sternberg, who had so far been unsuccessful in finding specimens that season, discovered a (hip) vertebra and a hind limb weathering out of grey sandstone as he roamed the area in search of fossils with his brother Levi. The party moved its camp to the site on 4 September and was joined by the local Lon Galbreath. Their equipment consisted of four horses, a heavy lumber wagon, and a buggy. The recovery of the fossil was the most elaborate the family had ever undertaken. Charles H. Sternberg was determined to secure every fragment of the skin impressions, which is why the blocks packed for transport were particularly large: the block containing the mummy's trunk weighed over , while the entire fossil weighed about . Since the Sternbergs had no pulley, the block was lifted step by step, by elevating it using levers of poplar wood and subsequently shoveling sand underneath. When the block was lifted to a height of , it could be loaded onto a wagon for transportation to the railway station away in Edgemont, South Dakota. The excavation and transport took two and a half months to complete.
Charles H. Sternberg offered to sell the fossil to , paleontologist and head of the paleontology department of the Senckenberg Museum (, SMF) in Frankfurt, Germany. Drevermann was able to pay the required sum of US$2,500 () through a donation from the industrialist Arthur Weinberg. Shortly after Drevermann's commitment, Sternberg received an offer from the Canadian Museum of Nature in Ottawa. The museum offered twice the amount of money for the fossil than Sternberg was to receive from the Senckenberg Museum. Sternberg wrote in 1917:
The mummy arrived at the Senckenberg museum in 1911. At that time, the preparators were still occupied with one of the Triceratops skulls that the museum had received from Sternberg the previous year, so that the preparation of the mummy began only in 1912. Preparation was completed in 1920, probably being delayed by World WarI. The mummy was among the first larger fossils to be prepared using compressed-air tools, a technique developed from 1914 onwards by Christian Strunz, the museum's preparator-in-chief. Several German-language publications on the mummy were published in the early 1920s, focusing on supposed stomach contents, the anatomy of the skull, and the movements of the jaws during chewing.
During World War II, a construction of sandbags was built around the mummy to prevent damage from bombing raids. When the bombings intensified, the mummy was moved to a safer location outside the city. On the way back to the museum after the war, however, the mummy fell off a truck and burst into multiple pieces; the subsequent restoration took more than 10 years. From 1963–1964, a new cellar was built to house the mummy, allowing it to be viewed from both the sides and from the room above. Since the initial 1920s studies, little research had been done on the specimen until the museum initiated the "Edmontosaurus project" in 2018. This project included the excavation of about 30 tonnes of a bonebed in the vicinity of the original excavation site of the mummy. The excavated blocks, containing hundreds of bones of Edmontosaurus and other animals, were shipped to Frankfurt and prepared as part of the museum's exhibition. Further research on the mummy itself was also initiated, leading to a re-evaluation of the supposed stomach contents and a paleoenvironmental reconstruction based on pollen from the body cavity. The mummy, dubbed "Edmond" by the museum, is one of the museum's most valuable fossils.
Significance and classification
The Senckenberg specimen was the second dinosaur mummy to be discovered. The term dinosaur mummy was originally coined by Henry Fairfield Osborn in 1911 for the Edmontosaurus mummy of the AMNH. 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. A third mummy was discovered by Barnum Brown in 1912 in Alberta, Canada, and subsequently described as the new genus Corythosaurus. Yet another mummy was discovered by Sternberg in 1916, which he sent to London during World WarI. The transport ship, the , was sunk by a German raider ship in December 1916, resulting in the loss of this mummy as well as many other fossils discovered by Sternberg. Additional mummies have been excavated since the turn of the millennium, such as a Brachylophosaurus mummy nicknamed "Leonardo" and an Edmontosaurus mummy nicknamed "Dakota".
The mummy belongs to the species Edmontosaurus annectens within Hadrosauridae, a family of ornithischian () dinosaurs. It was initially assigned to the genus Trachodon, which encompassed nearly all known hadrosaurid specimens at that time. Osborn initially assigned the specimen to the species Trachodon annectens. In a 1942 monograph on North American hadrosaurs, Richard Lull and Nelda E. Wright moved the species together with the mummy into the new genus Anatosaurus, as Anatosaurus annectens. In 1990, Michael K. Brett-Surman and Ralph Chapman proposed that the species actually belongs within the genus Edmontosaurus, which was followed by subsequent reviews. The majority of dinosaur skin impressions are referable to hadrosaurids. In North American specimens from the Maastrichtian age, skin impressions are 31 times more abundant in association with hadrosaurid specimens than with any other coeval group. The reasons for this distribution are unclear. Of all known hadrosaurid skin impressions, 25% belong to Edmontosaurus.
Description
The skeleton is mostly complete but lacks one of the two hind limbs and the end of the tail; it is more complete than the AMNH mummy. The skull is completely preserved, including the impression of the horny beak and the scleral ring around the pupil of the eye. Sternberg reported that the trunk and skull together were long, the tail was long, and the rib cage was wide. The skull is long. The individual was about 122% the size of the AMNH mummy, and was probably an old adult.
The bones of the mummy are fully (still in their original anatomical position) and mostly preserved three-dimensionally, not flattened as with many other fossils. The forelimbs are oriented backwards and upwards, and the skull is elevated relative to the trunk. The preserved hind limb has its fibula (calf bone) and tibia (shin bone) folded against the femur (thigh bone), while the foot is pointing downwards. Preserved skin impressions come from the right side of the trunk and the neck as well as both forearms. Especially well-preserved skin is found around the right hand. The palm of this hand shows polygonal scales about in diameter, while those of the upper surface of the hand are twice this size. Most other skin impressions have been separated from the skeleton during preparation.
Paleobiology Supposed aquatic lifestyle and posture
The fingers of both the AMNH and Senckenberg mummies are completely enclosed in a mitten-like envelope of skin impressions. Osborn, in 1912, interpreted the impressions of the AMNH mummy as interdigital webbing and the forelimb as a long paddle, indicating an aquatic lifestyle for hadrosaurids. The idea of an aquatic lifestyle had been proposed before, but it was only after the discovery of the two mummies that this idea became the universally accepted doctrine. According to Lull and Wright, the paddle-like limb of the Senckenberg mummy confirmed that these animals were aquatic, and the lack of foot pads or hooves showed that the forelimbs were unsuited for walking. In his 1911 account on the discovery of the Senckenberg mummy, Charles Hazelius Sternberg speculated that trachodons "[...] lived in the water, and only came on the land at the peril of their lives, as they had no means of defense against the king of carnivorous reptiles, Tyrannosaurus [...]".
In 1964, John H. Ostrom argued 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 of an aquatic lifestyle was finally abandoned after Robert Bakker, in 1986, argued that the skin between the fingers of the AMNH mummy was actually the remnant of a fleshy pad enveloping the hand that had dried out and flattened during mummification. Furthermore, Bakker argued that the fingers were short and could hardly have been spread apart, which distinguishes them fundamentally from the long, spread toes of today's paddling animals such as ducks.