Readers are likely aware that the Hadrosaurus Benjamin Waterhouse Hawkins created for the Academy of Natural Sciences was the first mounted dinosaur skeleton. It is less widely known, however, that this Hadrosaurus was a plaster facsimile, which included none of the actual fossils that inspired it. (edit: not quite, see comments). The title of first dinosaur mount composed of original fossils belongs to the Belgian Iguanodon assembled by Louis Dollo in 1891 (I should probably write about this eventually, but Fernanda Castano has an excellent account at Letters From Gondwana). So what was the first real fossil dinosaur mount on this side of the Atlantic? Glad you asked – that would be none other than the 1901 Edmontosaurus at the Peabody Museum of Natural History.
The PMNH Edmontosaurus with Deinonychus and Centrosaurus. Photo by the author.
There are plenty of Edmontosaurus skeletons on display today, but the Yale mount is noteworthy because of its remarkably modern appearance. While the Hawkins Hadrosaurus and Dollo Iguanodon were upright tail-draggers, the Edmontosaurus could be mistaken for a mount constructed in the last quarter century. Its raised tail, horizontal posture, and energetic gait all reflect current thinking about dinosaur posture and locomotion. And yet, it was built at the turn of the century, back when paleontologists supposedly all thought of dinosaurs as lethargic lizards.
The Hawkins Hadrosarus and Dollo Iguanodon. Images from Paper Dinosaurs.
The scientist behind this mount was Charles Beecher. Born in Pennsylvania, Beecher studied at the University of Michigan before taking an Assistant of Paleontology position at Yale in 1888. He completed his PhD under Marsh, who apparently thought highly of him (and Marsh didn’t think highly of many people). Although his preferred research subjects were Paleozoic invertebrates, Beecher could be counted on to help prepare his mentor’s vast collection of dinosaur fossils, when needed. When Marsh died in 1899, Beecher succeeded him as the head of the Peabody Museum, and set himself the task of mounting one of the institution’s best dinosaur specimens for display.
Beecher selected YPM VP 2182 as the Peabody Museum’s first fossil mount because it was nearly complete and mostly articulated. Known to Marsh and Beecher as “Claosaurus” annectens*, this Edmontosaurus skeleton was collected in Wyoming by John Bell Hatcher (because of course it was). Beecher and assisting preparator Hugh Gibb attempted to preserve the fossils within their original matrix as much as possible. Since the specimen was somewhat laterally compressed, Beecher kept the right side mostly in situ and built up the left in high relief. The head and neck were technically never removed from their matrix block, but since the head was found curved under the body it had to be rotated into its life position. All told, only the right ribs, the corocoids, the final two-thirds of the tail, and some of the vertebral processes were reconstructed. No attempt was made to restore the ossified dorsal tendons, which were poorly preserved on this specimen.
Beecher’s Edmontosaurus, ca. 1917. Source
The complete mount is 13 feet tall and 29 feet long, its tail extending past the edge of the 27 foot slab. For a few years, it was the largest fossil mount ever built. The slab itself is made up of original matrix blocks sealed together with a manufactured surface created from plaster, resin, and ground Laramie Formation sandstone. It was assembled in four pieces secured to wooden frames. These were designed to be separated and moved with relative ease, although PMNH staff have yet to try.
According to Beecher, he imbued the Edmontosaurus with its lively pose in order to preserve the in situ orientation of the pelvis and left femur. It is worth quoting Beecher’s 1901 description of the mount in full:
“It is intended that this huge specimen should convey to the observer the impression of the rapid rush of a Mesozoic brute. The head is thrown up and turned outward. The jaws are slightly separated. The forearms are balancing the sway of the shoulders. The left hind leg is at the end of the forward stride and bears the entire weight of the animal. The right foot has completed a step and has just left the ground preparatory to the forward swing. The ponderous and powerful tail is lifted free and doubly curved so as to balance the weight and compensate for the swaying of the body and legs. The whole expression is one of action and the spectator with little effort may endow this creature with many of its living attributes.”
Much like the AMNH Gorgosaurus, the Yale Edmontosaurus demonstrates that early 20th century paleontologists’ supposed aversion to energetic and agile dinosaurs has been grossly overstated. Beecher saw Edmontosaurus as a powerful, active animal, and actually criticized the earlier reconstructions by Hawkins and Dollo. He correctly pointed out that the back-swept ischia of ornithopod dinosaurs would not allow room for the drooping tails they had reconstructed, and also noted that fossilized dinosaur trackways never show the mark of a dragging tail.
Edmontosaurus as presently displayed in the Great Hall of Dinosaurs. Source
Beecher died suddenly in January of 1904, and the Edmontosaurus display ended up being one of his final professional accomplishments. Despite the relative dearth of dinosaur material available at the time, Beecher’s careful and impartial study of the available evidence allowed him to reconstruct this animal in a way that is still considered accurate 114 years later. Beecher’s work shows us that old research isn’t necessarily outmoded. Good science can come from any age and any source, if one only takes the time to look.
*Today, the genus Claosaurus is reserved for Claosaurus agilis from Kansas. The referred species annectens has since been placed in Thespesius, Trachodon, Anatosaurus, and now Edmontosaurus.
References
Beecher, C.E. 1901. The reconstruction of a Cretaceous dinosaur, Claosaurus annectens Marsh. Transactions of the Connecticut Academy of Arts and Sciences. Vol. 11, pp. 311-324.
Jackson, R.T. 1904. Charles Emerson Beecher. The American Naturalist. Vol 38, No. 450.
Marsh, Othniel C. 1892. Restorations of Claosaurus and Ceratosaurus. American Journal of Science. Vol. 44, pp. 343-349.
EXTINCT MONSTERS 
