Reconstructing an Icon: Historical Significance of the Peabody’s Mounted Skeleton of Stegosaurus and the Changes Necessary to Make It Correct Anatomically by Ariel Revan

The iconic dinosaur Stegosaurus was named by Othniel Charles Marsh of Yale University in 1877 from several caudal elements and a large dermal plate of Stegosaurus armatus Yale Peabody Museum specimen 1850 found in the Late Jurassic Morrison Formation near Morrison, Colorado, USA (Marsh 1887). In 1910, the Yale Peabody Museum of Natural History was the first institution to construct a mounted composite skeleton of Stegosaurus, and there have been only two major changes to the mount in the last century (Lull 1910). The mount was originally intended to depict S. ungulatus (Marsh 1879), but because the validity of this species is subject to debate, and because the validity of the type species of the genus (S. armatus) has also been called into question, this classification is no longer informative (Galton, 2010). As part of the pending Great Hall Renovation project, the Yale Peabody Museum plans to remount its composite skeleton of Stegosaurus. The intention is to reconfigure the skeleton posed in a defensive posture swinging its tail at an attacking juvenile Allosaurus (Dingus 2011). My thesis focuses on ascertaining what details need to be adjusted in order to ensure the accuracy of the remounted stegosaur. Based on a thorough review of the literature and on measurements and observations made of specimens in museums in Denver, Switzerland, and here at Yale, I have determined that the following changes will be necessary to make the current mount correct anatomically when it is remounted in the renovated Great Hall: Replace the left femur with either Yale Peabody Museum specimen 1856 or 1858 and sculpt a matching right femur of similar size based on the left; Arrange the small anterior nuchal dermal plates in an alternating arrangement; Remove two pairs of anterior spikes from the tail; Add one cervical vertebra; Replace the current skull, a cast of United States National Museum specimen 4934, with a slightly larger skull sculpted from it.