The Making of a Dinosaur

A Firsthand Account by Michael Anderson

 

Peabody Museum Preparator Michael Anderson checking a one-third scale fiberglass cast of the Torosaurus skull for accuracy.

 

The Peabody brought together paleontologists, zoologists and an army of artists and volunteers [under the direction of Dr. Jacques Gautier and the sculptor, Michael Anderson] to create a 21-foot life-size bronze sculpture of Torosaurus

 

In December 1999, then Yale Peabody Museum Director Richard Burger and Vertebrate Paleontology Curator Jacques Gauthier approached me about creating a life-sized dinosaur sculpture for the front of the Museum. Dr. Gauthier wanted a very accurate model for presentation, so he sent me to work with Ralph Chapman at the National Museum of Natural History at the Smithsonian Institution. Using animated computer models, and with advice from specialists worldwide, Chapman had recently created the most accurate skeletal reconstruction of Triceratops to date.

The Skeleton

 

Marsh’s 1896 reconstruction of Triceratops prorsus.

 

A complete skeleton of Torosaurus has never been found. Because Triceratops and Torosaurus have very similar postcranial (from the neck down) skeletons, Chapman suggested using the more widely available Triceratops bones for the reconstruction. The reconstruction is based on the few skulls that are known, together with specimens of the closely related Triceratops.

Illustration taken from The Dinosaurs of North America, by O.C. Marsh, 1896. Sixteenth Annual Report of the U.S. Geological Survey, Washington, D.C. Plate LXXI. Courtesy of the Yale Peabody Museum Archives

The Skeleton

 

The contours of the fossil skull were recreated using foam board.

 

To ensure the accuracy of the sculpture, I produced midsaggital and transverse contours of the skull. These were placed over the full-scale clay skull to create the correct contours.

The Skeleton

 

The one-third scale model in progress.

 

Each bone was sculpted at one-third scale. The bones were articulated and accurately posed for the Yale Peabody Museum sculpture. Chapman and his team worked for several hours to adjust the skeletal anatomy to their liking.

The Muscles

 

Anderson’s notations on a Chinese laboratory manual’s diagram of the musculature of an alligator.

 

Once the skeleton was created and approved, the muscles had to be added. To insure accuracy, at each stage the sculpture was approved by Professor Gauthier, whose laboratory at Yale is involved in cutting-edge research on dinosaur musculature anatomy. Dr. Gauthier introduced me to his then graduate student, Dr. Takanobu Tsuihiji, who dissects extant animals with evolutionary relationships to dinosaurs. I spent hours researching his anatomy texts of iguanas, alligators and birds, reviewing the various muscles and their functions, and assisting him in actual dissections, which helped me to literally “flesh out” the sculpture. I also reviewed the scientific literature to find paleontological sources on how muscles attach to bones.

The Muscles

 

The one-third scale model in progress.

 

This research informed the sculpting of the muscles over the bones. The one-third scale model was built up through the application of muscle over the skeletal structure.

Detail of a cast of fossilized Chasmosaurus skin impressions.
YPM-PU catalog no. 12871

 

The final step was to texture and apply the skin. Using a cast of a rare fossilized impression of Chasmosaurus skin, along with studying reptilian scutellation (scale) patterns with Dr. Gauthier and Taka Tsuihiji, I produced an educated guess of what the skin patterns for the Torosaurus could have looked like. By this painstaking method of building the muscles over the skeleton and then adding the skin layer, the most accurate sculpture of Torosaurus to date has been created.

The Skin

 

Each scale was painstakingly placed and shaped by hand.

 

The scales started as balls of plasteline clay, each individually pressed and smoothed onto the sculpture. Altogether over a ton of clay was used on the full-scale clay prototype.

The Skin

 

Assistant sculptor Mike Ferrara marking out the skin patterns.

 

Rather than using rigid measurements, the artists marked areas of the full-scale clay sculpture with guides made from string to ensure that the skin patterns graded regularly in width across the animal’s body.

Credits and Acknowledgements

 

Scientific accuracy was of the utmost importance to me in every phase of this project and my
final sculpture benefited greatly from my discussions with the following paleontologists:

David Baier—Brown University
Dr. Michael Brett-Surman—Smithsonian Institution
Daniel Brinkman—Yale Peabody Museum
Ralph Chapman—Idaho State University (formerly of the Smithsonian Institution)
Dr. Peter Dodson—University of Pennsylvania
Andrew Farke—Stony Brook University
Dr. Stephen Gatesy—Brown University
Dr. Alan Gishlick—formerly of the National Center for Science Education, Inc.
Dr. Jacques Gauthier—Yale Peabody Museum
Dr. John Hutchinson—Royal Veterinary College Structure and Motion Lab (formerly of Stanford University)
Steve Jabo—National Museum of Natural History, Smithsonian Institution
Dr. Walter Joyce—Yale Peabody Museum
Peter Kroehler—National Museum of Natural History, Smithsonian Institution
Dr. Scott Sampson—University of Utah
Dr. Takanobu Tsuihiji—Field Museum of Natural History (formerly of Yale University)

Their knowledge of the scientific literature, vertebrate anatomy and functional morphology were indispensable to me as I sculpted the Yale Peabody Museum’s Torosaurus.—Michael Anderson