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Facts, images, & animations for Allosaurus feeding story
Dinosaur: Allosaurus
Family: Theropoda, Allosauridae
Time period: late Jurassic, about 150 million years ago
Discovery: The Allosaurus specimen used in this study was found in 1991 near
Shell, Wyoming. It was excavated by the Museum of the Rockies (MOR),
University of Wyoming Geological Museum, and the U.S. Bureau of Land
Management. It’s currently housed in the Museum of the Rockies and bears
the catalog number MOR 693.
The fossil: The skeleton is an almost complete subadult Allosaurus, missing only
the tail. It has been nicknamed “Big Al” and has been studied extensively for
its healed injuries and feeding adaptations.
Allosaurus (“Big Al”) at a glance:
Age: not quite adult, 80% grown
Weight: 1.6–2 tons (2.5 tons as an adult)
Length: 25 feet (30 feet as an adult)
Skull length 2.3 feet
Major points:
a. A newly applied engineering method called multibody dynamics (originally
developed for robotics) allows scientists to test how Allosaurus would have
fed based on different ideas on muscle sizes and attachments.
b. Allosaurus could move its head especially fast from side-to-side to strike its
prey.
c. Unique muscle arrangements in Allosaurus enabled it to drive its teeth
downward into flesh as it pulled back (retracted) its head.
d. Despite being over 20-feet long and twice as heavy as a polar bear,
Allosaurus fed like the American kestrel and other small falcons: driving the
head downwards to grip prey and then yanking back and up with its neck
and body.
Lead author: Eric Snively, PhD. Ohio University, Russ College of Engineering,
Athens, Ohio, USA. es180210@ohio.edu Phone: 740-591-8928
Secondary author: Lawrence Witmer, PhD. Ohio University Heritage College of
Osteopathic Medicine Athens, Ohio, USA. witmerL@ohio.edu Phone: 740-
591-7712
For downloadable graphics and animation, visit:
http://www.oucom.ohiou.edu/dbms-witmer/allosaurus_mechanics.htm

Images and animations
(Note: Images are compressed for this document. Click the links to download larger files)
A modern-day kestrel (a small falcon) is perched atop the skull of the Jurassic predatory dinosaur
Allosaurus. A key finding of the new study is that Allosaurus had a feeding style similar to falcons. In
both cases, tearing flesh from carcasses involved grasping meat with the jaws and tugging back and up
with the neck and body. Courtesy of WitmerLab at Ohio University.
Download 300-dpi JPG: http://www.oucom.ohiou.edu/dbmswitmer/images/Allosaurus_kestrel_WitmerLab.jpg

Skeleton and soft tissues of the head and neck of the late Jurassic predatory dinosaur Allosaurus.
Courtesy of WitmerLab at Ohio University.
Download 300-dpi JPG: http://www.oucom.ohiou.edu/dbmswitmer/images/Allosaurus_PE_WitmerLab_still_03.jpg

Skeleton and soft tissues of the head and neck of the late Jurassic predatory dinosaur Allosaurus.
Courtesy of WitmerLab at Ohio University.
Download 300-dpi JPG:
White background: http://www.oucom.ohiou.edu/dbmswitmer/images/Allosaurus_PE_WitmerLab_still_01.jpg
Black background: http://www.oucom.ohiou.edu/dbmswitmer/images/Allosaurus_PE_WitmerLab_still_02.jpg

Silhouettes of Allosaurus and a modern-day falcon with a similar feeding style, along with a human for
scale. Courtesy of WitmerLab at Ohio University.
Download 300-dpi JPG: http://www.oucom.ohiou.edu/dbmswitmer/images/Allosaurus_kestrel_silhouettes.jpg
Authors of the article with the replica of "Big Al," the subadult specimen (MOR 693) of Allosaurus used
in the study. Humans from left: Eric Snively, John Cotton, Ryan Ridgely, Lawrence Witmer. Courtesy of
WitmerLab at Ohio University.
Download 300-dpi JPG: http://www.oucom.ohiou.edu/dbms-witmer/images/Team_Allosaurus_2012-
12-18_working_DSC_0263.jpg

Animation of the feeding movements of the head and neck of the Jurassic predatory theropod dinosaur
Allosaurus based on multibody dynamics and soft-tissue reconstruction. Research supported by the NSFfunded
Visible Interactive Dinosaur project. Courtesy of WitmerLab at Ohio University.
• YouTube version: http://www.youtube.com/watch?v=tdezagMXE2w
• Download 1080 x 1080 (36 MB) 2:34 QuickTime movie: http://www.oucom.ohiou.edu/dbmswitmer/Movies/Allosaurus_feeding_WitmerLab_1080x1080.mov
• Download 720 x 720 (36 MB) 2:34 QuickTime movie: http://www.oucom.ohiou.edu/dbmswitmer/Movies/Allosaurus_feeding_WitmerLab_720x720.mov

The "Big Al" Quarry in 1991. Excavation of the Allosaurus skeleton (MOR 693) used in this study. See
http://bit.ly/YYsfS8 for more info on the specimen. The skull is at upper right. Courtesy of the Bureau of
Land Management Wyoming and the Museum of the Rockies.
Download a JPG: http://www.oucom.ohiou.edu/dbms-witmer/images/Allosaurus_BigAl_field_R1-
06741-0002.jpg

Mounted complete skeleton of "Big Al," the specimen of Allosaurus used in this study. See
http://bit.ly/YYsfS8 for more info on the specimen. Courtesy of the Bureau of Land Management
Wyoming and University of Wyoming Geological Museum.
Download a JPG: http://www.oucom.ohiou.edu/dbms-witmer/images/Allosaurus_BigAl_mount_R1-
06741-0005.jpg