We modeled the brain structure of Tyrannosaurus rex by CT scanning a fossilized braincase (AMNH FR 5117) from the collection of the American Museum of Natural History. We segmented the brain cavity and associated internal structures using Avizo, yielding what’s known as a brain endocast. We then cleaned up the model in Maya, tweaked and branded it in Zbrush, and then uploaded it to Sketchfab. Ryan Ridgely did the 3D visualization work, and Witmer and Ridgely published a scientific article on tyrannosaur brain evolution, including this specimen, in 2009 (http://bit.ly/1R8xyHE). An OBJ file can be downloaded here and, if necessary, converted to an STL for 3D printing. Not for commercial use.