Computer Graphics World

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e d i t i o n 3 , 2 0 1 8 | c g w 5 1 D uring the Early Juras- sic, 195 million years ago, in what is now known as Antarctica, there existed a landmass still tenuously connected to Africa, Madagascar, Australia, and India. The climate was warm and lush. Dinosaurs, both carnivores and herbivores, shared this large area in the typical daily quest for survival. Over millions of years, the Antarctic continent gradu- ally shied south, riding on its crustal plate. The animals that roamed this land represent a handful of lineages that survived the massive end-Permian ex- tinction event 252 million years ago, the most severe of its kind in Earth's history. How do we know that dino- saurs once ruled the Antarc- tic? Several early geological ex- peditions noticed fossil bones in Antarctic rocks. In 1990, Dr. William Hammer of Augustana College (Rock Island, Illinois) and his team discovered Juras- sic dinosaur specimens from a fossil bone bed high in the central Transantarctic Moun- tains at almost 13,000 feet (4,000 meters). At that altitude, gasoline- powered rock-cutting equip- ment doesn't work too well, but the group managed to extract a number of specimens from the encasing mudstone, including parts of the crested theropod Cryolophosaurus and the more fragmentary remains of another dinosaur, the herbivore Glacial- isaurus. These became part of Chicago's The Field Museum collections and later led to the active involvement of the museum's curator of dinosaurs, Peter Makovicky, in the hunt for Antarctic Mesozoic vertebrates. Subsequent expeditions in 2003 and 2010 recovered more materials of Cryolophosaurus and Glacialisaurus, as well as partial skeletons of two new species of herbivorous dinosaur. BRAIN SCAN The materials of Cryolopho- saurus and Glacialisaurus came from a jumble of bones washed into the site by ancient flooding events, and represent parts of at least three skeletons. One of the elements found was the partial skull of a Cryolophosaurs elliotti, which was unique among dinosaurs in its possession of a flaring bony crest running across the tops of the skull above the eye sockets. The uniqueness of this skull and its excellent preservation suggested that a model of its brain (a virtual endocast) could be generated from scans of the skull. However, early attempts using a medical CT scanner were inconclusive, as medical CT scanners are tuned for humans and lack the energy to penetrate the dense encapsu- lating rock. Several years later, Dr. Martin Jones at Ford Motor Co., using its more powerful industrial CT scanner, was able to generate useful images of the skull with excellent contrast between the rock and fossil bone. The museum group (which included Makovicky and Arthur Andersen, president of Virtual Surfaces, specializing in 3D scanning and digital editing) received the CT scan data and proceeded to create a 3D model of the brain and associated anatomical struc- tures, such as the inner ear canal, and neural and vascular pathways. Unfortunately, the anterior part of the brain case floor was not ossified, so the full shape of the brain was not preserved. To generate a more complete brain model, they scaled and modeled the anterior section of a T. rex brain endocast, which had been 3D scanned several years prior. Additional scans were also produced by Varex Imaging of Franklin Park, Illinois, for the new, as yet unnamed dinosaurs, to capture their anatomy and develop mounted replicate skeletons and digital interactives for The Field Museum's exhibit "Antarctic Dinosaurs," which opened in June 2018. Besides actual fossils, mount- ed skeletal casts, and fleshed- out models of prehistoric animals from Antarctica's past, visitors can experience equip- ment used by the first polar ex- peditions as well as present-day scientists in Antarctica. Touch- able reproductions of bones and interactive touch-screen media generated from the scans of Cryolophosaurus and other Antarctic fossils are featured throughout the exhibit, and a media-rich environment brings visitors up close and personal with the excavating of fossils in one of the most remote spots on the planet. Arthur Andersen is president of Virtual Surfaces, Inc., and Dr. Peter Makovicky is curator of dinosaurs, Section of Earth Sciences, at The Field Museum in Chicago. HEAD CASE 3D SCANNING PRODUCES A VIRTUAL MODEL OF A UNIQUE DINOSAUR'S BRAIN AND MORE BY ARTHUR ANDERSEN AND DR. PETER MAKOVICKY

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