Today’s post comes from Ravi Chandran and Tyler Keillor. Ravi Chandran is an ESCONI member and volunteer in Paul Sereno’s lab. Tyler Keiller is Manager of the fossil lab and past ESCONI member. He has presented at Paleofest and for ESCONI in the past. He is also paleo-artist.

The Fossil Lab in Washington Park (5437 S Wabash Avenue) holds an Open House each month on the second Thursday (April 9 – November 12) from 3:30-5pm.

Background:

Paul Sereno (https://paulsereno.uchicago.edu/) hardly needs an introduction: he grew up in Naperville and is a Professor of Organismal Biology and Anatomy at the University of Chicago. Paul has discovered several new dinosaur species on several continents, including at sites in Inner Mongolia, Argentina, Morocco and Niger. One of his most widely publicized discoveries is that of a nearly complete specimen of Sarcosuchus imperator – popularly known as SuperCroc – at Gadoufaoua in the Tenere desert of Niger. Paul has been featured on several TV documentaries on dinosaurs. In addition, he also uncovered a large Stone Age cemetery at Gobero in the Sahara, remnants of a people who lived from 10,000 to 5,000 years ago on the edge of what was then a large lake. A National Geographic documentary, Skeletons of the Sahara, was made about this discovery and premiered in 2013.

The Fossil Lab in Washington Park (5437 S Wabash Avenue) is a new 6,000 square foot facility that features fossil preparation space, multipurpose areas for community programs, and tons of specimens collected from Sereno’s worldwide expeditions, including the ones mentioned above.

CT Scanning Project:

SuperCroc: Discovered in 2000, the skull and jaws of Sarcosuchus imperator, an extinct dinosaur-eating croc that grew to 40 feet in length, are preserved in a block of hard sandstone. The size of the skull (5ft) and the density of the matrix makes it a challenge for CT scanning. Medical CT scanners do not have x-ray energies high enough to penetrate the fossil and cannot physically accommodate the size and weight.

Paul believes a high-resolution scan of the skull, especially the braincase can reveal many unknown anatomical details of the SuperCroc.

T-rex block: A rare Tyrannosaurus rex skeleton that Paul collected on a hilltop in Wyoming in 2001 is preserved in life pose, in a very dense and heavy (5,000 pound) block. A block from the belly of the beast with belly ribs was earlier sent to a CT scan facility in the Detroit area, but the results were disappointing. The x-ray energy was not high enough to penetrate the block and revealed little.

The images above show the T-rex and the belly block with ribs.

Fortunately, there is a high-energy industrial CT scanner facility in the Chicago region that is capable of such scans: at Varex Imaging in Franklin Park (https://www.vareximaging.com/franklin-park-location/). Varex graciously agreed to attempt scanning; and we decided to first perform two test scans: the snout end of the SuperCroc skull (already broken-off as shown above) and the belly block of the T-rex. If the test scans proved successful, we would then prepare the rest of the SuperCroc skull for the scan.

Test Scans:

In August 2024, we performed the two test scans at Varex, using their highest-energy (9Mev) x-ray system:

In the left image above, the x-ray source (linear accelerator) is the grey box on the right; the x-ray detector (flat panel) is the black rectangular box on the left, behind the turntable that holds the SuperCroc snout. The right
image above shows the snout on the turntable.

In medical CT scanners, the patient lies on a couch while the x-ray source and detector rotate around the patient. In industrial CT, the x-ray source and detector are stationary while the object rotates on a turntable. The energy of the x-ray source in the above scanner is approximately 100x more powerful than in medical CT scanners. In the scan facility above, a 6-foot thick concrete wall is needed to stop the x-ray beam!

The test scans proved successful:

Clockwise from top left above: 3-D visualization of the T-rex belly block showing the belly ribs; 3-D visualization of the snout; a slice through some of the teeth in the snout; Paul showing the images during a recent open-house at the Fossil Lab.

Next Steps:

Since the test scans were a success, we are now preparing the SuperCroc skull for the scan. The skull needs to be in a stable vertical position on the turntable for the scan. Due to the weight and size of the skull, this presents
another challenge: metallic supports (including screws and bolts) will cause distortions and artifacts in the x-ray images. Therefore, we are designing and building a support using only wooden braces and high-strength plaster. We will be happy to provide an update when the next stage of the scanning project is complete.