Cretaceous Turtle Has Eggs in CT Scan

Michael Knell carried a 75-million-year-old turtle into Bozeman Deaconess hospital recently, then laid it carefully on the bed that slides into the CT scanner.

Hardly an ordinary patient, the turtle fossil was only the second in the world found with eggs inside it, said Knell, a Montana State University graduate student in earth sciences. His turtle (from the genus Adocus) came from the Grand Staircase-Escalante National Monument in Kanab, Utah. The previously described turtle, which was found in Alberta, is also an Adocus and lived about the same time. Knell wanted his fossil scanned to see if he could find a skull and more eggs and learn whether or not the eggs contained embryos.

"It allows us to peer inside without digging into it," Knell said. "It gives us a hands-off look without having to break anything."

"It's very cool," added Frankie Jackson, an MSU paleontologist who specializes in eggs.

The CT machine looks like a giant doughnut with a narrow bed attached. Patients normally lay on the bed, then ride through the scanner while it takes images of a particular area. In this case, Knell wanted to scan the entire turtle. Although the edges of its shell were missing, the fossil measured about one foot across and weighed 40 to 50 pounds.

[...]

Spence operated the scanner from an adjoining room while Knell and Jackson looked over her shoulders. As the CT scanner took cross-sections of the fossil, white images appeared -- slice by slice -- on Spence's computer screen.

"It's very, very dense," Spence said of the shell. "You can lose some detail when that happens. You have to penetrate enough to see, but you can sometime lose detail that way."

Jackson said CT scans generally work better on fossils than X-rays and MRIs do.

"Usually embryo bone doesn't show up too well on a CT scan, so we might no be able to see embryos very well, but it could clue you in that you need to look at the eggs a little closer," Jackson added.

As time went by, the scientists realized that the eggs weren't showing up as clearly as they'd expected and they'd need to examine the images more closely. As a result, Spence saved her images to a disc and gave it to Knell. He and Jackson said they would contact the Museum of the Rockies, which has special software for looking at CT images from a variety of angles. The researchers expect to present their findings during the fourth international Symposium on Dinosaur Eggs and Babies. Knell's adviser, David Varricchio, and Jackson are organizing the event, which will be held Aug. 8-10 at MSU.

sweet! Anyone have pix?