Dinosaur Egg - Research Techniques - X Rays

X Rays

X ray equipment and CAT scanners are the largest and most expensive equipment used to study fossil eggs. Both techniques rely on differences in density to see inside the eggs. The eggshell will vary from the rock formed out of the infilling sediment. X-ray images condense the whole interior of the egg into a 2D image. CAT scans, however, take slices in small regular increments that can be used to infer the 3D structure of the egg's interior.

X rays and CAT scans are typically used to look for embryo fossils within the egg. As of Carpenter's writing all alleged embryos discovered using this method were actually false alarms. These were generally caused by variations in the type of infilling mineral or cementation. Sometimes eggshell fragments in hatched eggs have been mistaken for embryo bones. Even when embryonic bones are known from an egg specimen they typically show up very poorly in X rays or CAT scans because the weaklyossified bones with be fossilized at basically the same density as the infilling sediment. The only truly reliable way to discover a dinosaur embryo is to cut the egg open or dissolve some of its eggshell away.

When CAT scans are used on baby dinosaur skulls the results are also mixed. Ken Carpenter observed a CAT scan of one baby dinosaur skull where the front half was invisible but the rear half showed up in the image. The problems with imaging dinosaur baby bones are the same as imaging of embryonic remains and come from differences in density.

Eggshell can be chemically analyzed. First the eggshell must be cleaned of all contaminants, like the rock in which it was found and then given an ultrasonic bath. One technique uses and scanning electron microscope microprobe to fire electrons at the eggshell. When they strike the atoms in the eggshell they emit X-rays. A detector picks up the X-rays and a computer analyzes them and depicting the emitted X-rays as peaks on a line graph. Each peak corresponds to certain elements.

X-ray diffraction is similar, only X-rays directly bombard powdered eggshell. When the X-rays hit the atoms in the eggshell powder some of them are diffracted. The angle and intensity of the diffraction depends on the elements present in the eggshell. The peaks are compared to a database to identify the elements.