Dinosaur Egg - Research Techniques - CAT Scans

CAT Scans

CAT scans can be used to infer the 3D structure of a fossil egg's interior by compiling images taken of slices through the egg in small regular increments. Differences in density between the fossil and the infilling rock helps scientists understand the specimen's interior and have even been used to look for preserved embryo remains inside.However, as of Ken Carpenter's 1999 book on dinosaur eggs, all alleged embryos discovered using this method were actually false alarms. These were generally caused by variations in the type of infilling mineral or cement binding the infilling sediment into rock. Sometimes eggshell fragments that fell back into the egg when it hatched have been mistaken for embryo bones. Even when embryonic bones are known from an egg specimen they typically show up very poorly in CAT scans. This is because the bones had yet to fully mineralize so they were preserved 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. CAT scanners are among the largest and most expensive equipment used to study fossil eggs.