Dinosaur Egg - Excavation and Preparation

Excavation and Preparation

Fossil dinosaur eggs are usually not found until exposed by the natural processes of erosion. As the fossil eggs are eroded, fragments of shell are gradually scattered over hillsides or down gullies. Prospectors who eventually find the eggshell fragments then attempt to ascertain their source.Sometimes the source of the eggshells will be a preserved nest. When an egg is finally located the area around it is excavated to check for additional eggs. Once the layout of the clutch of eggs is ascertained, the area around it is excavated down to significantly below the estimated depth of the eggs. For some dinosaur species this process is complicated because they laid eggs in several layers. The excavators would then partially cut under the eggs and covered with material like newspaper, tissue, or tin foil. Afterword, the entire block is covered in multiple layers of plaster-soaked strips of burlap. After the plaster is dried, the block is undercut the rest of the way and turned over.

After transport to the lab fossil the bottom of the block is typically opened first since it usually is the best preserved side of the eggs. The rock is gradually cleaned away with small pneumatic engraving tools, dental picks, needles and X-Acto blades. The work can be tedious and practitioners need patience t be able to clean the fossil eggs without damaging them. Even superficial damage to the eggs can cause a significant loss to science because a fossil egg's surface ornamentation can be needed to identify the egg's oospecies. Kenneth Carpenter describes the decision to conclude preparation as a judgement call with costs and benefits. If the eggs are completely extracted it can be difficult to reconstruct their exact positions in relation to each other. If they're left partially encased in rock it can conceal the fact that they hatched. Eggs imported from China during the mid-1990s were kept partially encased in rock, which formed a sort of pedestal at the base of the specimen. When these specimens were subjected to X-Rays and CAT scans a gap in the eggshell could be seen on the egg's original upper surface. This gap is the hole punched in the shell by the baby dinosaur when it hatched. Fossil dealers prepare nests like this because the unhatched undersides of the egg are more cosmetically appealing an increase the likelihood of sales.