The fossil bones contain more minerals than the chalk, and somehow the plants find them. Given enough time, they will also seriously damage them. I carefully traced the major roots out that were near the surface and cut them away from the fossil bones. The skull appeared to be completely disarticulated but most of the pieces seemed to be there. Note the location of the parietal foramen.
Scale is in centimeters.
This photo shows the same two bones from below. These bones comprise the top of the skull in mosasaurs. The parietal foramen is a primative opening in the skull for the pineal gland, a primative 'third eye' in some amphibians and reptiles. This photo shows the left side of the premaxillary. The specimen was initially identified as a Tylosaur on the basis of the rostrum extending beyond the front teeth.