Robert also sent in a link to www.dailymail.co.uk/sciencetech/article-8432207/ … the second biggest egg ever – found just off the West Antarctic peninsular. It was produced by a marine creature as large as a dinosaur, a sea lizard known as a mosasan. The rocks where it was found also contained skeletal parts of mosasaurs and other prehistoric sea creatures such as the plesiosaurs (both young and adult). Seems like another catastrophic event of some kind was involved in their burial and preservation.
The environment at the time was ice free and much warmer with forests, quite unlike modern Antarctica and the small islands around it. It seems to have been a sort of nursery site in shallow water – but was some how overwhelmed and buried in sediment that became rock. However, the egg itself is a mystery. Did the big beast deposit on the beach or did it hatch in open water?