http://www.sciencedaily.com/releases/1998/10/981026200356.htm
“...The oldest previous evidence for reptile-nesting sites include 110 million-year-old sea turtle nests from the Front Range of Colorado and nests of a dinosaur group known as Hadrosaurus from Montana, estimated to be about 90 million years old.
Hasiotis first discovered the ancient reptile nests while conducting research in Arizona’s Petrified Forest in 1996. He invited Martin to the site in 1997 and the two returned to conduct additional research in 1998. Surrounding some of the ancient nests are broad, shallow pits or irregular, trampled ground that appears to contain vertebrate tracks, Hasiotis said. The researchers also discovered distinct tracks of phytosaurs about one-half mile from the nesting sites.
The walls in the interior of the nests appears to have been compacted down by the inhabitants. Contemporary crocodile mothers tend to stay near their nests and guard them from predators, while turtles leave their nests immediately after the egg-laying process, said Hasiotis...
(I’m simply suggesting that not all ‘dinosaurs’ laid their eggs in a shallow hole and walked away...)