It’s practically impossible to come to any definite conclusions, but a great deal of this area of paleontology remained a mystery to researchers even after Varricchio’s contribution.
Despite all the technology, different fossils, and different minds working to uncover the mysteries, nothing definitive came to light. FSU professor Erickson gave a statement in 2017 to the university summarizing: “Did [dinosaur] eggs incubate slowly like their reptilian cousins, crocodilians and lizards? Or rapidly like living dinosaurs, the birds?”
We have no way of studying an on-going life cycle of dinosaurs, which means it's impossible to see how the creatures grew as time went on.
Thanks to fossils, we have snapshots of growth and development, but that's like looking at pictures of a baby, and teenager, and an adult, and knowing everything about the person's life – growth doesn't work that way. But, experts can at least theorize, which led them to believe the incubation process for dinosaurs was similar to today's birds.
Until, however, David J. Varricchio from Montana State University published a paper in 2013 putting forth a different theory. Thanks to his study he's found that certain dinosaur eggs had lots of pores, which suggests they had been covered up underground – before they were scheduled to hatch.
If you've ever seen videos of baby turtles pulling themselves out of the sand and crawling toward the water, you've seen a similar process. This, in turn, suggests that the incubation process does have more in common with modern-day reptiles than birds.
Erickson hoped to answer the question once and for all, and he decided to throw caution and convention to the wind in his methods.
Erickson knew that reptiles, just like humans, produce a substance known as dentin on a daily basis. Dentin is found in teeth, and it's a tissue that mineralizes up in layers over time, forming a tough core and keeping teeth strong and secure.
Since taking a course in vertebrate paleontology, Erickson was destined to find his way to dinosaurs. He earned the second-highest grade out of five hundred students, and his professor invited him on a field expedition in Montana to collect dinosaurs for the university museum.
The professor became impressed with Erickson's ability to visualize fossils as living animals and encouraged him to enter paleontology. Erickson says that in many ways, the field found him.