The asteroid collision theory, which was brought to wide attention in 1980 by Walter Alvarez and colleagues, links the extinction event at the end of the Cretaceous period to a bolide impact approximately 66 million years ago. 
hatch a dinosaur egg
Groundbreaking research led by a Florida State University professor establishes a timeline of anywhere from three to six months depending on the dinosaur.
The biggest ramification from the study, however, relates to the extinction of dinosaurs. Given that these warm-blooded creatures required considerable resources to reach adult size, took more than a year to mature and had slow incubation times, they would have been at a distinct disadvantage compared to other animals that survived the extinction event.
"We suspect our findings have implications for understanding why dinosaurs went extinct at the end of the Cretaceous period, whereas amphibians, birds, mammals and other reptiles made it through and prospered," Erickson said.
Longrich, NR; Bhullar, BA; Gauthier, JA (2012). "Mass extinction of lizards and snakes at the Cretaceous–Paleogene boundary". Proc. Natl. Acad. Sci. U.S.A. 109 (52): 21396–21401.
Florida State University - January 2, 2017