Conditions had to be just right for dinosaurs to leave fossilized footprints

BBC : In a paper published in the Journal of the Royal Society Interface, Peter Falkingham of the University of Manchester and his collaborators explain why fossilized dinosaur footprints are so rare. According to the group’s computer simulations, the massive prehistoric animals left enduring prints only in thick, shallow mud. Lighter dinosaurs would not leave prints in the same kind of mud, which means that the absence of small prints next to large fossilized prints should not be taken as evidence for the absence of small dinosaurs.