How did dr. jack horner's discovery of dinosaur nesting grounds support the hypothesis that birds evolved from a group of dinosaurs?

Dr. Jack Horner's 1978 discovery of a large dinosaur nesting ground at "Egg Mountain" in Montana provided evidence that dinosaurs laid eggs like birds and covered these eggs in nests, a practice employed by some species of living birds. The scientists were able to discover some fossils of baby individuals that suggested that the young stayed in the nest likely being fed by their parents, another characteristic practiced by living birds.