The work paleontologists do absolutely blows my mind. When you think about the absurdity that they are counting the exact number of days a dinosaur was developing in its egg 65 - 100 million years ago. This isn’t the first time we’ve used counting rings to discover something astounding about the Hadrosaurus. We’ve also learned that she was an early grower, reaching her full size in 12-13 years. This is in stark contrast to the famous T. Rex, one of her primary predators, who would take a much longer 30-35 years to reach adulthood.
All of these numbers are so striking to me, its clear how specially evolved these creatures had become. Primates and other mammals we consider highly intelligent such as elephants and whales are pretty much the only creatures with such long develop cycles in the modern era. The Hadrosaurus was also the first dinosaur in which we discovered evidence that the young were born so immature that they required having food brought to them in their nest. Their societies had a large breeding ground, known as Egg Mountain, where hundreds of females would lay 30 or so 4 kilogram eggs each.
So we have a warm blooded animal which lived in a large community and deliberately cared for their young. All of this behavior sounds so advanced and not at all what we typically think of finding from reptiles. If only we could get more answers around how they communicated. With such a strong sense of community and attachment to parents, it seems pretty reasonable these animals had some fairly advanced communications methods, again, not something we associate with reptiles.