* Post-hatching care

We saw in the earlier post that:
"The single most astounding feature of dinosaur pubic bones is that they formed a solid ring with a rather small opening."

Here is the expanded description of this situation, which shows another difference between dinosaurs and modern birds:
http://www.innerbird.com/pelvic_girdle/pelvic_girdle.html#pubic_bone
"It is possible to re-interpret the structural changes in the avian hip and tail as changes related to the evolutionary benefits offered by increased parental investment in offspring. The single most astounding feature of dinosaur pubic bones is that they formed a solid ring with a rather small opening. That opening severely limited the size of the egg and, therefore, the size of the hatchling. This anatomical bottleneck limited dinosaurs to reproductive strategies involving relatively large numbers of small young. Hatchlings may have needed foods and habitats that were different from those of the adult animals. Most animals that lay large clutches of eggs have post-hatching care by the adult that is somewhat hit-and-miss as it is in modern crocodiles, and not at all like the intense, dedicated effort made by many modern birds."

The fused pubic bones of the dinosaur led to dinosaur "post-hatching care" that was "not at all like many modern birds".