Final answer:
It is difficult to conclusively state which 2 dinosaurs were originally included in Pachycephalosauridae, but one could reference members of this group such as Pachycephalosaurus and Stygimoloch. These dinosaurs, known for their distinctively thick and domed skulls, are a part of the Ornithischia group.
Step-by-step explanation:
The Pachycephalosauridae is a group of dinosaurs within the order Ornithischia. The original dinosaurs included in the Pachycephalosauridae were primarily herbivorous and known for their domed and thick skulls. Unfortunately, the question lacks specific names of the 2 dinosaurs to be answered accurately. However, one could reference popular members of the Pachycephalosauridae family such as the Pachycephalosaurus and Stygimoloch as representatives, given their pronounced features. It's worth noting that the Ornithischia group is distinct from the Saurischia group which includes the dinosaur line that eventually evolved into birds.
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