Pachycephalosaurus wyomingensis, known for its thick, domed skull, inhabited the Late Cretaceous period. This herbivorous dinosaur lived in North America, walking on two legs with a distinctive bipedal stance. It is believed to have used its robust skull for head-butting in social interactions or defense.

Pachycephalosaurus wyomingensis was native to what is now North America, specifically in the regions that are currently part of the United States and Canada. Fossils have been primarily found in the Hell Creek Formation, which spans parts of Montana, South Dakota, North Dakota, and Wyoming.

During the Late Cretaceous period, the region was characterized by a warm, subtropical climate. It included a variety of environments such as floodplains, river systems, and coastal plains with abundant vegetation, including conifers, ferns, and flowering plants.

Pachycephalosaurus wyomingensis is believed to have been a herbivorous dinosaur, feeding on a variety of plants. Its thick, dome-shaped skull suggests it may have engaged in head-butting behavior, possibly for intraspecies competition or defense. The species likely occupied niches within mixed woodland and open areas where it could browse for vegetation.