Pachycephalosaur Tooth-Montana 02

 Taxa: Pachycephalosaurus sp.

Geology: Hell Creek formation

Age: Cretaceous-Maastrichtian

Locality: Garfield County, Montana

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Pachycephalosaurs

Pachycephalosaurs were a group of bipedal, herbivorous or omnivorous dinosaurs that lived during the Late Cretaceous period. They are best known for their distinctive thickened skull domes, which could have been used for display, defense, or intraspecific combat. These dinosaurs were relatively small to medium-sized, with a robust build, short arms, and long legs, and were part of the Marginocephalia group, which also includes ceratopsians. Pachycephalosaurs were likely social animals, living in groups, and their thick skulls may have played a role in head-butting or other forms of social interaction. Fossils have been found in North America and Asia.

Pachycephalosaurs from the Hell Creek Formation are known from fragmentary fossil evidence, with species such as Stygimoloch and Pachycephalosaurus being among the most recognized. The Hell Creek Formation, which dates to the late Cretaceous period (around 66 million years ago), preserves a rich fossil record of dinosaurs from the Maastrichtian age, including these thick-skulled herbivores or omnivores. Pachycephalosaurs from this formation are notable for their domed skulls, which were likely used for head-butting or display. These dinosaurs were small to medium-sized, with a bipedal stance, and they likely coexisted with other famous species from the Hell Creek Formation, such as Triceratops and Tyrannosaurus rex. Their presence in this formation helps us understand the diverse ecosystems that existed at the end of the Cretaceous.

Hell Creek formation

The Hell Creek Formation is a geologic formation in North America, primarily spanning Montana, North Dakota, South Dakota, and Wyoming. It dates to the Late Cretaceous period, around 66 million years ago, and is famous for its rich fossil record, including dinosaurs like Tyrannosaurus rex, Triceratops, and Edmontosaurus. It also contains evidence of the Cretaceous-Paleogene (K-Pg) extinction event, including an iridium layer associated with the asteroid impact that contributed to the mass extinction of non-avian dinosaurs. The formation also preserves fossils of plants, mammals, fish, and reptiles, providing valuable insights into prehistoric ecosystems.