2 Bizarre Dinosaurs From Dog-Sized Pachycephalosaurs Genus Discovered in North America

Two new dinosaur species were discovered and both belonged to the same genus. They reportedly lived in the last part of the Cretaceous period (around 145 to 66 million years ago).

2 New Dinosaur Species Discovered

The two species of dinosaurs were discovered in southern Alberta and eastern Montana, respectively. Both existed before the global extinction event that wiped off all non-avian dinosaurs and most plant and animal species on Earth. It is believed that the event, which took place some 66 million years ago, was caused by a massive asteroid collision.

The species is part of the dog-sized pachycephalosaur genus of dinosaurs, which is distinguished by a distinctive skull characteristic. Both would have been around six feet long, from nose to tail, with an orange-sized dome on their heads.

In both instances, Woodruff and associates defined the two new species using a single skull bone called the squamosal. The species discovered in Montana has been named Phaerotholus triregnum by the researchers, and the one discovered in Alberta has been named Phaerotholus lyonsi.

"Pachycephalosaurs are the 'dome-headed' dinosaurs. They walked around on two legs and ate plants, but what makes them so iconic and bizarre is that most of them had a large spherical mass of solid bone on the top of their heads," Cary Woodruff, a paleontologist with the Phillip & Patricia Frost Museum of Science and author of the study, explained.

"The largest member of this group was called Pachycephalosaurus, and it could have a dome around 9 inches thick!"

The behavior of pychosaurs, particularly the purpose of their domed heads, is a subject of intense scientific inquiry and discussion. According to Woodruff, some paleontologists believe they butted heads like bighorn sheep with their domed heads. Some believe that this ornate headdress was used to distinguish between different species.

Some people believe that the domes served as a kind of visual billboard, showcasing information such as species identification, age, and possibly even gender. The domes became larger and larger as the animals aged.

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More About The Pachycephalosaur

Pachycephalosaurus is a genus of massive and uncommon dinosaurs from the Late Cretaceous Period (between 100 million and 65.5 million years ago) that have been discovered as fossils in sediments in North America. The bipedal Pachycephalosaurus, which reached a maximum length of 16 feet (5 meters), had powerful hind limbs and relatively less developed forelimbs.

The high, dome-shaped cranium of the Pachycephalosaurus is an uncommon and distinguishing feature. It is generated by a thick mass of solid bone growing over the tiny brain. The temporal apertures that were typical of the skulls of comparable taxa were concealed by this bone development.

The unique appearance was further enhanced by the abundance of bony knobs at the sides and front of the head.

These dinosaurs featured a range of skull forms, and they were also found in Mongolia. The dome was flat rather than thick in the most primitive forms. A huge sagittal crest with spikes and knobs projecting down and back from the sides of the skull, or broad domes formed like kneecaps, were features of late forms. Although it has been proposed that these animals were head butters, akin to living rams, the arrangement of the domes refutes this theory.