Newly discovered dinosaur had elaborate headdress

Credit: Jack Horner.

Dinosaur fossils have always fascinated scientists with their diverse and impressive properties.

From the horns of the triceratops to the crests of the hadrosaurs, these ancient creatures sported a variety of bony ornaments on their skulls.

However, recent evidence suggests that dinosaurs had even more complicated head decorations made of keratin, the same material found in human nails.

These structures were likely used by dinosaurs as visual signals or means of communication.

A new species of dome-headed dinosaurs, dating back around 68 million years, provides further evidence of these elaborate head decorations.

Pachycephalosaurs, which lived in the Cretaceous Period, were small to medium-sized herbivorous dinosaurs that walked on two legs and had a stiff tail for balance.

The newly described species is based on a partial skull, including its unique bowling ball-shaped dome, discovered in Montana in 2011.

Through detailed scans and analysis of the fossilized dome, paleontologists Mark Goodwin of the University of California, Berkeley, and John “Jack” Horner of Chapman University, California, concluded that the skull likely had bristles made of keratin, similar to a crew cut.

Goodwin explains that this type of bristly, flat covering makes “biological sense” because it could have served multiple functions, such as display or social interactions including visual communication.

The skull of this particular dinosaur also showed a healed gouge on the top, suggesting the creature had sustained a serious injury but survived long enough for new bone tissue to grow.

While some might conclude the injury resulted from a headbutt, Goodwin and Horner warn against it.

They believe the injury could have been caused by various factors, such as falling from a rock or encountering another dinosaur. They argue that the structure of pachycephalosaur skulls, which lack the necessary features for head butting, suggest that any headdress was primarily for display purposes.

Ornaments are common in dinosaur-descended reptiles and birds, used to attract mates and intimidate rivals. However, Horner and Goodwin argue that pachycephalosaur skulls lack the necessary padding to allow for headbutts without causing severe brain damage.

They suggest that it is important not to turn dinosaurs into mammals, but to understand them as bird-like reptiles and to study their behavior within that framework.

The team of paleontologists, which included the University of Toronto’s David Evans and the Royal Ontario Museum, named the new species Platytholus clemensi in honor of the late UC Berkeley paleontologist William Clemens, who collected numerous fossils in the same formation where the new species was found.

Pachycephalosaur skulls are relatively common in dinosaur beds because their sturdy domes are well preserved over time. Goodwin likens them to bowling balls in the fossil record because of their ability to withstand weathering and erosion.

Horner and Goodwin have a particular interest in pachycephalosaurs and have done extensive research on their evolution and development from juvenile to adult. Their results indicate that the bony structure of pachycephalosaur skulls does not permit head-to-head collisions or head-butting behavior.

The recent discovery of the partial skull of Platytholus clemensi revealed intriguing features that set it apart from other pachycephalosaurs in the same area. Blood vessels in the skull indicate the presence of tissue covering the dome.

If this covering were made of keratin, as is the case in birds or in ceratopsians such as the triceratops, the vessels would have dilated, leaving indentations or grooves.

However, the vessels ran vertically, suggesting the existence of an unknown vertical structure on the head.

According to Horner, pachycephalosaurs likely had an elaborate representation on their heads that remains a mystery. Because the domed heads of pachycephalosaurs changed shape and became more prominent with age, this suggests that they were used for sexual display and courtship.

Goodwin theorizes that dinosaurs could use color to distinguish sexes, similar to modern birds, which used bright colors on their faces and heads for visual communication.

Further research includes examining other pachycephalosaur skulls using CT scans and histology to determine if these dome-headed dinosaurs had additional elaborate headgear.

The combination of skull histology and CT scans has provided valuable data, supporting the hypothesis that the dome was covered with a keratin structure that had a vertical component, unlike other dinosaurs with hard skin or densely covering keratin.

The discovery of Platytholus clemensi adds to our understanding of the remarkable diversity and intriguing characteristics of dinosaurs.

Paleontologists continue to uncover new clues about these ancient creatures and their fascinating adaptations, shedding light on the extraordinary world that existed millions of years ago.

Source: UC Berkeley.

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