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Dome-headed Dino With Toothbrush-Like Bristles Discovered

Newly discovered dinosaur with bristle-like head ornamentation challenges theories on mating rituals.
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A new dinosaur that had rows of tough bristles like a toothbrush on its head has been discovered.

Researchers say the dome-headed Dino from 68 million years ago has traces of keratin, what fingernails are made of, sticking up from its skull.

Paleontologists say Platytholus clemensi, a type of pachycephalosaur was a plant-eating dinosaur that grew up to 15 feet (4.57 m) long and walked on two legs.

Discovered in 2011 in Montana’s Hell Creek Formation, the partial skull has now undergone CT scans that have revealed the keratin bristles, described as looking like a ‘brush cut’.

Dinosaur skulls sport an amazing variety of bony ornaments, ranging from the horns of Triceratops and the mohawk-like crests of hadrosaurs to the bumps and knobs covering the head of Tyrannosaurus rex.

There is a theory that the type of dinosaurs that pachycephalosaur belonged to bashed heads in courtship rituals much like some mammals do today.

But despite a gash being discovered on the skull which had healed up, the researchers say there is no real evidence to back this up and the discovery of bristles point to more of an elaborate headdress.

Dr. Mark Goodwin of the University of California, Berkeley, said: “We don’t know the exact shape of what was covering the dome, but it had this vertical component that we interpret as covered with keratin.

“A bristly, flat-topped covering biologically makes sense. Animals change or use certain features, particularly on the skull, for multiple functions.

“It could be for display or for social and biological interactions involving visual communication.”

Professor, John “Jack” Horner of Chapman University in Orange, California, added: “I would guess that there was something pretty elaborate up there.”

The head wound is about half an inch deep but they say it could have been caused by anything from a falling rock to a chance encounter with a tree or another dinosaur.

A CT scan of the dome. The dome-headed dinosaur from 68 million years ago includes remnants of keratin, the material that makes up fingernails protruding from its skull, a new study reveals. JACK HORNER AND MARK GOODWIN/SWNS

Talking of the head wound, Dr. Goodwin said: “We see probably the first unequivocal evidence of trauma in the head of any pachycephalosaur, where the bone was actually ejected from the dome somehow and healed partially in life,.

“We don’t know how that was caused. It could be head-butting — we don’t dispute that.”

And Horner added: “That’s the first place everybody wants to go — let’s crash them together. And, you know, we just don’t see any evidence of it, histologically,.

“Something hit the top of this guy’s head and damaged it, and it was something that was severe.

“But having a defense mechanism on your head is not a good idea, not for anybody.

“Any features, any accouterments that we find on the heads of dinosaurs, I think, are all display — it’s all about display.”

He said that reptiles and birds, the closest relatives to dinosaurs, have head ornamentation for display and rarely butt heads like mammals such as sheep.

They also lack a pneumatic chamber above the braincase, as found in bighorn sheep, which protects their brain from injury.

Horner added: “I don’t see any reason to turn dinosaurs into mammals, rather than just trying to figure out what they might be doing as bird-like reptiles.”

The study in the Journal of Vertebrate Paleontology said that blood vessels in the skull ended abruptly at the surface of the dome, indicating that the blood originally fed some tissue that was sitting atop the dome.

And as the vessels were perpendicular to the surface they most likely fed a vertical structure.

Horner said: “What we see are these vertical canals coming to the surface, which suggests that there might be keratin on top, but it’s oriented vertically.

“I think these pachycephalosaurs had something on top of their head that we don’t know about. I don’t think they were just domes. I think there was some elaborate display on top of their head.”

A histological thin section of the bony domed skull of the newly described pachycephalosaur. JACK HORNER AND MARK GOODWIN/SWNS

Dr Goodwin continued: “It’s reasonable to suggest that the covering over the dome may also have been brightly colored or subject to color change seasonally.

“The combination of cranial histology after thin-sectioning the skull and CT scanning gave us a much richer body of data and forms a basis for our hypothesis that there was a keratinous covering over the dome.

“We know the dome was covered with something, and we make a hypothesis that it had a vertical structural component, unlike Triceratops, T. rex and other dinosaurs, which had hard skin or keratin closely covering the bone.”

Dr. Goodwin also noted that the shape of the domed heads of pachycephalosaurs changed as the animals matured, becoming more prominent and elaborate as they approached adulthood.

That, too, would suggest they were used for sexual display and courting, though they may have been used to butt the flanks, as opposed to the heads, of male rivals.

He suspects that dinosaurs likely distinguished gender by color, as do most modern birds, such as cassowaries, peafowls and toucans, which have bright integumental colors around the face and head for visual communication.

Produced in association with SWNS Talker

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