Pachycephalosaurus lived in the late Cretaceous Period, 72 – 66 million years ago, in what is now the western United States and Canada. This was the same time and place that Tyrannosaurus and Triceratops lived. Pachycephalosaurus probably walked on two legs with its tail stretched out behind it and its head leaning forward to balance it. It was about 15 feet long, and weighed almost 1000 pounds. None of that makes it unusual. But when people take a closer look at this dinosaur, it definitely stands out.
Pachycephalosaurus means “thick-headed lizard.” It is a bizarre creature for several reasons. First, the name is weird, even for a dinosaur, because it has so many syllables. If you ever want to impress someone, just rattle off that name without any pauses.
Second, it had nine to ten inches of solid bone in a dome on top of its skull, twenty times thicker than the skulls of most other dinosaurs. That’s a huge difference!
Scientists don’t know for sure why this dinosaur had such a thick skull, but some of them think Pachycephalosaurus liked to butt its head into things, especially other dinosaurs. Head-butting is used by modern animals, such as bighorn sheep or mountain goats, to establish dominance.
The winner controls a territory and impresses the females. The thick skull of Pachycephalosaurus might have protected its brain when it collided with another dinosaur. Scars on the domes of some skulls also support this idea.
But some scientists doubt head-butting was possible, saying the shape of its neck makes it unlikely its spine could withstand a head-on collision. And, the top of its head is rounded, so not much surface would collide with the other dinosaur. These scientists think that maybe Pachycephalosaurus used glancing blows to the side while fighting others to see who would control a territory. It also might be that Pachycephalosaurus having a big head just helped males to attract females. One thing scientists do agree on is that its thick skull wouldn’t have been much good as defense if it were attacked by Tyrannosaurus because the rest of its body had no defenses.
However, it wasn’t just the thickness of the skull that made this dinosaur weird. Across the back of the dome and on its snout, it had large circular bumps (see skull above). Bumps aren’t all that weird, but scientists think most of the bumps started out as spikes, flattening as the dinosaur grew older. They have found skulls of smaller dome-headed dinosaurs that were thought to be different species of dinosaurs, such as one called Dracorex hogwartsia, which means “the Dragon King of Hogwarts” (named for Harry Potter’s school). They are now thought to be juvenile pachycephalosaurs. It seems odd that spikes would flatten into bumps as the dinosaur grew up, as spikes seem more useful than bumps, but, as I said, this is a weird dinosaur.
Another strange thing was its teeth. In the back of its mouth, it had wide, leaf-shaped teeth, similar to those found in many plant-eating dinosaurs. According to paleontologist, Philip Currie, “We have always been somewhat mystified by what these animals were eating, but I think the teeth at the back of the jaws clearly show it’s an herbivore.” But in 2018, paleontologists reported finding a more complete jaw, and they couldn’t believe what it showed. In the front of its mouth, it had sharp, triangular teeth, that were more like a carnivore.
Paleontologist, Steve Brusatte, said, “It had the combination of a beak with these very sharp, steak knife-like serrated teeth … They must have been eating some kind of meat. Why else would you have steak knives at the front of your mouth?” This combination is very unusual. Scientists have suggested that this means it might be an omnivore, eating both plants and meat. The meat would have been small animals, such as lizards, frogs, or even small mammals; the plants would have been ferns, leaves, and conifer needles.
All in all, Pachycephalosaurus certainly qualifies as a strange and weird dinosaur. It’s one of my favorites, and I hope it is now one of yours.
Title Image provided by DKfindout
Sources (Click Me)
Sykes, Ben. “Seventeen Unusual, Bizarre, and Downright Weird Dinosaurs.” BBC Science Focus Magazine. 31 May 2018. https://www.sciencefocus.com/nature/17-of-the-weirdest-dinosaurs-to-walk-the-planet/
“Pachycephalosaurus.” Find Out. Dorling Kindersley Limited. 2022. https://www.dkfindout. com/us/dinosaurs-and-prehistoric-life/dinosaurs/pachycephalosaurus/
Pickrell, John. “Vegetarian Dinosaur May Have Actually Eaten Meat, Skull Suggests.” National Geographic. 24 Oct. 2018. https://www.nationalgeographic.com/science/article/news-vegetarian-dinosaur-ate-meat-pachycephalosaurus-paleontology
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