Do You Think Pachycephalosaurus?

Do y'all have any relatives that always bump heads? Even if it's over who gets to sit next to Gran Gran at the holiday table? Or which Star Wars fan-theory is more valid? Now that we've entered the frantic few weeks between Thanksgiving and Christmas/Hanukkah/Kwansaa/Solstice, that question may just be a little more on everyone's minds.

While some may hear the phrase "bumping heads" and think of old Uncle Ron or a big-horn ram, some may bring the Pachycephalosaurus to mind.

Mostly because it looked like it was born wearing a comically-small bicycle helmet.

Alive in Late Cretaceous North America, Pachycephalosaurus was actually one of the last non-avian dinosaurs to ever live. It was a herbivore that walked on two legs and waddled around with teeny-tiny, little arms. It probably spent 50% of its day eating small leaves, seeds, and fruits and running like hell from predators the other 50.

All in all, the species might have been just a small entry in some excavator's notebook if it weren't for that helmet-shaped head you've been dying to hear about.

Pachycephalosaurus sported a thick, domed skull that was oftentimes ringed with small spikes. The dome sat on the top of the skull--an area sometimes referred to as the brain-pan.

To quote noted vertebrate paleontologist, Joseph Peterson, "...the domes are just weird!" (Source)

Paleontologists have spent years attempting to understand these animals. The main reason for that being there are few fossils found of Pachycephalosaurus and even fewer that are wholly complete.

It was once thought that there was a much wider variety of pachycephalosaurs with a wide variety of heads, but it's hence been concluded that many fossils with flat domes or no domes at all were female and juvenile skulls. This indicts to experts that, like modern rams, their domes grew over time and grew more massive in males--a prehistoric example of sexual dimorphism!

And once paleontologists started thinking of them like rams, the question quickly became: did they butt heads?

The answers are still pretty unclear.

The domed shaped of Pachycephalosaurus's skull would have meant that butting males would have glanced off of each other instead of making full contact. But on the other hand, scientists are finding more and more evidence of sustained, minor skull injuries. It could be possible that, like giraffes and sheep, they butted their heads against others' flanks (sides) for dominance.

Unfortunately, because there are so few fossils of their ribs and sides, it's nearly impossible to tell which they practiced. Maybe it could be both! Until we find more remains, it'll just have to remain a mystery.

The Scientific Community should vote to name the debate over whether pachycephalosaurs head-butted or not.

I vote for "Schrödinger's Butt Head".

I'll expect a check if that name pans out...

Top left: photo credit to Raul Ramos at Art Station

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