Perhaps the least-cuddly dinosaur of all time, Kentrosaurus boasted some horrific weaponry—and a rather perplexing sex life.

1. Kentrosaurus Could Swing its Tail Spikes with Skull-Cracking Speed.

Get your hard hats ready! Dr. Heinrich Mallison of Tübingen University contends that this Tanzanian beast’s tail could swing in a 180-degree arc and create “forces greater than those sufficient to fracture a human skull." 

2. A Digital Kentrosaurus Was Created in 2005.

After scanning some Kentrosaurus remains currently housed in Berlin, Mallison created a digital skeleton model that allowed him to explore the animal’s range of motion. Among other things, this virtual avatar suggests that Kentrosaurus’ neck was quite flexible—all the better for spotting nearby predators.    

3. One Gender May Have Had Meatier Thighs.

Kentrosaurus femurs—or “thigh bones”—come in two varieties: robust and (comparatively) slender. If these groups represent different sexes, it’s worth noting that roughly two out of three specimens fall within the first category. Perhaps thicker-thighed individuals were females who formed harems around the less-abundant males.

4. Kentrosaurus Brain Casts Have Been Produced.

Few stegosaur brain cavities are well-preserved enough to give us a decent look at their shape. However, both Kentrosaurus and Stegosaurus itself have yielded enough material for the molding of brain casts, which might help scientists gather data on everything from relative intelligence to sense of smell.

5. It Grew Up Relatively Fast.

According to one recent study, Kentrosaurus matured more rapidly than its better-known cousin Stegosaurus. Average adults would have been about fifteen feet long—half the length of a fully-grown Stegosaurus.

6. There’s Been Some Debate Over Where its “Extra Spikes” Were Located.

Among Kentrosaurus’ most distinguishing features is a pair of broad-based spikes, which were initially thought to have been anchored to its hips. However, similar ornaments have been found anchored to the shoulders of fellow stegosaur Gigantspinosaurus, suggesting Kentrosaurus spikes were also located there.  

7. Kentrosaurus Might Have Squatted for Defense.

While strolling about, Kentrosaurus’ arms were held erect, but Mallison’s model found that the animal could also splay its forelimbs far out to each side, possibly in an attempt to guard its underbelly from carnivores.

8. Stegosaurs Like Kentrosaurus Had an Odd Center of Gravity.

Who’s up for some dino physics? Those muscular tails had a dramatic impact on stegosaur weight distribution. Their center of gravity was much further back than it is in most quadrupedal animals, resting all the way in the hip region. Thanks to this handy feature, stegosaurs could more easily rear up on their hind limbs and swing around their trademark tails.

9. Kentrosaurus’ Spikes Weren’t as Durable as Stegosaurus’.

Longer, skinnier spikes like Kentrosaurus’ may be better at piercing, but, as paleontologist Ken Carpenter points out, Stegosaurus’ thicker and proportionally shorter models were less likely to bend or break.

10. Kentrosaurus Sex Raises Wince-Inducing Safety Questions.

When your partner has gigantic, upward-facing spikes running all the way from her hips to her tail tip, making love requires caution. Mallison found that if an overeager male threw his hind leg over a mate’s backside, he’d castrate himself. “These prickly dinosaurs must have had sex another way,” says the scientist. “Perhaps the female lay down on her side and the male reared up to rest his torso over her.”