#stegosaurids

The distinctive array of four spikes on the end of stegosaurines' tails is called a thagomizer.

Archovember Day 25: Stegosaurus stenops

One of the most famous dinosaurs and certainly the most famous stegosaurian dinosaur, Stegosaurus certainly has a recognizable silhouette.

The double row of plates on its back are its most defining feature. The number of plates vary, Stegosaurus could have had between 17 and 22 of them, and they continued growing after the animal reached its adult size. They were attached to the skin, not the bone, so its hard to tell how they were arranged on the back from fossils, but the most recent evidence shows that they possibly grew in an alternating pattern, rather than side by side. It is still unknown what they were used for: they were too fragile to be armour and not really big enough to have an effect on thermoregulation (especially if Stegosaurus was endothermic.) It is possible that they were used to attract mates, or simply just to make the animal appear larger and more threatening.

The other most defining feature is the Stegosaurus’ 4 long tail spikes: dubbed the “thagomizer” by cartoonist Gary Larson. Stegosaurus likely used these spikes for defense against predators, as wound holes fitting them have been found in Allosaurus fossils.

It also had a fairly long neck, which it used to graze on plants, perhaps even standing on its hind legs to reach low-hanging branches. It’s hind legs were longer than its front legs (though not quite as drastic as older illustrations) so it was probably a low to mid-level browser.

Originally thought to be a very primitive stegosaurian, current cladistic analysis places Kentrosaurus as one of the most derived stegosaurs, and a close relative to Stegosaurus.