Stegosaurus

Steh-guh-SAW-rus

About the Stegosaurus

During the late Jurassic period 150 million years ago a very special familia thrived. The Stegosaurs, known for their giant plates and spikes on their back, the entire family is instantly recognizable. The Stegosaurus is the most well known in this family, featuring about 17 large bony plates on its spine that leaves scientists in wonder. Why did they have these giant plates? The most likely answer is for display and species recognition. Scientists think these plates were extremely colorful and were a way for males to attract a female, most likely waving them back and forth like a bird. Another theory from science is thermoregulation. The plates are giant and filled with blood vessels possibly working to help alleviate excess heat, similar to how dogs pant to regulate heat or how humans sweat. The final theory is they were used for protection. The Stegosaurus was the main prey for Allosaurus, a giant carnivorous theropod, they needed a way to protect themselves. Which is why scientists think it is the reason or part of the reason the Stegosaurus had plates. Which, it could be a mix of the three theories. But we can never know for sure why the Stegosaurus had those plates but we do know their main form of protection.

The thagomizer, a distinctive multi spiked, mace-like appendage found only on Stegosaurs. The Stegosaurus had a 4 spiked thagamizer for defending themselves. Found on the end of its tail it could deliver a powerful blow to anything threatening it. Scientists have found two fossils of puncture wounds in the side of an Allosaurus, telling scientists they used them for defence. One Allosaurus had a puncture wound in the hip and the other in the tail. Getting hit by a Stegosaurus’ tail in the Mesozoic guaranteed death for the perpetrator. Giving the Stegosaurus a powerful advantage in survival. The Stegosaurus was a herbivore grazing alongside early sauropods and small ornithopods so they needed the advantage to sustain their populations. 

The Stegosaurus wasn’t the brightest so its only advantage is sheer strength and its Thagamizer. This astounding 7 ton beast only had a brain the size of a hotdog. Giving this dinosaur one of the smallest brain to body ratios. Early 19th century scientists originally, because the Stegosaurus’ brain was so small, the cavity in its pelvis held a second brain coordinating the back half of it. This myth was disproven soon after when scientists hypothesized it was most likely used to hold a glycogen body that holds energy instead of a separate brain. In the Mesozoic the only way to survive is brawn or brain and evolution chose brawn for the Stegosaurus.