MEET STEGOSAURUS Discovery and name The name Stegosaurus means ‘roof lizard’ in Greek. Early reconstructions of Stegosaurus were incorrect, with large plates laying flat along the back like the segments of a turtles shell. Stegosaurus was named by the famous palaeontologist Othneil Charles Marsh in 1877. Lived where and when? Stegosaurus lived in the Late Jurassic (approximately 155-145 million years ago) in North America. The bones of Stegosaurus have been collected from Colorado, Wyoming and Utah. Size and growth Stegosaurus was the largest member of the Family Stegosauridae, measuring nine metres long, three metres high and weighing two tonnes. By looking at the internal structure of bones, palaeontologists think that Stegosaurus had a slower growth rate and metabolism compared to other similarly-sized dinosaurs. The plates on the back of juvenile Stegosaurus were relatively smaller and more rounded than those of adults. Diet Stegosaurus had a narrow muzzle and a toothless beak, for selectively plucking vegetation such as ferns, and cycads. The jaws were relatively weak and lined with small teeth, allowing it to only bite through thinner branches and soft, low lying vegetation. Plates and spikes Many uses have been suggested for the alternating rows of back plates on Stegosaurus. Although it was thought that these plates were too fragile for defence, they were covered in keratin, the same material as our fingernails! This would have increased the size and strength of plates. It has also been suggested that plates may have been used for display or to help regulate body temperature. The spikes on the tail of Stegosaurus are called thagomizers. They were probably covered in keratin, increasing strength and length. Wounds on the bones of the meat-eating dinosaur Allosaurus match the size and shape of thagomizers. Injuries have also been found on thagomizers, suggesting they were used for defense. 1/…1 .