MEANING: Pointed lizard
PERIOD: Late Jurassic
CONTINENT: Africa
Kentrosaurus is a stegosaurid dinosaur from the Late Jurassic of Tanzania. Small for a stegosaur, adults measured around 4 m in length and weighed 700–1,600 kg. It had a small, elongated head with a beak used to bite off plant material that would be digested in a large gut. Kentrosaurus had a double row of small plates running down its neck and back, which merged into spikes on the hip and tail. The longest spikes were on the tail end and were used to actively defend the animal. There was also a long spike on each shoulder. The thigh bones come in two different types, suggesting that one sex was larger and more stout than the other.
Kentrosaurus is from the Jurassic. The Jurassic is a geologic period that spanned from the end of the Triassic, 201 million y ears ago, to the beginning of the Cretaceous, 145 million years ago. It is the middle period of the Mesozoic Era. The start of the Jurassic was marked by the major Triassic-Jurassic extinction event. The end, however, has no clear boundary with the Cretaceous. By the beginning of the Jurassic, Pangea had begun rifting into two landmasses: Laurasia and Gondwana, and the climate was warm with no ice caps. Life on land was dominated by dinosaurs, and the first birds appeared, evolving from a branch of theropods. The oceans were inhabited by marine reptiles, while pterosaurs were the dominant flying vertebrates.
Kentrosaurus is a stegosaurian. Stegosauria is a group of herbivorous ornithischian dinosaurs that lived mainly during the Jurassic period, though there are some members known from the early Cretaceous. Stegosaurian fossils have been found mostly in the Northern Hemisphere.
Stegosaurians were armored dinosaurs; together with the ankylosaurs, they make up a larger group known as the thyreophorans. An early evolutionary innovation was the development of spikes as defensive weapons. Over time, these developed into much larger plates and spikes as the species within the group grew to larger size. These plates usually tend to run in two rows down the back, and end as spikes, known as thagomizers, at the tip of the tail.