Kentrosaurus

MEANING: Pointed lizard

PERIOD: Late Jurassic

CONTINENT: Africa

Small for a stegosaur, Kentrosaurus measured about 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. Kentrosaurus had a double row of small plates running down its back, which merged into long spikes on the hip and tail. It also had a long spike on each shoulder, as defense against predators.

Kentrosaurus is from the Late Jurassic. The Late Jurassic was a dynamic period, spanning from about 162 to 143 million years ago. The continents were continuing to drift apart, and the supercontinent Pangaea had fully split into Laurasia in the north and Gondwana in the south. This continental rearrangement led to the formation of large inland seas and shallow coastlines that fostered diverse ecosystems. The climate during the Late Jurassic was warm and humid, with lush forests of conifers and ferns that stretched across much of the continents, creating a rich ecosystem where dinosaurs flourished the dominant land animals.

Dinosaurs continued to diversify through the Late Jurassic, with some of the most famous species evolving in this time. Many well-known sauropods, such as Brachiosaurus and Apatosaurus roamed the land, exhibiting niche partitioning with their selectively distinct neck positions. Alongside them, stegosaurs became widespread, their plates and spikes making them one of the era's most recognizable groups. Theropods like Allosaurus and Ceratosaurus were the apex predators, evolving large, powerful bodies and sharp teeth that allowed them to hunt the gigantic herbivores. The early evolution of birds was taking place, setting the stage for the numerous species that would fill the skies in the eras to come.

Unlike the dramatic mass extinctions that marked the beginning and end of the Mesozoic, the Jurassic Period ended without a sharp boundary. As the continents continued to drift, ecosystems gradually transformed into unique habitats that supported the more specialized dinosaur species of the Cretaceous.

Kentrosaurus is a stegosaurian. Stegosauria is a group of herbivorous ornithischian dinosaurs best known for their distinctive back plates and tail spikes. They first appeared in the Middle Jurassic and were most diverse during the Late Jurassic, although a few persisted into the Early Cretaceous. Stegosaurian fossils have primarily been discovered in the Northern Hemisphere, particularly in North America, Europe, and Asia, with fewer remains found in the Southern Hemisphere. Their distribution suggests they were successful in a range of environments, from floodplains to more arid regions, though they eventually declined in diversity as other herbivorous groups rose to prominence.

Stegosaurians were part of a larger group called Thyreophora, which also includes the heavily armored ankylosaurs. Early in their evolutionary history, stegosaurs developed simple rows of bony osteoderms for defense. Over time, these structures became more elaborate, evolving into the tall, broad plates and formidable tail spikes that characterize the group. These plates typically ran in two rows along the back and may have served multiple purposes—including defense, thermoregulation, and display - though their exact function is still debated. At the end of the tail, most stegosaurs bore a set of long paired spikes which could have been used as a powerful weapon against predators.