Dacentrurus ("very sharp tail"), originally known as Omosaurus, was a large stegosaur of the late Jurassic Period (154 - 150 mya). This dinosaur measured around 6 - 10 m (20 - 33 ft) in length. It had paired triangular plates down its spine, with four pairs of spikes on the end of the tail. This configuration closely resembles that of its relative, Kentrosaurus (see also: thagomizer). For unknown reasons, many books claim that Dacentrurus was a small stegosaur, when in fact finds such as a 1.5 m pelvis (measured at the acetabula) suggest that Dacentrurus was among the largest of them.