Description and Classification

Dacentrurus was a fairly large stegosaur, estimated to have reached lengths of about 7 to 8 meters (23 to 26 feet) and weighed several tons. Like other stegosaurs, it had a bulky body, a small head, short, stout forelimbs, and longer, more powerful hindlimbs, giving it an arched-back posture. It walked on all fours and was a slow-moving animal.

Its back was adorned with a series of bony plates and spines. Unlike the large, broad plates of its more famous relative, Stegosaurus, the plates of Dacentrurus are thought to have been smaller, narrower, and possibly more pointed, running in two rows. Towards the tail, these likely transitioned into, or were accompanied by, sharper spikes. The most formidable feature was its thagomizer – an arrangement of long, sharp spikes at the end of its tail, used as a defensive weapon against predators like Torvosaurus or relatives of Allosaurus that lived in the same European ecosystems.

Dacentrurus belongs to the group Dinosauria, specifically within the Ornithischia (bird-hipped dinosaurs). It is classified under the suborder Thyreophora, which includes armored dinosaurs, and the infraorder Stegosauria. Within Stegosauria, it is part of the family Stegosauridae. Some paleontologists place it in its own subfamily, Dacentrurinae, highlighting its unique features among European stegosaurs like Miragaia, which is known for its extremely long neck. The original name given to this dinosaur’s type species, Dacentrurus armatus, by Sir Richard Owen was Omosaurus armatus. However, “Omosaurus” was already used for another animal (a type of ancient crocodile-like reptile), so the genus was renamed Dacentrurus in 1902 by Frederic Augustus Lucas.

Distinguishing Features

Dacentrurus had several characteristics that set it apart from other dinosaurs, especially other stegosaurs:

• It possessed relatively small and narrow paired plates along its neck and back, which likely transitioned into more pointed spines towards the tail, differing from the large, kite-shaped plates of Stegosaurus.
• A formidable thagomizer at the tip of its tail, typically depicted with at least two pairs of long, robust spikes, which it could swing to injure attacking predators.
• A particularly robust pelvic girdle (hip bones), with some unique features in its vertebrae, contributing to its strong, stocky build.
• It was one of the largest stegosaurs found in Europe from the Late Jurassic, indicating its significant role in the herbivore communities of the time.

Paleoenvironment and Diet

Dacentrurus lived during the Late Jurassic period, specifically in the Kimmeridgian and Tithonian ages, around 157 to 150 million years ago. Its fossil remains are primarily found in Western Europe, with significant discoveries in the Kimmeridge Clay of England, and formations in France, Spain, and Portugal like the Lourinhã Formation. This region of Europe during the Late Jurassic consisted of a series of islands and coastal plains with a warm, subtropical climate. The environment would have included lush vegetation like ferns, cycads, and early conifers.

As a herbivore, Dacentrurus was a low-level browser. Its small head and beak-like mouth, filled with small, leaf-shaped teeth, were adapted for stripping foliage from plants close to the ground. It likely fed on soft, leafy vegetation rather than tough, woody material. Like other stegosaurs, it probably swallowed its food with minimal chewing, relying on gastroliths (swallowed stones) in its stomach to help grind down the plant matter for digestion. It shared its habitat with giant sauropods such as Lusotitan, predatory theropods, and other ornithischian dinosaurs.

Significance and Ongoing Research

Dacentrurus holds historical importance as one of the very first stegosaurian dinosaurs to be discovered and scientifically documented, even though it was initially given a name that was already in use. Its discovery in the 19th century provided early glimpses into this fascinating group of armored dinosaurs. Finding its remains across several European countries has helped paleontologists understand the distribution and diversity of stegosaurs beyond the well-known North American species.

Despite being known for over a century, research on Dacentrurus continues. Many aspects of its anatomy, particularly the exact shape, number, and arrangement of its dermal plates and spikes, are still debated due to the fragmentary nature of many fossils. Scientists are keen to find more complete skeletons to create a more accurate picture of its appearance and biology. Ongoing studies also focus on its precise evolutionary relationships with other stegosaurs, such as the long-necked Miragaia from Portugal, and how these European forms fit into the broader stegosaur family tree. Understanding the paleobiology of Dacentrurus, including its growth, movement, and defensive strategies, remains an active area of paleontological investigation, helping to reveal more about the complex ecosystems of Jurassic Europe.