Dacentrurus | An Intriguing sDino from of the Late Jurassic

Dacentrurus was a member of the Stegosauria group, a family of dinosaurs known for their distinctive plated backs and spiked tails. These herbivores were a testament to the incredible biodiversity that existed during the Late Jurassic to Early Cretaceous period. Dacentrururs remians have been found all over Western Europe, dating back around 155 tol 125 million years. Named after an impressiv row of spikes on its tail, D. armatus is a fascinating dinosaur.

Dacentrurus Key Facts

Dacentrurus Taxonomy and Timeline

Dacentrurus, a fascinating member of the Stegosauria group, was named from the Greek words ‘da-‘ meaning ‘very’ or ‘full of’, ‘kentron’ meaning ‘point’, and ‘oura’ meaning ‘tail’. This paints a vivid picture of a dinosaur with a tail bristling with spikes. This name serves as a reminder of the creature’s defensive capabilities, a key aspect of its survival strategy.

Dacentrurus belongs to the Ornithischia order, the Thyreophora clade, the Stegosauria suborder, the Stegosauridae family, and the Dacentrurinae subfamily. Dacentrurus armatus is the type species of this genus, named in 1875 by Richard Owen based on a skeleton found in Swindon, England.

It lived during the Late Jurassic to Early Cretaceous period. This era was characterized by a warm climate, devoid of polar ice caps, and a flourishing of dinosaurs. The robust build and defensive armor of Dacentrurus was a testament to the incredible biodiversity that existed during this period.

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Discovery & Fossil Evidence

The discovery of this dinosaur, originally known as Omosaurus, dates back to 23 May 1874, when James Shopland of the Swindon Brick and Tile Company reported a fossil skeleton found in their clay pit–the Swindon Great Quarry–to Professor Richard Owen. The specimen was encased in an 8 foot high clay nodule that crumbled into several pieces during an attempt to lift it. These pieces were eventually transported to London in crates with a total weight of 3 tonnes. The bones were subsequently partially uncovered by Owen’s preparator, the mason Caleb Barlow.

Owen named and described the remains in 1875 as the type species Omosaurus armatus. The generic name is derived from Greek “omos”, or upper arm, in reference to the robust humerus. The specific name armatus can mean “armed” in Latin and in this case refers to a large spike that Owen assumed was present on the upper arm.

The holotype, BMNH 46013, was found in a layer of the Kimmeridge Clay Formation dating from the late Kimmeridgian. The main nodule fragment contained the pelvis, a series of six posterior dorsal vertebrae, all sacrals and eight anterior caudal vertebrae, a right femur, and some loose vertebrae. In all, thirteen detached vertebrae were present in the material. An almost complete left forelimb was contained by another loam clump. Additional elements include a partial fibula with calcaneum, a partial tibia, a right neck plate, and a left tail spike.

In 2021, remains attributed to Dacentrurus sensu lato (in the broad sense) were reported from the earliest Cretaceous Angeac-Charente bonebed of France. These consisted of a partial skeleton that included parts of the braincase, vertebrae, ribs, and phalanges.

Dacentrurus Size and Description

Along with Stegosaurus, Dacentrurus was one of the largest species of stegosaur with some specimens estimated to have reached 26 to 30 ft in length, 5.9 ft in hip height, and wighing 5.5 to 8 US tons. For a stegosaur, its gut was especially broad and its exceptionally wide dorsal vertebrae centra indicated a massive rump. The hindlimb was rather short but the forelimb relatively long, largely because of a long lower arm.

Short description of Dacentrurus

Although it is considered to have the same proportions as Stegosaurus, its plate and spike configuration is known to be rather different as it probably had both two rows of small plates on its neck and two rows of longer spikes along its tail. The holotype specimen of Dacentrurus armatus contained a small, blunt, asymmetrical neck plate, and a large pointed tail spike. The tail spikes were held horizontally, not vertically as is often depicted. The tail was also highly flexible as indicated by the presence of a large number of ossified tendons, which would have made the tail a much more effective weapon.

Its skull is not well known as no complete skulls have been found but it is assumed to have been small and narrow like other stegosaurs. Their teeth were small, triangular, and flat; they were serrated and symmetrical and used for shredding and tearing plant matter.

Size and Weight of Type Species

Its size has been a subject of debate among paleontologists. Some early estimates suggested that it could reach lengths of up to 33 ft and weigh as much 5.5 to 8 US tons. However, more recent studies have suggested that these estimates may have been too high. A comprehensive study of the available fossil material by Susannah Maidment and colleagues in 2015 suggested that a more accurate estimate for the length of Dacentrurus would be around 26 ft, with a weight of around 2.5 tons.

Despite these discrepancies, there is no doubt that it was a large dinosaur. I can’t stress enough that it’s quite normal that size estimates vary and only new finds can provide more information. Its size would have made it one of the largest herbivores in its environment and its distinctive armor and tail spikes would have made it a formidable opponent for any predator.

The Dinosaur in Detail

With its distinctive armor and tail spikes, D. armatus is an example of the incredible diversity and adaptability of dinosaur life. Its unique features reflect a highly specialized lifestyle and a remarkable set of survival instincts. The large spikes on its tail, for instance, were likely used as a defensive weapon against predators. The presence of these spikes along with the dinosaur’s large size and robust build suggest that Dacentrurus was a slow-moving but formidable creature.

One of the most notable specimens of Dacentrurus is the holotype specimen, which was discovered in the late 19th century. This specimen includes a nearly complete left forelimb, a series of vertebrae, and several other elements. The preservation of these elements has allowed scientists to gain valuable insights into the anatomy and behavior of Dacentrurus. For instance, the long lower arm suggests that Dacentrurus may have been capable of rearing up on its hind legs, perhaps to reach higher vegetation or to defend itself against predators.

The study of Dacentrurus and other stegosaurs has also shed light on the evolution and diversity of this fascinating group of dinosaurs. Stegosaurs are known for their distinctive plates and spikes, but the exact arrangement and function of these features can vary widely between different species. The unique configuration of plates and spikes in this species sets it apart from other stegosaurs and underscores the incredible diversity of this group.

The Dacentrurus in its Natural Habitat

This was a creature of the Late Jurassic period during a time when the world was a very different place than it is today. The climate inEurope was warm and humid and the landscape was dominated by lush forests and vast swamps. These environments would have been teeming with life, providing ample food and shelter for a large herbivore like this.

As an herbivorous dinosaur, Dacentrurus would have fed on a variety of plant matter. Its small, flat teeth suggest that it was adapted for shredding and tearing vegetation rather than for grinding or crushing. This, along with the dinosaur’s large size and long neck, suggests that it may have been a browser that fed on the leaves and branches of trees and shrubs.

Its social behavior is not well known but it is possible that these dinosaurs lived in herds or family groups. The presence of multiple individuals in some fossil sites suggests that they may have been social animals. However, more evidence is needed to confirm this. Regardless of its social behavior, there is no doubt that it had a significant presence in its environment. Its large size and distinctive armor would have given it a strong presence and its feeding habits may have had a large impact on the vegetation and landscape of its habitat.

Interesting Points about Dacentrurus

Contemporary Dinosaurs

D. armatus shared its world with a number of European dinosaurs. Among them were Hylaeosaurus, Allosaurus, and Hypsilophodon to nmae but a few. Each of these dinosaurs played their part in their complex web of survival and competition.

Hylaeosaurus, smaller in size, might have been a frequent sight around our main dinosaur. Their coexistence could have been marked by a delicate balance of competition and indifference. Dacentrurus with its impressive size might have had little to fear from Hylaeosaurus. However, the smaller dinosaur would have had to navigate its existence carefully to avoid becoming an unintended threat.

Hypsilophodon would have played a very similar role in this environment. While it lacked the same defensive system as Dacentrurus, it would have been a competitor for the same resources. Together, these herbivores would have navigated their environment through very different lifestyles with the same goals in mind.

Allosaurus on the other hand, presents a different dynamic. As a larger and more formidable presence it must have been a potential predator. Its interactions with Dacentrurus would have been marked by a tense undercurrent of potential conflict.

List of All Dinosaurs

We have created a list of all dinosaurs we have covered here, sorted across the seven main groups of dinosaurs. We also include information about their type of diet, (omnivore, herbivore or carnivore) and the time they lived.

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Sources

Article last fact checked: Joey Arboleda, 06-08-2023

Featured Image Credit: Danny Cicchetti, CC BY-SA 3.0 https://creativecommons.org/licenses/by-sa/3.0, via Wikimedia Commons