Dacentrurus ‭(‬Very sharp tail‭)

Short Info

Dacentrurus ‭(‬Very sharp tail‭)

Phonetic : Da-sen-tru-rus.

Named By : Frederic Augustus Lucas‭ ‬-‭ ‬1902

Diet : Herbivore

Size : Estimated 6-8 meters long

Type of Dinosaur : Armoured Dinosaur

Type Species : D.‭ ‬armatus‭ (‬type‭)‬

Found in : England,‭ ‬France,‭ ‬Portugal and Spain

When it Lived : Late Jurassic, 154-150 million years ago

Dacentrurus (meaning “tail full of points”) initially called Omosaurus is an species of the genus stegosaurian dinosaur found in the Late Jurassic to Early Cretaceous (154 140 mya to 154 mya) of Europe. The species that is its type, Omosaurus armatus, was named in 1875, and was based on a skeleton that was found in a pit of clay within the Kimmeridge Clay in Swindon, England. In 1902, the genus was changed to Dacentrurus due to the fact that Omosaurus had been previously used to refer to the crocodylian. In 1875, about a dozen species were identified, but it is possible that Dacentrurus armatus was the only one that is legitimate.

Dacentrurus NHMthe paleobear, CC BY 2.0, via Wikimedia Commons

The remains of this animal are limited and much of its look is not clear. It was a massively built quadrupedal herbivorewith a dazzling array of plate and spikes.

Dacentrurus was a huge Stegosaurid. A few specimens have been estimated to have lengths of 7-8 meters (23-26 feet) and weigh as much as 5 t (5.5 small tons). Numerous books assert they believe that Dacentrurus was a tiny Stegosaur, however discoveries like the 1.5 meters (4.9 feet) wide pelvis suggest that Dacentrurus was one of the biggest of them all. The gut of a stegosaur was large and a huge rump can be seen by the large dorsal vertebrae centrala. The hindlimb was quite shorter, but the forelimb was is quite long, mostly because of the length of the lower arm.

Dacentrurus holotypeC. L. Griesbach, Public domain, via Wikimedia Commons

While Dacentrurus is thought to be having similar proportions to Stegosaurus however, the plate and spike arrangement is thought to be quite different, since it comprised two small plates around its neck, and two rows of more long spikes that ran along its tail. The Dacentrurus holotype armatus was a tiny, sharp asymmetrical neckplate and also contained an asymmetrical tail spike that could be part of the Thagamizer. The tail spike was sharp with cutting edges on its rear and front side.

Dacentrurus is often depicted as having a spike growing close to the shoulder, similar to Kentrosaurus. The accuracy of this representation or not is yet established.

On May 23, 1874 James Shopland of the Swindon Brick and Tyle Company told Prof. Richard Owen that their clay pit, known as the Swindon Great Quarry located below Old Swindon Hill at Swindon in Wiltshire has once again produced the fossilized skeleton. Owen was able to send William Davies to secure the specimen, which turned out to be enclosed within an eight-foot high clay nodule. When attempting to lift it all at once the clump of clay broke into a number of pieces. The pieces were later shipped in London in crates that had the total weight of 3 tonnes. The bones were then partially exposed by Owen’s pre-history teacher mason Caleb Barlow.

Owen has identified and listed the remains in 1875 , describing them as the species that was to be named Omosaurus armatus. The generic name comes from the Greek”omos,” “omos, “upper arm”, in reference to the humerus’s robustness. The exact name of armatus may refer to “armed” in Latin and in this instance, it refers to a massive spike that Owen believed to be present on the upper arm.

The Holotype, BMNH 46013, was discovered in a layer of Kimmeridge Clay Formation dating from the late Kimmeridgian. The principal nodule fragment includes the pelvis, a sequence of six dorsal vertebrae posterior as well as all sacrals, the eight caudal anterior vertebrae one right femur as well as a few loose vertebrae. All in all, thirteen detachable vertebrae can be found within the specimen. Additionally, a nearly entire left forelimb was encased by a second clump of loam. Other elements include a partially fibula that has calcaneum, the tibia is partially displaced, a neck plate on the right and the left-hand tail spike.

A variety of other species could be identified within the Genus Omosaurus. A part from the British Museum of Natural History collection was the specimen BMNH 46321, two spike bases that were discovered inside the Kimmeridge Clay by William Cunnington close to Wootton Bassett. Great Western Railway cutting near Wootton Bassett. They were Owen in 1877 was named Omosaurus hastiger, an term meaning “spike-bearer” or “lance-wielder” and the spikes were are pictured as being worn on the wrists of the beast. The year 1887 was the time John Whitaker Hulke named Omosaurus durobrivensis on the basis of a the specimen BMNH R1989 that was discovered at Tanholt near Eye, Cambridgeshire, the particular name being taken from Durobrivae. (That specimen is often believed to be found in Fletton, Peterborough, Cambridgeshire in the same location that Alfred Nicholson Leeds made most of his discoveries.) The specimen was later named the distinct Genus Lexovisaurus. The year 1893 was the time Harry Govier Seeley named Omosaurus Phillipsii, which was based on the femur specimen YM 498. It was the epithet that honored the famous John Phillips. Seeley claimed that this could represent the exact taxon that was Priodontognathus Phillipsii Seeley 1869. This has resulted in the misinterpretation because of its having the same name. that Priodontognathus was subsumed by the latter under Omosaurus. This is however wrong since both species possess distinct types of holotypes. “Omosaurus leedsi” is a nomen nudum that was used by Seeley on the label of CAMSM J.46874 which is a plate discovered in Cambridgeshire, the epithet honoring Alfred Nicholson Leeds. In 1910, Friedrich von Huene named Omosaurus vetustus based on the specimen OUM J.14000 of an femur discovered in the west bank of the Cherwell River, the epithet refers to “the ancient one”. In 1911, Franz Nopcsa named Omosaurus lennieri which is the epithet that honors Gustave Lennier, based on an 1899 skeleton fragment discovered within the Kimmeridgian Argiles d’Octeville near Cap de la Heve in Normandy, France. The specimen was destroyed in the bombing by the Allies of Caen in 1944.

As the two last Omosaurus species were named, it was well-known that Omosaurus was occupied by an “crocodilian” (in fact a phytosaur), Omosaurus perplexus Leidy 1856. In 1902, Frederick Augustus Lucas renamed the species into Dacentrurus. The name derives from Greek da da “very” or “full of” the word kentron, “point”, and oura, oura, “tail”. Lucas has only given a brand new combination name for the specie Omosaurus armatus. Dacentrurus armatus. However, in 1915, Edwin Hennig moved most Omosaurus species to Dacentrurus which resulted in Dacentrurus istiger Dacentrurus durobrivensis Dacentrurus phillipsi and Dacentrurus lennieri. However, it was usual for researchers to employ the term Omosaurus as opposed to the name Omosaurus until the middle of 20th century. D. vetustus was earlier named Omosaurus (Dacentrurus) vetustus in the work of von Huene, was included in Lexovisaurus as an Lexovisaurus vetustus species in 1983, but the assignment was subsequently rejected by both editions of Dinosauria and O. vetustus has become the most common species of Eoplophysis.

As of the year 2021, remains that were attributed to Dacentrurus sensu lato were identified from the very first Cretaceous (Berriasian) Bonebed of Angeac Charente in France These consisted of fragments of a skeleton comprising portions of the braincase, vertebrae, ribs, and the Phalanges.

Source: Wikipedia