Scelidosaurus ‭(‬limb lizard‭)

Short Info

Scelidosaurus ‭(‬limb lizard‭)

Phonetic : Skel-is-doe-sore-us

Named By : Richard Owen‭ ‬-‭ ‬1859

Diet : Herbivore

Size : Estimated 4 meters long

Type of Dinosaur : Armoured Dinosaur

Type Species : S.‭ ‬harrisonii‭ (‬type‭)

Found in : England,‭ ‬Dorset

When it Lived : Early Jurassic, 208-194 million years ago

Scelidosaurus (/,selIdoU’so:r@sScelidosaurus (/,selIdoU’so: having the intention of “limb lizard”, from Greek skelis/skelis, which means “rib of beef and sauros/sauros meaning “lizard’) is a genus of herbivorous ornithischian dinosaurs that are armoured that was discovered in the Jurassic of the British Isles.

Scelidosaurus harrisonii (1)5of7, CC BY-SA 2.0, via Wikimedia Commons

Scelidosaurus was a species that lived in its time in the Early Jurassic Period, during the Sinemurian to Pliensbachian stages, which occurred around 191 million years old. This genus , along with its closely related genera were found within the supercontinent Laurasia. The fossils of this genus have been discovered inside the Charmouth Mudstone Formation close to Charmouth within Dorset, England, and these fossils are famous for their outstanding preservation. Scelidosaurus has been referred to as the first complete dinosaur. It is also the most well recognized dinosaur in that part of the British Isles. Scelidosaurus is the sole recognized dinosaur in Ireland. However, a new description was only discovered in the year 2020. Following initial discoveries in the 1850s, the comparative anatomy expert Richard Owen named and described Scelidosaurus in 1859. One specie, Scelidosaurus harrisonii named by Owen in 1861, is believed to be as valid to this day, though a different species was suggested in 1996.

Scelidosaurus was around 4 metres (13 feet) long. It was a mostly tripedal animal that was fed on low-growing plants that were scrubby and the leaves of which were chewed off by the tiny, long head, which was taken care of in the gut. Scelidosaurus was lightly armored, secured by long, horizontal rows of oval keeled Scutes that spanned the back, neck and the tail.

A long-standing and well and the most “primitive” of the thyreophorans The exact location of Scelidosaurus within this group has been a subject of debate for more than 150 years. This was made more difficult by the lack of additional information about the evolution of dinosaurs that were armoured. There is evidence to suggest it is likely that Scelidosaurus could be an ancestor taxon to two major families of Thyreophora which includes the Stegosauria as well as Ankylosauria.

In the 1850s, the quarry’s proprietor James Harrison of Charmouth, West Dorset of England found fossils on the cliffs at Black Ven between Charmouth and Lyme Regis, that were extracted, possibly as raw materials to make of cement. A few of them he donated to the general surgeon and collector Henry Norris. The year 1858 was the time Norris along with Harrison sent fragments of limb bones to professor Richard Owen of the British Museum (Natural History), London (today the Natural History Museum). There was one left thighbone, specimen GSM109560. The year 1859 was the time Owen identified the species as Scelidosaurus in an entry on Palaeontology found in Encyclopaedia Britannica. The text of the lemma included a diagnosis, implying that the genus had been correctly identified and in fact a nudum nomen even though the definition was ambiguous and no specimens were found. Owen planned to call”hindlimb saurian” the name of the dinosaur “hindlimb saurian” but confused the Greek word skelos, skelos, “hindlimb” and skelis, skelis, “rib of beef”. The name was derived from the vigorous development in the hind leg. Afterward, Harrison sent an ankle joint as well as the claw (GSM 109561) as well as the juvenile specimen and the skull of Owen and was described in 1861. At that time, the kind specie Scelidosaurus harrisonii was identified after Harrison. The skull was later discovered to comprise a entire skeleton. It was first described by Owen in 1863.

British Palaeontologist David Bruce Norman has stressed the remarkable fact that Owen who earlier suggested the idea that dinosaurs were active quadrupedal creatures, has largely overlooked Scelidosaurus although it was able to serve as an excellent illustration of this theory and its fossil was among of the complete dinosaurs ever discovered. Norman explained this through Owen’s apex workload during the period of 1861, which included a variety of administrative duties, debates with colleagues and the research of numerous fascinating new extinct species, like Archaeopteryx. Norman further pointed out the fact that Owen in 1861 proposed the lifestyle of Scelidosaurus that was very unlike the current ideas It was the fish-eater of the sea and possibly sea-dwelling.

Owen has not yet indicated the existence of a Holotype. It was in 1888 that Richard Lydekker while cataloguing the BMNH fossils, identified certain hindlimb fragments that were described in 1861, specimen BMNH 39496, which consists of the lower portion of a femur as well as an upper portion of the fibula and tibia that together form the knee joint, which was the original specimen, implicitly naming them the lectotype for Scelidosaurus. Lydekker did not provide any reason for his decision, but possibly they were motivated by their size. Unfortunately, among the Scelidosaurus fossils were the remnants of a theropod dinosaur. The tibia and femur were therefore related to a carnivore. this was only discovered in 1968 when it was discovered by Bernard Newman. In the same year, B. H. Newman proposed that Lydekker’s decision to select an knee joint for the designation of the lectotype be officially removed through the International Commission on Zoological Nomenclature because the joint was , in his view from a species that was related to Megalosaurus. In the end, when Newman was already dead, Alan Jack Charig actually submitted a request in the year 1992. In 1994, the ICZN responded positively in an Opinion 1788 concluding to declare that the skull and the skeleton in the specimen BMNH R.1111 is the neotype for Scelidosaurus. It was discovered discovered in 1995, by Samuel Welles et al. Informally assigned to “Merosaurus”, which name is not yet validly published. It is more likely to be any belonging to the Coelophysoidea which is also known as Neoceratosauria. It has also been proven through Newman in addition to being was confirmed by Roger Benson that the original left thighbone GSM 109560 was a theropod.

The neotype skull was discovered within the Black Ven Marl or Woodstone Nodule Bed marine deposits from the Charmouth Mudstone Formation that date to early Sinemurian stage, which was around 191 million years back. It is comprised of a complete skull and lower jaws. Only the snout’s top, the neck base, forelimbs along with the tail-end are absent. Numerous osteoderms were discovered as part of the skeleton, with many mostly in their original positions. In the 1960s and beyond the fossil was further developed with the help of Ronald Croucher using acid baths to separate bones from the matrix. It was a technique that was developed specifically for Charmouth fossils. When the Charmouth fossils were discovered in 1992 Charig said that one of the blocks had yet been treated, but he passed away before the results were published. Norman had hoped to complete the work was able to reveal some brand new anatomical data in 2004. In addition an updated description, it was not available. In the year 2020, Norman published articles on the skull and postcrania, taking the recent discoveries into consideration. The acid baths, as a result of leakages, seriously damaged the bones’ condition as well as causing further cracks and crumbling.

Other than the neotype, there are other fossils that belong to Scelidosaurus. In 1888, Lydekker catalogued an extensive number of single bones, mostly bone fragments and limbs which were taken through the BMNH from the Norris collection. Owen in 1861, described an additional, incomplete the skeleton of a young animal. It was later placed in the collections belonging to Elizabeth Philpot and today is recorded within the Lyme Regis Museum as a specimen LYMPH 1997.37.4-10. Since it was a large specimen, Owen speculated, in the context of the presumed marine environment and marine lifestyle, that Scelidosaurus could be Ovoviviparous. The small size of the prepubis in this specimen proved to scientists that this process was not the primary pubic structure like some believed and who were unable to accept that the thin pubis that was backward-pointing with the Ornithischia were identical to the forward-pointing larger pubic bone found in the majority of reptile groups. Recently there have been new discoveries discovered at Charmouth but not through commercial quarrying, but through volunteers who are Palaeontologists. In 1968, another partial juvenile skeleton was identified as specimen BMNH R6704 which was previously reported in the year 1959. Geologist James Frederick Jackson (1894-1966) from Charmouth It is part of the slightly younger layer the Stonebarrow Marl Membrane dating to the beginning of Pliensbachian approximately the age of 190 million years. In 1985, Simon Barnsley, David Costain and Peter Langham excavated a partial skull that contained a full facial impression and skull that was later sold at the Bristol Museum where it is identified as a specimen BRSMG CE12785. The specimen CAMSMX.39256 can be found in the Collection of Sedgwick Museum in Cambridge. Some specimens are not described due to their private collections. They include the 3.1 meters (ten feet) long skeleton discovered from David Sole in 2000, possibly one of the largest non-avian dino specimen ever found within the British Isles. All the parts of the skeleton are now recognized. The discoveries made by Sole diverge from neotype with respect to the details of the armour. They could represent a different taxon or indicate sexual dimorphism. In the year 2020, Norman did not believe the existence of this.

Source: Wikipedia