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Stegosaurus

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Stegosaurus

Group Classification

Kingdom Animalia
Phylum Chordata
Class Sauropsida
Superorder Dinosauria
Order Ornithischia
Suborder Thyreophora
Family Stegosauridae

Useful Statistics

Name Stegosaurus
Pronounced Steg-O-Saw-Rus
Diet Herbivore
Size L 30 ft x H 14 ft
Weight 2.8 – 3.2 Tonnes
Period Jurassic
Sub Period Late

Stegosaurus

 

Origin of stegosaurus

Stegosaurus is considered to be one of the commonest forms along with the tyrannosaurus and it is believed to have existed during the late Jurassic era several millions of years ago. The name stegosaurus is derived from its Greek roots ‘stegos’ meaning roof and ‘saurus’ meaning lizard and therefore the stegosaurus is popularly referred to as the ‘roof lizard’.

The stegosaurus belongs to the class of stegosaurid armed dinosaur and is considered to be the largest stegosaurid by the paleontologists. Various historical evidences that have been unearthed reveal that the stegosaurus cohabited about 150 million years ago along with huge sauropods like apatosaurus, camarasaurus and diplodocus. The stegosaurus remains one of the most identifiable variants of the different kinds of dinosaurs because of a unique feature. This refers to the plates on the surface of its body and the tail spikes.

It was recently in the year 2006 that certain fossils belonging to the stegosaurus were unearthed in Portugal and this has given impetus to the belief that the stegosaurus not only lived in the northern part of America but also in Europe.

It is necessary to mention here that initially the very first fossils and relics of the stegosaurus were excavated in the western part of North America in the year 1877 when Othniel Charles Marsh had adopted this name following the discovery in Colorado’s Morrison Formation. However, various evidences collected from this region has also proved that the stegosaurus were a later addition as different other varieties of stegosaurids treaded these regions prior to the stegosaurus.

Taxonomy

There have been classified various different kinds of stegosaurus and most of these variants are divided according to minor differences in their appearances.

Some of the foremost among them include the long spined roof lizard or the stegosaurus longispinus which comprised of four extraordinarily long tail spines and is over 20 ft long. The armored roof lizard or stegosaurus armatus was one of the first of the stegosaurus remains to be unearthed and it measured about 30 ft in length possessing smaller plates and four tail spikes. The most popular variant of the stegosaurus was the stegosaurus stenops or the narrow faced roof lizard which was usually shorter than the stegosaurus armatus in length but had unique skeletal structure.

It had f our tail spikes and several huge and expansive plates on the body. There are also several other species of the stegosaurus which have been discovered from time to time and most of these are still under observation and research and hence not much information is available on them currently. Some of these stegosaurus types include stegosaurus seeleyanus, stegosaurus sulcatus, stegosaurus affinis and stegosaurus ungulatus.

The armored roof lizard or stegosaurus armatus was one of the first of the stegosaurus remains to be unearthed and it measured about 30 ft in length possessing smaller plates and four tail spikes.

Physical Features

The stegosaurus is a large bodied dinosaur though it is nothing compared to the gigantic sauropods and it has distinct physical features. An herbivore having four limbs, the back of the stegosaurus is arched heavily at a particular angle while the tail is static and tough always held high in an upward position without touching the ground.

The stegosaurus measured to about 30 ft in length and the limbs were provided with padded hoofs. The forelimbs had five toes while the hind limbs had three toes. The structuring of the body and also the limbs also go to suggest that these dinosaurs could not move fast and were usually slow wanderers.

The head of the stegosaurus was quite small and insignificant compared to the enormous size of the rest of the body and the positioning of the head as is evident from the fossilized remains of the skull go to prove that they were consumers of the vegetation that grew on the ground. Like all herbivores the stegosaurus too possessed efficient dental arrangement in order to aid the chewing and grinding of food.

Thus the bone structure of the skull and the jaws reveal that the stegosaurus had cheeks where they kept the food while chewing and a set of small triangular, flat teeth aided immensely in grinding the plant matter.

A very interesting fact that has been noted by the scientists with respect to the stegosaurus is that despite their magnanimous body size, their brains were extremely small and it is quite striking to find that while the body weight of the stegosaurus stands close to 5 tons, its brain is worth only 80 grams.

Here again another fascinating discovery with reference to the stegosaurus is the concept of a ‘second brain’. this was pointed out by a renowned scientist that there was a huge passage near the hip region of this dinosaur which could easily house something like a brain and this idea has been popularized by several others who acknowledged the belief that this second brain was essential in organizing and controlling the various functions on the back part of the body of the stegosaurus. However, this idea has been argued as well.

Plates and tail spikes

The most important corporeal features of the stegosaurus however are the plates on its body and the tail spikes which make it stand out among the various dinosaur species. There has been a lot of research regarding the function of these plates and tail spikes and a common consensus has been reached regarding the fact that these spikes and plates were usually used by the stegosaurus for defense purposes.

The stegosaurus comprised of 17 dermal plates shaped like kites having four sides and it should be noted that these were not generated from the bones but rather protruded from the external surface of the skin. These plates are believed to have belonged to a kind of osteoderms which refer to a kind of bony scales on the body and similar bone structures can be observed in most lizards and crocodiles of today.

While these plates have been usually considered as being used for defense purposes against marauders who attacked these herbivores, it can be also be noted that they were not enough to guard the stegosaurus completely as the sides remained exposed to attack. However, the plates also have other functions like it helps to regulate body temperature of the stegosaurus though this fact is also debatable.

The stegosaurus comprised of 17 dermal plates shaped like kites having four sides and it should be noted that these were not generated from the bones but rather protruded from the external surface of the skin.

The stegosaurus possessed about four tail spikes in addition to the 17 dermal plates and these tail spikes were also referred to as thagomizers. The use of the tail spikes have been highly debated from time to time. While a set of evidences do prove that these spikes were indeed used for defense and as a means for protection, it has also been noted that many of the body plates overlapped the vertebrae of the tail thus greatly constraining its movement.

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