What Do You Mean By Stegosaurus?
Stegosaurus is one of the popular dinosaurs with a plated body type. It belonged to the genus of Stegosauria. It belonged to the Late Jurassic Period that once existed about 159 million to 153 million years ago. Dinosaurs of this genus had armour plates all over their bodies. They were characterized by their upright plates on the surface of their backs. They also had spikes on their tails. The fossils of this genus have been previously found in the western parts of the United States. They have been found in Portugal also. They were found in the Kimmeridgian- to early Tithonian-aged strata. It was discovered that this genus bore a close resemblance to the ankylosaurus. Both had dermal armour. They also had similar features like simple curved rows of small teeth. It is believed that this genus has evolved from the lineage of smaller armoured dinosaurs like the Scutellosaurus and Scelidosaurus just like ankylosaurus.
Discovery of Stegosaurus and Stegosaurus in the Isle
Stegosaurus was originally named by Othniel Charles Marsh in the year of 1877. These dinosaurs were first collected from the remains that were recovered north of Morrison. Soon after the discovery of Stegosaurus, the plate arrangement intrigued the researchers. Four plate arrangements were proposed for the Stegosaurus. According to the interpretation of Marsh, The plates were shingle-like armour. This led to the name of roof-lizard Stegosaurus. The types of Stegosaurus species recognized are S. stenpos, S. ungulatus and S. sulcatus. The fossils of the dinosaurs are extremely rare, that too from the Middle Jurassic. The Isle of Skye in Scotland, UK however preserves a variety of dinosaur records. Stegosaurus was added to the Isle. In the Isle, it is described as a giant lumbering herbivore. These dinosaurs were extremely agile and were capable of causing maximum damage. They could even kill a Carnotaurus with a blow. The baby stegosaurus might not cause much damage, unlike the adults. The dinosaurus stegosaurus however had slow speed besides their immense power. In real life also Stegosaurus used to feed on low-growing vegetation. The plates on the body of the adult stegosaurus and baby stegosaurus were discovered in 1887. The plates followed an alternating pattern on the body of the stegosaurus.
Characteristics
Stegosaurus belonged to the kingdom of Animalia. It is characterized by the phylum Chordata, order- Ornithischia and suborder of Stegosauria. It belongs to the family of Stegosauridae. To describe Stegosaurus the Isle mentions its huge body. Dinosaurs of this genus had huge bodies. These dinosaurs were herbivores by nature. They had four legs. These dinosaurs were extremely distinguishable as they had their characteristic broad upright plates. They also had spikes on their tail tips. These spiked tail tips were used as a self-defence mechanism against predators. Dinosaurs stegosaurus were found to have a low brain-to-body mass ratio along with their short neck and a small head. Dinosaurs stegosaurus were dwarves compared to their contemporaries. The dinosaurs had narrow skulls. In the skeletal system, stegosaurus bones were 27 in number in the vertebral column alone. The vertebral column was present anterior to the sacrum. The number of vertebrae varied in the sacrum. The subadult dinosaurs of the genus had 4. There were around 46 caudal(tail) vertebrae present in the dinosaur Stegosaurus. The dermal plates of the dinosaurs consisted of 17 to 20 separate plates along with flat spines. These plates were not directly attached to the skeleton of the animal. The largest plates could measure 60cm wide and 60 cm tall.
Fossils of Stegosaurus
Fossil studies nowadays play an important role to study morphology as well as the physical structure of an extinct animal or species. Similarly, the Stegosaurus fossil reveals its external morphology as well as bone structure and its arrangements. The Stegosaurus fossil was first discovered in the western United States and Portugal. From the Carbon dating process of these fossils, scientists found that it was dated about 155 to 150 million years ago. Initially, the remains of fossils were scattered and fragmented. Othniel Charles Marsh first reassembled the fragmentary skeleton and tried to explain the posture and plate arrangements of Stegosaurus. Such study of fossils is known as palaeontology. Palaeontology studies of the Stegosaurus fossil revealed its posture, size as well as food habits and habitat of Stegosaurus. Cat-sized Stegosaurus fossils were found in China that gave interesting facts about young stegosaurus. Thus, a fossil study revealed such interesting facts about Stegosaurus.
Triceratops- A Contemporary of Stegosaurus
Triceratops first appeared in the Maastrichtian stage that occurred in the Late Cretaceous period. It is the genus of herbivorous ceratopsid dinosaurs. It is extinct. Triceratops was first documented as well as described by Othniel Charles Marsh. The literal meaning of the word ‘ Triceratops’ is ‘three-horned face’. It was an avian dinosaur. It belonged to the Animalia and Phylum Chordata. It had a bony frill. It had horns on the skull. It was very large. It could be as long as 9 metres and 12 short tons in weight. Although earlier it was believed that the frills and horns were used for defence mechanisms, the modern concept suggests that these features were used for the identification of their species. Courtship and dominance were also displayed. Triceratops had a large skull. Unlike Triceratops Stegosaurus had a narrow skull. The skull of Triceratops also bore a single horn on its snout placed above their nostrils. Triceratops had shorthands and they possessed sturdy builds. The limbs of Triceratops were strong. Triceratops Stegosaurus fed on plants. The triceratops is usually described as herding animals although little evidence is provided about their herding culture. They fed on lower vegetation. They could drop large trees with their strong beaks and horns.
Sophie-The Stegosaurus
The first almost completely found fossil specimen of Stegosaurus is named Sophie. It was kept at London's Natural History Museum in December 2014. It is estimated that this specimen is almost 100 million years old. From the studies and different computed tomography it is assembled and it is found that the specimen was of a young adult Stegosaurus. After assembling all the fragments it is revealed that the specimen is 5.6 m long and 2.9 m tall. The specimen Sophie was discovered in Wyoming. The specimen of Sophie the stegosaurus contains a total of 360 bones which makes it almost 85% intact. The specimen was named after the daughter of the fund manager of acquisition. The plate arrangements and plate structure on its back and its tails are very specific. This specimen is very important in determining the posture as well as other physiological characteristics of the species Stegosaurus.
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Did You Know?
The dinosaurs of the genus Stegosaurus had a brain that is sized as small as a brain. They had unusually small brains. A dinosaur as big as 4-ton used to survive on such a small brain. Palaeontologists had once suggested that the brain of the Stegosaurus was located in its butt. It was suggested that this herbivore genus had a brain somewhere close to the hip. However, the presence of the brain in the butt region was soon rejected.
Stegosaurus used to swallow rocks. These rocks were known as gastroliths. This helped them mash the vegetation consumed by the dinosaurs.
Conclusion
The skull and brain of the Stegosaurus were quite small in size as compared to its huge body. The dinosaurs of this genus had forelimbs that were much shorter than their hindlimbs. These dinosaurs had an arched appearance. They also had short feet which were broad. Palaeontologists earlier suggested that the two parallel rows of plates of Stegosaurus were used for self-defence and protection. Discoveries and examinations however suggest the presence of alternating plates on the backbone. No two plates were found to have the same shape or same size. A hypothesis of thermoregulation was also related to the presence of plates in such an arrangement. The plates contained blood vessels and their alternate arrangement was thus related to thermoregulation. The plates seemed to act as thermoregulators releasing excess body heat. These plates could also have acted as solar panels by being faced towards the sun. Stegosaurus is thus considered as one of the most distinct genus of dinosaurs and they have regained a lot of popularity with their display in many natural history museums.
FAQs on Stegosaurus
1. Briefly Describe the Reproduction and Growth of Stegosaurus.
Ans. The Stegosaurus reproduced sexually. It required a male and a female host for reproduction. The reproductive organs of Stegosaurus were located in the cloaca. For the display of mating, the male partners had black plates on their bodies. The female partner used to lay eggs like many other dinosaurs. The eggs had a calcite structure. They had different layers. The eggs also had pore canals. Many eggs varied in thickness. Scientists suggest that the varying species. The dinosaurs preferred to lay eggs on open land. They used to lay eggs on nests. They could lay eggs on dirt also for warmth necessary for the eggs. Laying eggs on land was preferred as it protected the eggs from predators. Dangers of the aquatic larvae stage were avoided in this way. Also, the risk of drying up of ponds was prevented. A hard shell was eventually formed along with a protective membrane. The stegosaurus used to lay only a handful of eggs instead of numerous eggs. After the embryonic stage was completed, it would follow the three growth stages: sub-adult stage, adult stage I, adult stage II. At the time of hatching the eggs would be around 3kg and a grown-up Stegosaurus could weigh up to 5 tons.
3. Describe the Function of the Plates of Stegosaurus.
Ans. Othniel Charles Marsh had earlier suggested that the plates of Stegosaurus acted as armours for their self-defence and protection against predators. However, since the plates were fragile, the theory of Marsh was refuted by Davitashvili in 1961. He claimed that since these plates were delicate and were not placed properly they could not have been used by Stegosaurus for self-defence. However many other scientists supported the theory of Marsh. Bakker had suggested that the location of the plates on the surface of the bodies of The Stegosaurus impeded predators to attack them. Stegosaurus could flip the osteoderms so that an array of spikes were presented before the predators. Another function of plates that was suggested for Stegosaurus was the control of body temperatures. The plates contained blood vessels and their alternate arrangement was thus related to thermoregulation. The blood vessels used to run through the grooves and the air that used to flow between them would cool the blood. Extreme vascularization of the outer layer of bone in Stegosaurus acted as evidence. It was also suggested that these plates helped the animal to increase the absorption of heat from the sun.
3. Describe the Role of Fossil Study in Determining the Posture of Stegosaurus.
Answer. Fossil studies nowadays play an important role to study morphology as well as the physical structure of an extinct animal or species. The study of fossils is known as palaeontology. Palaeontology studies of the Stegosaurus fossil revealed its posture, size as well as food habits and habitat of Stegosaurus. Initially, fossil specimens being fragmented and incomplete it was very difficult to determine the posture of Stegosaurus. With the help of computed tomography Scientists assembled the specimen to determine its proper posture and characteristic features. Scientist Marsh Described Stegosaurus as bipedal due to its short forelimbs. Later it was discarded. It is now confirmed that Stegosaurus are quadrupedal. From the X-Ray of bone specimens, the lower section of the forelimb is shorter than that of the hindlimb. From these morphological characteristics, it can be interpreted that Stegosaurus could not walk very fast and thus they had a maximum speed of 6-7 km/h. Besides this arrangement and structures of plates on the back of the Stegosaurus can be interpreted from fossil studies. From a specimen of car-sized Stegosaurus, it is revealed that young Stegosaurus were toe walkers and they had spikes on their tails.
