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Dinosaurs and Its Existence
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Dinosaurs and its existence Introduction Are dinosaurs real? This question perhaps clouded the minds of some people. Because although there were a lot of evidences presented still they are lacking and debatable. How dinosaurs live, reproduce and die is the scope of this research. Our group chose this topic because it is interesting and exciting. Reading books and surfing the net about these creatures are like going back into their time. Millions of years ago, giant beasts roamed the earth called dinosaurs. An English scientist named Richard Owen created the word “dinosaur”, which means “fearfully great lizard”. The only proofs of the existence of these beasts were the fossils that were dug up by paleontologists. Fossils are the remains of dead plants and animals that had been preserved in rocks. What are Dinosaurs? What are dinosaurs? Dinosaurs are gigantic creatures that once ruled the earth. They had both the characteristics of birds and reptiles. These creatures varied in different shapes and sizes or even in colors. The only proofs of the existence of these creatures were the fossils that were dug up. They had lived the earth millions of years ago. The Mesozoic was the time where all dinosaurs had lived. Fossils Fossils were the only proof about dinosaurs. Dinosaur bones were first found hundreds of years ago, but people thought they were from giants or dragons. Until Georges Cuvier suggested that they belonged to giant reptiles, in 1882. Then William Buckland name the first dinosaur in 1824, it was named Megalosaurus (big lizard). Then Richard Owen created the word “dinosaur”. Many of us wonder how fossils were formed. When a plant or animal dies it usually rots away. However, if it was buried quickly by sand or mud, parts of it may survive. Moreover, as the time passes by it will turn into a fossil. For example, a dinosaur dies and its flesh rots away. Then layers of mud or sand cover its skeleton. Next, the mud slowly turns to rock and the bones become fossils. As the rock wears away, the fossil is revealed. Mesozoic Eras The Mesozoic was divided into three periods: the Triassic (245-208 Million Years Ago), the Jurassic (208-146 Million Years Ago), and the Cretaceous (146-65 Million Years Ago). Mesozoic means, "Middle Animals”. 2Dinosaurs, which are perhaps the most popular organisms of the Mesozoic, evolved in the Triassic, but were not very diverse until the Jurassic. 3Except for birds, dinosaurs became extinct at the end of the Cretaceous. Triassic The Triassic is the period where the first dinosaurs appeared. 4The Continents were a single land mass called Pangaea (“All-Earth) and dinosaurs could roam all over the world that time. The Ceolophysis, which was 9 feet long, is the perfect example for a dinosaur at this period. Jurassic The Jurassic period was the time were more dinosaurs showed. At this period, Europe and Asia began to move away. The Stegosaurus (“plated lizard”) became widespread during thus period. They are dinosaurs, which had one or two rows of bone plates at its back, and although its body was up to 30 feet in length, its brain was only the size of a walnut. The popular meat-eater at this period was the Allosaurus, which was 30 feet long; it had sharp teeth and curving claws to slash its prey to shreds. Cretaceous In the Cretaceous, the landmasses were separated and different dinosaurs developed on the different continents. However, this was the time when dinosaurs became extinct. The most popular dinosaur, which was a predator, lived in this period. It was Tyrannosaurus Rex or T-Rex (Tyrant Lizard), which was approximately 50 feet long and weighed about 7 tons. Characteristics Dinosaurs were identified according to their bone structure, habitat, coverings, and the kind of food they ate. In terms of their bone structure, they were divided into two groups. The first group was the Ornitischian dinosaurs, which were the “bird-hipped” dinosaurs. Ornitischians were subdivided into four groups, the Stegosaurians or the plated dinosaurs, the Armored Dinosaurs or the dinosaurs that had armors on their body, the Ceratopsians or the horned dinosaurs and the Ornithopods or the duck-billed dinosaurs. The second group was the Saurischian dinosaurs, which were the “lizard hipped dinosaurs. Saurischians were subdivided into two groups, the Sauropods or “lizard feet” dinosaurs, they are biggest dinosaurs among all of the other dinosaurs and the Theropods or “beast feet” dinosaurs, they were dinosaurs who walk upright on their back legs and they only eat meat. In terms of habitat, most dinosaurs lived on land and like animals today some dinosaurs lived in the sea and air. In terms of coverings, some dinosaurs had scales; most land and sea dinosaurs had scales. Others had feathers; there were only a few flying dinosaurs that had feathers and you might not know some land dinosaurs had feathers. Others had fur, the only dinosaurs that had fur are only a few flying dinosaurs. Base on what dinosaurs eat they were only grouped into two the plant eaters and the meat eaters. Most dinosaurs eat plants this from the small two legged dinosaurs to the huge sauropods. 6Plants hard to digest so, to get enough energy from their food, many spent most of the day eating. Bone Structure Dinosaurs were grouped through their bone structure, which was the main group of dinosaurs. This group was divided into two the ornitischians and the saurischians. Dinosaurs differ in bone structure there are ones that had hipbones similar to birds while others are similar to lizards. Although these dinosaurs belong to the same group, some of them have not met, because they do not belong to the same period. Ornithischian Dinosaurs Ornithiscians were dinosaurs whose hipbones are similar to birds. These dinosaurs were only ponderous vegetarians. Despite of their name they were also reptiles they all shared the reptilian characteristics of cold blood and a relatively feeble brain. This group was subdivided into four: the Stegosaurians, the Armored Dinosaurs, the Ceratopsians and the Ornithopods. Stegosaurians Stegosaurians were dinosaurs, which had plates on their bodies. A perfect example is the Stegosaurus (plated dinosaurs), which weighed twenty tons, had a brain about as big as a walnut although its body was up to 30 feet. These dinosaurs became widespread in the Jurassic period. 7It had one or two rows of upright, bony plates along its backbone. 8A blow from its tail could seriously injure, or even kill, an attacker. Armored Dinosaurs Perhaps these dinosaurs were very special, they were the ones who have special characteristics of having an armor-like skin. The most popular one of this group was the plant-eating Ankylosaurus. It protected itself with armor-like skin and bony spikes and was the size of a tank. 9If attacked, it crouched down to protect its soft belly and lashed out with the bony club on the end of its tail. Ceratopsians Ceratopsians were perhaps the bravest dinosaurs among them. They were plant-eating dinosaurs; they developed horns and bony frills to protect themselves. 10They may have charged at enemies like a rhinoceros, or maybe rival males fought by locking horns. Early members of this group were small creatures, only five to six feet long, which had almost small horns and only small neck frills. 11Later types were as large as elephants and had huge horns and flaring collars. Ornithopods Ornithopods were duck-billed dinosaurs and some of them had webbed feet similar to a duck. 12Most duck-billed dinosaurs were about 20 feet long and stood about 15 feet high. 13Some were powerful swimmers and had flattened tails used to propel themselves through the water. Others had as many 2000 teeth in their duck-like bills; some had long crests containing air-storage passages so that they can breathe under water. Examples of them were the Trachodon and the Lambeosaurus. Saurischian Dinosaurs Saurischians were dinosaurs whose hipbones are similar to lizards. In this group, the gigantic plant eaters belonged and including all fierce meat eaters. This group was subdivided into two: the Sauropods and the Theropods. Sauropods Sauropods were the “lizard footed” dinosaurs. They were all plant eaters and walked on four legs. An example is the Brontosaurus meaning, “thunder lizard”. These dinosaurs had huge legs, slender head with long neck and tail, which weighed more than 30 tons. Other examples were the Brachiosaurus and Diplodocus, which are more than 25 feet high and weighed more than 100 tons. Theropods Theropods were the “beast footed” lizards. These dinosaurs were meat eaters that walked upright on their back legs with very small front limbs. 14They walked in two legs and their three toes were armed with sharp claws. Some were fierce hunters, chasing and killing their preys while others were scavengers, feeding on dead animals or snatch eggs. The Tyrannosaurus rex and the Allosaurus are only a few examples of this group. Habitat Like the animals today dinosaurs filled the three main parts of the world: land, water, and air. Most dinosaurs lived on land, some on the sea and few in the air. As we all know a lot of dinosaurs strived on land, they had legs that enables them to walk, run or hunt. Dinosaurs that lived on the sea were somehow like dolphins or sharks while others had webbed feet and were amphibious. In the air, all dinosaurs had wings and can fly but most of them had no feathers instead they had furs. Land Dinosaurs that lived on land mostly eat plants a few fed on meat. They strived like the animals that lived in the jungle. They had a very well food chain, from the producers then to the plant eaters up to the fierce meat eaters. Examples of land dinosaurs were the Tyrannosaurus rex, Allosaurus, Stegosaurus, Brontosaurus, Stegosaurus, Ankylosaurus, Trachodon and many more. Another example was the Scolosaurus, which had a flexible body covering of bone plates separated by softer skin. Sea While dinosaurs ruled on land, other giant reptiles ruled the seas. Most of them were fierce meat eaters; they fed on fishes and other sea creatures. Examples were the pliosaur Kronosaurus, which was which was almost 43 feet long with a huge head. The Plesiosaurus which was 10 feet long with a narrow head and slender neck and tail; two pairs of large, equal-sized paddles; numerous pointed, slightly curved teeth; and fed on fish and the Elasmosaurus, which was 46 feet long with a neck up to 20 feet and a narrow headed creature that fed on fish. There were also prehistoric reptiles that happen to be a relative of modern reptiles. Examples are the Deinosuchus, which was a 40 feet long crocodile and the Archelon, which was 10 feet long with huge front paddles, powered it through the water at up to 15 kilometers per hour. Air When dinosaurs took over the land, others took to the air. 15Fossil evidence shows that some pterosaurs were covered with fur, which probably means they were warm blooded like birds. They had big brains with large areas to control balance and sight. Most of them fed on fish while others snapped on insects. An example is the Quetzalcoatlus, which was the biggest. It had a human-sized body and a wingspan over 30 feet. Another example is the Rhamphorhynchus, which was only the size of a crow with a wingspan of only 40 centimeters. Coverings Dinosaurs had three types of coverings, some had scales, a few had feathers and others had fur. Almost all land dinosaurs and sea dinosaurs had scales having the reptilian characteristic of modern reptiles. Only a few dinosaurs had feathers, it is only the Archaeopteryx and a theropod. Almost all of the flying dinosaurs had furry bodies from the small Rhamphorhynchus to the huge Quetzalcoatlus. Coverings may vary according where dinosaurs lived and what did they eat, but a few dinosaurs had coverings that cannot be explained why. Maybe dinosaurs used their coverings to protect themselves or to attract a mate. Scales Most dinosaurs had scales from the small to the large ones including those that lived in the seas. There were fossils that have been dug up that prove that dinosaurs had scales. However, nobody knows what are the colors of these coverings and what are its uses. Maybe dinosaurs used them for camouflage to hide from enemies or for mating. Fossils of dinosaurs had skin covered with lumps and bumps for protection. 16Several colorful reptiles today have similar skins, so some experts think dinosaurs were also brightly colored. An example is the Ostrich-size Struthiomimus, which was perhaps the fastest dinosaur that could run a speed of 50 kilometers per hour. Another example is the Paralosaurus, which was perhaps that the male had bright colors to attract a female or to warn off other males and the female had dull and drab colors so they are less easy to spot when sitting on eggs or looking after babies Feathers People might not know that some dinosaurs had feathers as their coverings. 17Feathers may have originally evolved for insulation and then been co-opted into flight. The perfect example was the half bird-half reptile, the Archaeopteryx lithographica. It has long been accepted that Archaeopteryx was a transitional form between birds and reptiles, and that it was the earliest known bird in history. 18Unlike all living birds, Archaeopteryx had a full set of teeth, a rather flat sternum ("breastbone"), a long, bony tail, gastralia ("belly ribs"), and three claws on the wing, which could have still been used to grasp prey (or maybe trees). Another example was the specimen found on Liaoning, province of China demonstrates exceptional preservation of structures similar to primitive feathers. This was a Theropod dinosaur that have been found from deposits roughly 130 million years ago during the Late Jurassic, however none have been as well preserved as this new specimen from the Yixian Formation. 19The entire skeleton was preserved on two counter slabs, in a pose much like that of its close relative the oldest bird (Archaeopteryx lithographica) from the Jurassic of Germany. However, it is still a mystery why did this dinosaur had feathers and what were its uses during the time it lived. Fur Perhaps people have thought that the family of flying reptiles or the family of Pterosaurs had feathers but they had fur instead. 20Pterosaurs had furry not feathered bodies and their wings were made from sheets of leathery skin. Fossils had shown that there were Pterosaurs had fur, which means they were probably warm-blooded. Examples were the Quetzalcoatlus, Rhamphorhynchus, Ornithicheirus and the popular one, the Pteranodon. Food Dinosaurs like animals today also need food to survive; they may be carnivores (meat-eaters) or herbivores (plant-eaters). Dinosaurs perhaps eat like animals today, they may have spent the day eating like the elephants or they may have hunted for meat for their food like lion today. Most dinosaurs were herbivores from the small ones to the gigantic ones. The only carnivores were only the fierce theropods. Plant Eaters Plants were the main diet of almost all dinosaurs such as leaves, pine needles, shoots, pinecones, shrub leaves, ferns and horsetails. If you ever wondered if dinosaurs had ate grasses, well dinosaur did not because grasses did no develop on earth until 25 million years after dinosaurs died out. For your information some dinosaurs did ate small stones. These stones were found in the rib cages of many dinosaurs. There were dinosaurs that could move their jaws from side to side, so they could not chew their food. They swallowed it whole and probably swallowed small stones (gastroliths) to help them grind food as chickens swallow grit to do the same thing. Dinosaurs like some sauropods such as the Shunosaurus used their simple peg-like teeth to munch on leaves, pine needles and juicy shoots. A hadrosaur such as the Saurolophus ate leaves from flowering plants and crunchy pinecones; it uses its horny beak then chewed them with its flat back teeth. 21Like the giraffe, Brachiosaurus used its long neck to graze on leafy treetops. Like also the elephants it may almost spent the day eating. Meat Eaters All meat-eating dinosaurs were theropods. They were dinosaurs that walked with two legs and armed with sharp claws. Some were fierce hunters, others were scavengers that fed on dead animals and some just snatched eggs. Some dinosaurs like the Deinonychus (“terrible claw”) and its relatives were specialized in using their claws to kill animals larger than themselves. Its deadly claw was 12 centimeters long located second of its back foot was used for slashing its victims. 22Experts believe that dinosaurs such as Baryonyx snapped up fish with their long crocodile-like jaws. Baryonyx may also have speared fish with the huge hook-like claw on its front teeth, just as brown bears do today. Many carnivores had good eyesight it may have had forward-facing eyes and good binocular (overlapping) vision like modern owls. 23This would have given it a single view of its prey and helped it judge distances. Preservation of Life Survival is the main instinct of animals including dinosaurs. Most dinosaurs laid eggs from the ones who ruled the land, traveled the seas and navigated the air. However, it is still a mystery on how they reproduce, a scientist said that it is hard to identify how fossilized creatures reproduce. We still do not know how dinosaurs took care of their young ones, if they care for them until they are old enough to take care of themselves or after they just hatched, they leave it alone to survive. Reproduction Dinosaurs may have had reproduced like crocodiles or birds, no one is sure how dinosaurs reproduced if they had had sex like animals today for it is hard to identify how fossilized creatures like dinosaurs reproduce. 24A dinosaur specimen was discovered in China's Jiangxi Province, a few hundred miles north of Hong Kong. This was the first time shelled eggs have been found inside a mother dinosaur. The eggs were as looking like pineapple-size potatoes and were much more elongated," The eggs measured lengthwise, the eggs are each 7.9 inches (20 centimeters) in diameter. They measure 2.4 to 3.1 inches (6 to 8 centimeters) in diameter at the "waist." pelvis and eggs and concluded that the dinosaur's reproductive anatomy was in some ways like crocodiles but that it produced and laid eggs like modern birds do. 25Like a crocodile, the dinosaur had two ovaries for making eggs and each ovary was connected to a tube called an oviduct, where the eggshell hardened and through which the eggs traveled to the outside world. However, unlike a crocodile—and like a bird—each of the dinosaur's oviducts produced only one egg at a time. Caring of Babies Dinosaurs of course took care of their babies except for some. Dinosaurs build nests such as the Maiasaura. The Maiasaura made nests by making a low mound of mud about 2 meter across then dug out a nest and lined it twigs and leaves. Then they lay their eggs. It laid for about 20 to 25 eggs then it covers it with more plants to keep it warm. It guards it carefully for there were egg-thieves like the Troodon. And the hatchlings used their sharp tooth on their snouts to break out of their shells. Dinosaurs that lived in the air perhaps build nests on high mountains or large trees and have laid their eggs their. Most sea reptiles laid their eggs on land, like the modern turtles today. 26But Ichthyosaurus gave birth to young in the same way as sea mammals like the dolphin do today. When sea dinosaur lay their eggs, they go into land or in the sandy shores and dig up the soil and lay their eggs then covers them and leaves them alone until they hatches. Theories of Extinction Many theories had aroused why dinosaurs died out. The two popular ones are the Meteorite theory and the Climactic Change theory. These are only two among hundreds or maybe even thousands of theories that had formulated by scientists. Meteorite theory This theory is most popular amongst all. This theory states that there was a time that the earth was showered by meteors and suddenly all kinds of dinosaurs disappeared. This was perhaps made because of the huge crater found off the coast of Mexico. This evidence could mean that a meteorite caused the extinction of dinosaurs. Climactic Change Theory This theory states that the earth had to change its surroundings, this was the time that the earth undergone a great change. Perhaps the change had caused the plants to die and this means that the plant eaters may have died out first then the meat eaters. The meat eaters had still food that time for some could eat dead animal or maybe they have hunted their own kind. Alternatively, maybe they all have died out slowly for none of them took the change of the surroundings. Conclusion Fossils were the only proofs about the existence of dinosaurs. How they lived, reproduced and became extinct could not be explained with utmost certainties. All we have held were their REMAINS. No one had ever seen them. No man could really tell how they exactly looked like. In other words, the concepts we have about dinosaurs were to some extent fabricated and opinionated. Yet, to top them all, there were many accounts sufficient for us to believe that indeed these creatures really existed and had once ruled the earth. Whether they existed during the Mesozoic era was of no importance at all. Biblical account also supported their existence about these seemingly gigantic creatures, which caused lakes and rivers to dry up as they drank. Though indirect the evidences were, interestingly enough, thousands even millions of people were fascinated about dinosaurs irrespective of age. See Also
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