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Dinosaur is Greek for "terrible lizard". This is a term that is given to various types of extinct reptiles that were present in the Mesozoic Era that ranged from 230 million to 65 million years before. Dinosaurs were very large reptiles, if not always the largest, to roam around the planet and hence were the most dominant of the creatures at that time. This term was coined as a very formal but zoologic name in the year 1842 by a British anatomist known as Sir Richard Owen. This was done as a reference to the discovery of large fossil bones in southern England. However, this term is used today as an informal association. These reptiles are classified into 2 formal categories which were the orders Ornithischia and Saurischia, contained in the reptile subclass Archosauria. Get dinosaur information from right here.

Thousands of fossils or dinosaur skeleton types have been found all over the world. The earliest findings were attributed to 2 Englishmen for so many years. Gideon Mantell, who was a doctor, made his search in Sussex, England, in 1822. He called it an Iguanodon or "iguana tooth". Also, the Rev. Willam Buckland did his search near Oxford, England. It was known as Megalosaurus or "great lizard". To be honest, some fossil remains were already discovered in the year 1818 at Windsor, Conn., and it was done by Solomon Ellsworth, Jr. These remains were reported as a human then in the publication of the American Journal of Science and Arts for 1820 by Nathan Smith. These remains only got recognition recently as belonging to the Late Triassic/Early Jurassic prosauropod Anchisaurus.

There were many different shapes and sizes of dinosaurs and they had adopted many diverse lifestyles and habitats. This is seen from some of the dinosaur skeleton samples. These samples differed in weight from 2 to 3 kg (4 to 6 lb), which was for the Compsognathus and went up to about 73 metric tons (160,000 lb), which was for Brachiosaurus. Some of the dinosaurs that we know about were pretty large and weighed more than 500 kg (1,100 lb). However, there were a few that weighed less than 45 kg (100 lb). Some dinosaurs were mostly herbivorous, but a few saurischians like theropods were known to be carnivorous. Some dinosaurs were obligate bipeds as they were not able to adopt the four-legged posture, however, there were some four-legged creatures as well. A few of the others were known as facultative bipeds and they were completely able to walk on occasion on their hind legs. Our notes help in getting dinosaur information.

Types of Dinosaurs: Saurischia and Ornithischia

There were two different types of dinosaurs as classified by scientists.

Saurischia: Dinosaur Classification

The order of Saurischia includes 2 different types of dinosaurs: the carnivores come under the suborder Theropoda. Also, there are the large herbivores along with their ancestors that belong to the suborder Sauropodomorpha. Apart from the pelvic arrangement in saurischian order, these two suborders had some anatomical characteristics in common.

The theropods have traditionally been categorized into 2 groups, coelurosaurs who are the small and lightly built dinosaurs and the carnosaurs that were large and heavily built. Some pieces of proof show that this categorisation may not be able to accurately exhibit evolutionary relationships that existed amongst the theropods. So, some scientists also prefer to sort them into certain primitive (belonging to order Ceratosauria) and advanced ( belonging to Tetanurae) categories. Our notes help answer the question of what is a dinosaur.

Theropods were always the types of dinosaurs that had obligate bipeds as they were not able to get a four-legged posture. The rear legs were muscular and had a birdlike foot structure. In some dinosaurs, the rear-limb proportions indicated more running speed. Their forelimbs had sharp and curved claws which could be good for seizing as well as holding their prey. Their long tails have a function as dynamic stabilizers which could be used for counterbalancing. Their head was relatively large to disproportionately bigger, as well as the jaws would usually contain many teeth that were bladelike and filled with serrated edges from front to back. This was clear evidence of their flesh-eating habits. The "ostrich" dinosaur also known as Struthiomimus had some toothless jaws, as we can see from the dinosaur skeleton. These jaws were filled with a birdlike beak. Some of the few scientists have found this as indications that these creatures known as theropods might not have been carnivorous in nature but that is just a thesis.

According to dinosaur history, the smallest theropod that we know of is Compsognathus belonging to the Late Jurassic period in Europe. Also, the largest one is Tyrannosaurus belonging to the Late Cretaceous period in North America, which weighed about 5 or 6 metric tons (about 12,000 lb). That is mostly several thousand times heavier than the Compsognathus that had a height of about 5 m (16 ft), and a length of about 15 m (49 ft). Some other examples include Deinonychus and its cousin the Velociraptor along with the Baryonyx. Theropods were first to appear in the mid-Triassic ages and they mostly thrived until the closing stages of the Cretaceous age, having probably dispersed all over the world. These are some of the types of dinosaurs.

The suborder of Sauropodomorpha consists of two subcategories known as the Sauropoda, which has nearly all of the creatures resembling the known member of their group that was Apatosaurus. The second subcategory was Prosauropoda, who were the more primitive and lesser-known relatives of Sauropoda.

Prosauropods were common during the Late Triassic as well as the Early Jurassic times. They have been discovered on every continent except Australia and Antarctica. There are certain resemblances in their teeth and skulls with the Sauropods but they are otherwise pretty different and have different characteristics such as smaller size ranging from 300 to perhaps 1,500 kg (3,300 lb). These organisms were quadrupedal, but some of them were able to make use of the bipedal posture and their gait. These creatures appeared as herbivores, though they did have teeth like carnivores. This can be found with the skeletal remains of some kinds. One of the best-known examples of prosauropods is Plateosaurus belonging to the Late Triassic period in Europe, according to dinosaur history.

Sauropods were once considered amphibious or semi-aquatic. They included the largest of the dinosaurs. The theory about dinosaurs of these types is often made that they must be mostly dwelling on lakes and swamps. This theory became a hypothesis due to the discovery of limb bones that they had which could be used for supporting the weight of theirs in the water. They also had flexible and longer necks to reach their head to the surface of water to breathe in some air.  But, according to some dinosaur facts, sauropod tracks that were first recognized in Texas in the period of 1930s indicated that these animals were mostly land-dwellers and did not confine themselves to water-covered systems.

The smallest and different types of dinosaurs such as were much larger than elephants, and the largest one - Brachiosaurus (Late Jurassic, East Africa) along with several new, not-named ones were even larger discoveries. These examples are supposed to have a weight of about 73 metric tons (about 160,000 pounds) or even more. Some of the best-known examples are Apatosaurus and Diplodocus belonging to the Late Jurassic period of North America.

Ornithischia: Dinosaur Classification

The Ornithischia are carefully distributed into 4 or 5 different suborders according to dinosaur lover classification, or more commonly known as infraorders and they are also placed under 2 major categories: Cerapoda (Eg: Ornithopoda; Pachycephalosauria, which is included in the suborder of ornithopod by some; as well as Ceratopsia), and Thyreophora (Eg: Stegosauria and Ankylosauria).

Along with some of the traits such as a birdlike pelvis that are common to all of the ornithischians, except some of the very primitive types, they had a proper toothless front part in their mouth that was covered with a horny bill or beak.

The ornithopods were considered to be some of the most successful, diverse, and a unique lot of the ornithischians. They had a worldwide distribution throughout their entire Mesozoic occurrence. The earliest known examples belonged to the Middle and Late Triassic ages (Eg: Pisanosaurus, South America and Heterodontosaurus, Africa). During the end of the Cretaceous period, about 140 million years later, these ornithopods were also the most abundant creatures of all the herbivores. They replaced the sauropods and were considered to be the dominant plant-eaters amongst the dinosaurs. They were capable of having a proper bipedal stance and functional gait. Some were very adept bipeds too. They were also completely able to approach the four-legged posture, and that was mostly their preferred posture for feeding.

A large number of ornithopods, instead exhibited a very functional method of replacement for the tooth to offset their faster rates of tooth wearing. This dental specialization was most highly developed within the Late Cretaceous duck-billed dinosaurs, among which were Corythosaurus and Anatosaurus. It had been this special dental design of the duckbills (and also the ceratopsians) that first led some palaeontologists to take a position about dinosaurian food requirements and possible metabolism. Their grinding dental batteries, consisting of many tightly compacted teeth, are evidence of a high-volume intake of food, probably associated with a high metabolism. Apart from Camptosaurus (Late Jurassic, North America) and Iguanodon (Early Cretaceous, Europe), the duckbills of Asia and North America are best known.

The plated dinosaurs (Stegosauria, of the suborder Thyreophora) were never as important because of the cerapoda. The few fossils found are from Jurassic rocks, mostly from North America, East Africa, and Europe. Like all other ornithischians, stegosaurus were herbivores, but with a little head and few small teeth that appear strangely designed to feed the animal's large body. there's no evidence of the dental specialization seen in other ornithischian kinds. The quality of Stegosaurus was the row of alternating upright bony plates that developed along the rear. Long thought to possess protection in how against predators, these plates were recently shown to possess been highly vascularized and doubtless heavily suffused with blood during life. This has led to the suggestion that they all are cooling limbs, functioning as temperature regulators.

Since then, dinosaur fossils are found everywhere on the planet and studied by palaeontologists to seek out more about the various differing types of those creatures that existed. Scientists have traditionally divided the dinosaur group into two orders: the “bird-hipped” Ornithischia and therefore the “lizard-hipped” Saurischia. From there, dinosaurs are weakened into numerous genera (e.g. Tyrannosaurus or Triceratops) and every genus into one or more species. Some dinosaurs were bipedal, which suggests they walked on two legs. Some walked on four legs (quadrupedal), and a few were ready to switch between these two walking styles. Some dinosaurs were covered with a kind of body armour, and a few probably had feathers, like their modern bird relatives. Some rushed, while others were lumbering and slow. Most dinosaurs were herbivores or plant-eaters, but some were carnivorous and hunted or scavenged other dinosaurs to survive. Students can know more about dinosaurs from all the notes that we have in the best way. This information will definitely be really useful for them.

FAQ (Frequently Asked Questions)

1. Define Theropods.

Ans: Theropods were known as obligate bipeds who were not able to take a four-legged posture. Reliable dinosaur information can be found in our notes.

2. Mention the Classification of the Ornithischia?

Ans: The Ornithischia are carefully distributed into 4 or 5 different suborders, or more commonly known as infraorders and they are also placed under 2 major categories: Cerapoda (Eg: Ornithopoda; Pachycephalosauria, which is included in the suborder of ornithopod by some; as well as Ceratopsia), and Thyreophora (Eg: Stegosauria and Ankylosauria).

3. What are the 2 Groups of Dinosaurs that the Scientists Classified the Organisms Into?

Ans: Dinosaurs are classified into 2 formal categories which were the orders Ornithischia and Saurischia, contained in the reptile subclass Archosauria.