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Dinosaurs were the dominant land animals for 160 million years, making them one of the most successful groups of animals ever. The name dinosaur translates as ‘terrible or wondrous lizards’ and they certainly evolved in a diverse range of sizes and shapes, from the gigantic plant-eating sauropods to the quick meat-eating tyrannosaurs. They also sported an impressive array of body modifications including horns, scales and crests. So far, the remains of over 1,000 different dinosaur species have been identified from fossils though technically, birds are feathered dinosaurs, meaning dinosaurs aren’t really extinct at all.

Dinosaurs were given their name by the English paleontologist Richard Owen in 1841.

Scientific name: Dinosauria

Rank: Superorder

Common names: terrible, powerful, wondrous

 

I. Order – Lizard-hipped dinosaurs (Saurischia)

The earliest known dinosaurs, lizard-hipped dinosaurs first appeared in the mid Triassic. As well as these first dinosaurs, the order includes all the carnivorous dinosaurs and one group of herbivores – the sauropods and their close relatives. The name ‘lizard-hipped’ comes from the shape of their pelvis, in which the pubis points towards the front of the animal. Birds are descended from this group of dinosaurs.

Suborder 1- Theropod dinosaurs (Theropoda)

Theropod dinosaurs were the top predators in the Jurassic and Cretaceous periods. For over 100 million years theropods were the only large carnivores on land and included all the infamous carnivorous dinosaurs – Tyrannosaurus, Velociraptor and Spinosaurus. However, not all theropods were predators. Some evolved away from their carnivorous origins to consume an omnivorous or herbivorous diet. Birds are the only living descendants of the theropods.

  • Allosaurus (genus)
  • Australovenator (genus)
  • Tyrannosaurs
  • Carcharodontosaurids
  • Dromaeosaurs
  • Coelophysis (genus)
  • Therizinosaurs
  • Spinosaurus (genus)
  • Epidexipteryx (genus)
  • Gigantoraptor (genus)
  • Abelisaurs

About

Theropoda (theropod /ˈθɛrəpɒd/; suborder name Theropoda /θɨˈrɒpɵdə/, from Greek meaning “beast feet”) is both a suborder of bipedal saurischian dinosaurs, and a clade consisting of that suborder and its descendants (including modern birds). Dinosaurs belonging to the suborder Theropoda were primarily carnivorous, although a number of theropod groups evolved herbivory, omnivory, and insectivory. Theropods first appeared during the Carnian age of the late Triassic period about 230 million years ago (Ma) and included the sole large terrestrial carnivores from the Early Jurassic until at least the close of the Cretaceous, about 65 Ma. In the Jurassic, birds evolved from small specialized coelurosaurian theropods, and are today represented by 9,900 living species.

Among the features linking theropod dinosaurs to birds are the three-toed foot, a furcula (wishbone), air-filled bones, brooding of the eggs, and (in some cases) feathers.

1* Genus – Allosaurus (Allosaurus)

Allosaurus were big, mean killing machines that reigned supreme during the late Jurassic period. They were the most common huge predators in North America 140 million years ago, reaching an impressive 12 metres in length and weighing up to four tonnes. These carnivorous dinosaurs could rip and tear chunks out of the large plant-eating sauropods and stegosaurs of the time. The enormous jaw was filled with long, serrated, back-curving teeth. Near perfect examples of this classic shaped theropod dinosaur were discovered in Wyoming and called Big Al and Big Al Two. Allosaurus fossil remains are extremely rare outside America.

2* Genus – Australovenator (Southern hunter)

Australovenator is the most complete skeleton of a meat-eating dinosaur ever found in Australia. It was described in 2009 as light of weight and built for speed, and placed in a brand new genus of theropod dinosaur. This was Australia’s first really big predator, about six metres long and actually a medium-sized cousin of the Allosaurus. The partial skeleton was found at the bottom of a billabong near the town of Winton, Queensland. Close by was the skeleton of a large sauropod dinosaur. It’s tempting to think that the Australovenator may have been eating the carcass when it got stuck in the mud and couldn’t get out.

 

3* Family – Tyrannosauridae (Tyrant lizards)

The family of tyrannosaurs includes the famous Tyrannosaurus rex as well as other large carnivores such as Albertosaurus and Tarbosaurus. They evolved in the late Cretaceous and their large size made them the top predators of the time. Like human beings, tyrannosaurs went through an adolescent growth spurt, increasing greatly in height and weight until they approached sexual maturity. Thereafter they grew much more slowly until they reached their final size. Tyrannosaur fossils are found in Asia and North America, through their ancestors also lived in Europe.

3.1* Genus – Tarbosaurus (Alarming lizard)

Tarbosaurus was a relative of Tyrannosaurus and lived in Asia during the late Cretaceous. It has the smallest forearms of all the tyrannosaurs known and though slightly smaller than T-rex, was still one of the larger members of the tyrannosaurid family. It had a lightweight skeleton, which probably helped to increase its agility. Tarbosaurus bataar skeletons are common in the rocks of the Nemegt Formation of the Gobi Desert in Mongolia.

3.2* Genus – Tyrannosaurus (T-rex or Tyrant lizard king)

One of the greatest carnivores – though not the largest – ever to have walked the Earth, Tyrannosaurus rex (or T-rex) ruled North America during the late Cretaceous period, some 68-65 million years ago. The massive skull of this mighty theropod dinosaur measured 1.5 metres and was balanced by a long heavy tail. The jaw, filled with huge, saw-edged teeth could deliver a devastating bite. Top predator or mighty scavenger, the ‘tyrant lizard king’ was without doubt a dinosaur to be feared. Thirty specimens have been recovered, some of which (such as those named Sue, Stan and the juvenile Jane!) are almost complete.

3.3* Genus – Daspletosaurus (Frightful lizard)

The name Tyrannosaurus rex or ‘tyrant lizard king’ would have been equally appropriate for Daspletosaurus. This terrifying tyrannosaur preceded T-rex by ten million years, being top of the food chain in North America’s vast flood plains 75 million years ago. A formidable predator, it was nine metres long and weighed as much as three tonnes.

Like the tyrannosaurs that were to follow, it relied on smell and hearing as much as sight. Bite marks in Daspletosaurus skulls suggest they fought each other over food, territory or dominance in a group. A remarkable discovery of a group of Daspletosaurus near some Hadrosaurs raised some interesting questions. Did these tyrannosaurs hunt in packs or come together to feast on the carcasses?

 

4* Family – Carcharodontosauridae (Shark-toothed lizards)

The carcharodontosaurids were a group of giant carnivorous dinosaurs that rivalled and even exceeded Tyrannosaurus in size. Scientists have calculated that one of them, Giganotosaurus, could run at 50 km/h, which is just slower than an ostrich, but 13 km/h faster than a gold medal-winning Olympic sprinter. Carcharodontosaurids were top predators in the ancient continent of Gondwanaland: the area of the world that’s now the southern hemisphere continents – South America, Africa, Antarctica, Australia – and India. They evolved from an Allosaurus-like ancestor and became extinct about 89 million years ago.

4.1* Genus –  Carcharodontosaurus (Jagged-toothed or Sharp-toothed lizard)

Carcharodontosaurus is named after its long sharp teeth with their deadly serrations. It is also known as the ‘shark-toothed’ or ‘jagged-toothed’ lizard. Its teeth would have slashed through flesh with ease, making it one of the most feared and successful meat-eating dinosaurs of North Africa. It was also one of the longest and heaviest, being slightly larger than North America’s Tyrannosaurus rex, although its brain was probably smaller. Two teeth were first identified in Algeria in 1927 and more findings followed in the 1990’s. It is highly likely that Carcharodontosaurus would have come into conflict with the largest carnivorous dinosaur of all time – Spinosaurus. This would have been a battle of epic proportions.

4.2* Genus – Mapusaurus (Earth lizard)

Mapusaurus was a giant South American meat-eating dinosaur with blade-like teeth for slicing off chunks of sauropod flesh. At over ten metres long Mapusaurus was similar in size to the closely related Giganotosaurus. Fossils from at least seven individuals of various ages were discovered in a bone bed in Argentina. This may suggest they worked in groups to take down the large sauropods of the time, such as the colossal Argentinosaurus, something a single Mapusaurus may not have been able to accomplish alone. Alternatively this group find may represent a simple predator-trap.

 

5* Family – Dromaeosauridae (Raptors or Running lizard)

Dromaeosaurs – also called raptors – were carnivorous dinosaurs closely related to birds. Several fossils have been found with evidence of feathers, and many scientists believe that the whole group had an insulating covering of feathers. All dromaeosaurs have a large, sickle-shaped claw on each hind foot, which helped them climb. Small species probably climbed trees, but there is speculation that larger ones used their claws to cling on to prey and as weapons. Dromaeosaur species ranged from about 1.5 to 9 metres long.

5.1* Genus –  Utahraptor (Utah’s robber)

Utahraptor is the largest of the dromaeosaurs, which are also known as raptors. It measured about 6 or 7 metres long and would have weighed more than a polar bear. It had a huge claw on each hind foot which it held clear of the ground as it ran to keep it sharp and ready for action. Its hind limbs were relatively stocky, since it needed power rather than speed to use the deadly claws to kick or cling on to struggling prey. The claws on its hands were also larger and more blade-like than those of other raptors.

5.2* Genus – Velociraptor (Swift seizer)

Velociraptors were made famous in the film ‘Jurassic Park’, though they were a little less impressive in reality, standing not much taller than domestic turkeys. A famous fossil has one locked in battle with a Protoceratops. The predatory Velociraptor had pinned down its plant-eating victim, but both appear to have been overcome, perhaps by a sudden sandstorm. Fossils also show that Velociraptor had large feathers on its forelimbs, perhaps used for display.

5.3* Genus – Microraptor (Small one who seizes)

Microraptor is a small feathered dinosaur with a big story to tell. It is one of the 300 fossils found to date that hint at the evolutionary link between birds and dinosaurs. Its fore and hind legs were covered in long feathers designed for flight. These are true flight feathers as seen in modern birds. Less than a metre long and possessing a claw designed for climbing, Microraptor was at home in the forests of China.

Having climbed high into a tree, Microraptor would only have been capable of gliding from tree to tree by spreading its limbs to form two pairs of rudimentary wings. This ability would have helped it pursue prey or escape an enemy. Microraptor didn’t have things all its own way, however, as its long feathers would have made it clumsy on the ground and therefore vulnerable to predators.

5.4* Genus – Sinornithosaurus (Chinese bird-lizard)

When a perfect specimen of Sinornithosaurus, complete with feather impressions was found, it was a turning point in the study of dinosaurs. Detailed analysis showed tiny structures in the feathers almost identical to those of modern birds. Perhaps more amazingly, pigments were found that hinted at colours such as reddish-brown, yellows and black.

Camouflage would have been useful for this metre-long raptor as it hunted the forests of the early Cretaceous Period. Sinornithosaurus was recovered from China’s fossil-rich Yixian formation. It represents one of the earliest and most primitive of the Dromaeosaurs. It is also one of the most bird-like of the feathered dinosaurs ever found. Whether the grooves along the teeth suggest Sinornithosaurus was venomous is still debated.

 

6* Genus – Coelophysis (Hollow form)

Coelophysis were one of the earliest of the meat-eating dinosaurs from the late Triassic period. Analysis of the numerous well-preserved skeletons found in a quarry in New Mexico has suggested that Coelophysis were small, yet fast and agile predators, powered by strong hind limbs and aided by a long, slender tail. The long jaw was filled with typical meat-eater’s teeth: sharp, serrated and blade-like. Small animals would have been hunted by sight as Coelophysis had relatively large eyes. So many skeletons all found together suggests they may have lived or hunted in packs.

 

7* Family – Therizinosauridae (Reaper lizards)

Therizinosaurs are an enigmatic and bizarre-looking family of theropod dinosaurs. Most theropods, such as Tyrannosaurus rex, were meat-eaters , these weren’t they were either herbivores or omnivores. To date most therizinosaur fossils have been found in China and Mongolia, for example Therizinosaurus. However, recent findings from New Mexico and Utah have placed Nothronychus in North America as well.

7.1* Genus – Nothronychus (Slothful claw)

Nothronychus are related to some dinosaurs with ferocious reputations, like the carnivorous tyrannosaurs and allosaurs. But these weren’t meat-eaters at all, they had evolved to eat plants. These enigmatic and bizarre-looking theropod dinosaurs had a pot-belly, long arms and agile hands with impressive 30cm long claws. They could have been used to pull down branches to reach the leaves or strip bark from trees.

The wicked looking claws may also have defended Nothronychus from predators or fend off rivals. Nothronychus was the first member of the therizinosaur family to be found in the Americas. Most of the others, such as Therizinosaurus, have been found in China and Mongolia.

7.2* Genus – Therizinosaurus (Scythe lizard)

Therizinosaurus had huge claws on its forelimbs that measured up to 70cm long, so would have been a fearsome sight. It was originally described from only a few bones discovered in Mongolia which were at first thought to belong to a turtle-like reptile and not a huge theropod dinosaur! As a Therizinosaurus skull has never been found, there is no definitive evidence as to what this clawed beast ate. However, since it had close relatives known to be herbivorous, it’s likely that Therizinosaurus too was a plant-eater. Its terrible claws were probably used to strip bark from trees or fend off predators and rivals.

 

8* Genus – Spinosaurus (Spine lizard)

Spinosaurus may have been the largest meat-eater to walk the Earth. At a jaw-dropping 17m long and weighing up to 20 tonnes, it was even larger than the mighty Tyrannosaurus. The story of this giant killing machine is a recent one. Although bones were found and described between 1912 and 1915 in Egypt, it’s only in the last few years that a skeleton has been reconstructed. It would have been a formidable predator of North Africa’s giant fish 100 million years ago. The long narrow skull is very similar to modern crocodiles and Spinosaurus lived and hunted in water and on land, as crocodiles do today. The most distinguishing feature of this enormous dinosaur were the 1.5m spines running along its back. They formed a sail that could have been used to regulate heat, to deter enemies or to attract potential mates.

 

9* Genus- Epidexipteryx (Display feather)

For many reasons Epidexipteryx is a remarkable little dinosaur. A single, well preserved, pigeon-sized skeleton was found in China’s fossil-rich Daohugou area and revealed to the world in 2008. Epidexipteryx had four long ribbon-like display feathers on its tail, almost certainly used to attract a mate or threaten an enemy.

Being covered in short, simple body feathers to keep warm Epidexipteryx lacked the flight feathers seen in other bird-like dinosaurs. This strongly suggests that feathers were used for ornamentation long before flight. Epidexipteryx lived between 152 and 168 million years ago, in the mid to late Jurassic Period. Many of its other features suggest a life in the trees hunting insects, safely away from hungry predators on the ground.

 

10* Genus- Gigantoraptor (Gigantic seizer)

In 2005, a Chinese palaeontologist filming sauropod bones in Mongolia came across an unidentified thigh bone. It was a fortunate discovery. The bone belonged to a creature that may have been eight metres in length and more than two tons in weight. Gigantoraptor, as it was subsequently named, is the largest feathered dinosaur discovered to date.

It is 35 times bigger than the next largest species of Oviraptorid. The toothless skull of this bird-like dinosaur was more than half a metre long with a horny beak. It had long hind legs and large claws and would have been fast enough to outrun most predators around 70 million years ago. It seems certain that Gigantoraptor’s feathers were for display rather than for flight or insulation.

 

11* Family- Abelisauridae (Abel’s lizards)

Abelisaurs were the top predators of their time replacing the earlier carcharodontosaurs. They ruled the southern hemisphere, while the mighty tyrannosaurs reigned in the north. Not as big as the tyrannosaurs they were still a force to be reckoned with. These giant killers would have torn flesh from the local sauropods, or even each other, as Majungasaurus did.

Skulls have been found with some interesting ornamentations including bony crests and horns above the eyes, pits and grooves. These were possibly for the purposes of display. The forelimbs of abelisaurs such as Carnotaurus were short and may not have been used. Fossils from this family of theropod dinosaur have, so far, only been found in South America, Africa and the Indian Subcontinent.

 

Suborder 2- Sauropodomorph dinosaurs (Sauropodomorpha)

Sauropods are among the most famous and recognisable dinosaurs: long-necked, long-tailed giants that include Diplodocus and Brachiosaurus. Early sauropods were bipedal and quite small compared to their later descendants which became the heaviest and longest dinosaurs. It requires a four-legged stance to get to truly giant size, as you need to spread your weight. Like elephants today, the largest sauropods could only move at a walk as their leg bones couldn’t withstand the impact of trotting or galloping gaits. However, just because they were restricted to walking didn’t mean they couldn’t put on a turn of speed: their top walking speed has been estimated at between 20 and 35 km/h.

Infraorder 1- Sauropod dinosaurs (Sauropoda)

Described as ‘feats of engineering’, the largest sauropod dinosaurs weighed close to 100 tonnes – ten times the record weight of a modern elephant. Sauropods therefore include the largest land animals ever to have lived. They were a very successful herbivorous group, arising in the early Jurassic and surviving for around 100 million years. Fossil footprints show that sauropod dinosaurs travelled in herds. Notable sauropods include Diplodocus, Apatosaurus (formerly Brontosaurus) and the record-breaking heavyweight Argentinosaurus.

Family- Diplodocid dinosaurs (Diplodocidae)

Diplodocids were a family of giant sauropod dinosaurs. They had shorter legs and longer necks and tails than the other types of sauropod, but were still massive beasts, weighing several times more than African elephants. Despite being herbivores, their teeth were unsuited to chewing plant matter, so – like today’s chickens – they swallowed stones to grind the food in the stomach. Unlike chickens, being 30 metres long they had to select rather large stones for this to be effective. It’s thought that they may have used their long necks for reaching down to feed on the ground, rather than for reaching up into the crown of trees as giraffes do.

Genus 1- Diplodocus (Double beam)

Diplodocus was one of the longest animals to have lived on Earth and may have reached over 30 metres and weighed around 15 tonnes. The quantity of plant material eaten by roaming herds of this massive herbivore is unimaginable. Once the most famous dinosaur in the world, Diplodocus had four large sturdy legs supporting a long neck and a long tail that could be flailed around like a whip. Several different species have been described since the first Diplodocus discovery was made in North America in 1877. They lived there about 150 million years ago during the late Jurassic period.

Genus 2-  Apatosaurus (Deceptive lizard)

Apatosaurus used to be known as brontosaurus, following a labelling error on a very similar specimen. Subsequently renamed, Apatosaurus was one of the larger sauropod dinosaurs, and therefore one of the largest animals ever to have walked the Earth. Peg-like teeth effectively stripped leaves from trees, but were no use for chewing, so Apatosaurus probably swallowed stones to grind up its meals in the gizzard. Enormous size, herding behaviour and a whip-like tail would all have provided valuable defence against the meat-eaters of the time.

 

II. Order- Bird-hipped dinosaurs (Ornithischia)

Bird-hipped dinosaurs derive their name from the shape of their pelvis, which resembles that of modern birds, whose pubis points to the rear of the animal. Unexpectedly, birds did not evolve from these dinosaurs, but from the lizard-hipped dinosaurs, since this shape of pelvis has evolved more than once. Another distinguishing characteristic of the bird-hipped dinosaurs was a horny beak, which they used to crop plants, much like a horse or deer uses its front teeth today. Duck-billed dinosaurs, horned dinosaurs and armoured dinosaurs were all of the bird-hipped variety.

Suborder- Ceropoda (Horn foot)

Ceropod dinosaurs were all plant-eaters and include the horned and duck-billed dinosaurs. The secret of their success was in their teeth. These were much more efficient at grinding up plant food than your typical dinosaur’s dentition, so cerapods were able to extract more nutritional value from their food and tackle plants that others found too tough to digest. It wasn’t until big herbivorous mammals evolved that such efficient chewing teeth were seen again on Earth.

Infraorder 1- Ceratopsia (Horned dinosaurs)

Speculation continues over the function of the wicked looking horns and grand neck frill of the larger ceratopsians such as Triceratops. Were they for protection, display or even to control body temperature? The earliest horned dinosaurs were quite small and got about on two legs. The four legged giants that characterise the group came later. Fossil evidence suggests horned dinosaurs originated in what’s now Asia during the Cretaceous period, spreading out and thriving as herbivores. Many of the species are recognised from their skulls, which seem to be the part of a ceratopsian skeleton most likely to be preserved.

1* Genus-  Triceratops (Three-hornedface)

Together with the bony frill behind its extraordinarily large head, the three distinctive horns of the Triceratops were traditionally viewed as defensive weapons for this mighty herbivore. However, it is likely that they were used in courtship and dominance displays, much as modern deer use their antlers. One of the last groups of dinosaur to evolve, Triceratops would have shared the landscape with, and been preyed upon by, the awesome Tyrannosaurus. There is little evidence that they ever had the spectacular battles so often depicted, however. No complete Triceratops skeleton has yet been found and what was thought to be another horned dinosaur, Torosaurus, has recently been identified as the fully mature form of Triceratops.

2* Genus- Protoceratops (First hornface)

Were the beak and clawed legs of Protoceratops fossil remains the origin of the lion bodied, eagle headed griffin of Greek legend? We know now that Protoceratops was an early type of horned dinosaur related to Triceratops. These herbivores would have been about the size of sheep and may have roamed in herds, devouring the vegetation of the time. Certainly, the finding of fossilised remains of many individuals in one place suggested herd behaviour. One of the two recognised finds of Protoceratops fossils was infamous for having a velociraptor skeleton wrapped around it as if locked in battle.

Infraorder 2- Ornithopoda (Bird feet)

With some of the most advanced chewing apparatus ever developed by a reptile, ornithopod dinosaurs became a most successful group of herbivorous dinosaurs. They rapidly became a prominent feature on North America’s Cretaceous landscape, until they were wiped out by the famous Cretaceous-Tertiary, or K-T, extinction event. Early ornithopods were only about a metre long and could probably run very fast on their hind legs. They evolved to become as large as some of the mighty sauropods, walking and grazing on all four legs, but still using the hind legs for running and reaching up into trees. Notable ornithopods include the duck-billed hadrosaurs and, of course, iguanodon.

1*Genus-  Iguanodons (Iguana tooth)

Plant-eating Iguanodons were large dinosaurs capable of walking on two legs or on all four. Their outstanding feature was a highly specialised, five-fingered hand made up of an erect and spiked thumb used for defence or perhaps foraging, three middle fingers and a grasping fifth finger. Iguanodons were one of the first dinosaurs ever described and artistic impressions have changed much with each new discovery. Currently, it’s thought they held the head low to the ground and their long, heavy tail in the air for balance rather than vice versa. Herds of Iguanodon – the different species varying in size – flourished in Europe and North America during the lower Cretaceous period.

2* Family- Hadrosauridae  (Duck-billed dinosaurs or Bulky lizards)

Duck-billed dinosaurs were successful and common herbivores from the upper Cretaceous period. The secret of their success perhaps lay with the duck-shaped bill that clipped vegetation and the many small teeth that ground it down. There were two types: some with a bony crest on their head for resonating sound and some without. Fossilised nest sites have shown that some species may have travelled to communal nesting grounds to lay eggs, as many bird species do today. Fossils from the many species are found all over modern-day Europe, Asia and North America, and show that some grew to around 12 metres.

3* Genus- Leaellynasaura (Leaellyn’s lizard)

The tail of the small, plant-eating Leaellynasaura dinosaur was three times as long as its body. Described in 1989 after skull fragments and bones were found in Australia’s Dinosaur Cove – one of the few dinosaurs ever found in Australia – they were named after the discoverer’s daughter (Leallyn). Large eye sockets and optic nerve casings may have given leaellynasaura enhanced vision to cope with the long, dark winter months. Odd to think of Australia having such winters, but during the early Cretaceous some 110 million years ago, this part of the world fell within the Antarctic circle.

4* Genus- Muttaburrasaurus (Muttaburra lizard)

A relative of Iguanodon, Muttaburrasaurus had the same spiked thumb and ability to walk either on all fours or on its hind legs. However, it differed in that it may have eaten meat as well as plants. Its name comes from the Australian town where it was first discovered. Muttaburrasaurus had an unusual rounded muzzle with a hollow chamber inside it the purpose of which is unknown. Perhaps it was to improve the sense of smell or to resonate sound and enable Muttaburrasaurus to make loud cries.

Suborder- Thyreophora (Armoured dinosaurs or Shield bearers)

While early armoured dinosaurs had bony scutes like crocodiles, later forms took armour to the extremes, evolving large plates, spikes, clubs and carapaces. Covering yourself in heavy armour proved to be a very successful anti-predation strategy, as armoured dinosaurs evolved during the early Jurassic and lasted right up until the mass extinction at the end of the Cretaceous period. Though there were many variations and modifications within each type, they came in two basic forms: the stegosaurs with their rows of spikes or plates along the spine, and the more heavily amoured ankylosaurs.

1*Genus- Stegosaurus (Roof lizard)

Although nowhere near the largest of the Jurassic dinosaurs, Stegosaurus were still about the size of a bus. Distinctive and heavily built, they were herbivores with short forelimbs and would have walked with their small head close to the ground and the four-spiked tail held high. The double row of plates running along the back helped control body temperature and were probably used in display or possibly in defence against carnivorous Allosaurs. Most fossils for the three known species, including some complete skeletons, have come from the USA, although a recent discovery in Portugal suggests a wider distribution.

Infraorder 1- Ankylosauria (Fused lizards)

Looking like reptilian armadillos, or prehistoric tanks, Ankylosaurs were heavily armoured dinosaurs with protective plates over their head and shoulders. Some species took their protection to extremes and even had armoured eyelids. Spikes and protrusions were common in a bid to deter predators from taking a bite. Some ankylosaurs had a large, heavy club at the end of the tail for wielding as a weapon or, as has also been suggested, for sexual selection. To carry the weight of all this heavy armour, these plant-eating dinosaurs had very short, stout legs.

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