The species Tyrannosaurus rex (rex meaning “king” in Latin), is one of the most well-represented of the large theropods. Tyrannosaurus lived throughout what is now western North America, on what was then an island continent known as Laramidia. Tyrannosaurus had a much wider range than other tyrannosaurids. Fossils are found in a variety of rock formations dating to the Maastrichtian age of the upper Cretaceous Period, 68 to 66 million years ago. It was the last known member of the tyrannosaurids, and among the last non-avian dinosaurs to exist before the Cretaceous–Paleogene extinction event.

Like other tyrannosaurids, Tyrannosaurus was a bipedal carnivore with a massive skull balanced by a long, heavy tail. Relative to its large and powerful hind limbs, Tyrannosaurus forelimbs were short but unusually powerful for their size and had two clawed digits. The most complete specimen measures up to 12.3 m in length though T. rex could grow to lengths of over 12.3 m, up to 3.66 meters tall at the hips, and according to most modern estimates 8.4 metric tons to 14 metric tons in weight.

Although other theropods rivalled or exceeded Tyrannosaurus Rex in size, it is still among the largest known land predators and is estimated to have exerted the strongest bite force among all terrestrial animals. By far the largest carnivore in its environment, Tyrannosaurus Rex was most likely an apex predator, preying upon hadrosaurs, armoured herbivores like ceratopsians and ankylosaurs, and possibly sauropods. Most palaeontologists today accept that Tyrannosaurus was both an active predator and a scavenger. (WIKIPEDIA)

Stegosaurus is a genus of herbivorous dinosaur that dates to the Late Jurassic period, where they are found in strata, between 155 and 150 million years ago, in the western United States and Portugal. Of the species that have been classified in the upper Morrison Formation of the western US, only three are universally recognized; S. stenops, S. ungulatus and S. sulcatus. The remains of over 80 individual animals of this genus have been found. Stegosaurus would have lived alongside dinosaurs such as Apatosaurus, Diplodocus, Brachiosaurus, Allosaurus, and Ceratosaurus; the latter two may have preyed on it.

These were large, heavily built, herbivorous quadrupeds with rounded backs, short fore limbs, long hind limbs, and tails held high in the air. Due to their distinctive combination of broad, upright plates and tail tipped with spikes, Stegosaurus is one of the most recognizable kinds of dinosaurs. The function of this array of plates and spikes has been the subject of much speculation among scientists. Today, it is generally agreed that their spiked tails were most likely used for defense against predators, while their plates may have been used primarily for display, and secondarily for thermoregulatory functions.

Stegosaurus had a relatively low brain-to-body mass ratio. It had a short neck and a small head, meaning it most likely ate low-lying bushes and shrubs. One species, Stegosaurus ungulatus, is the largest known of all the stegosaurians (bigger than related dinosaurs such as Kentrosaurus and Huayangosaurus).

Stegosaurus remains were first identified during the “Bone Wars” by Othniel Charles Marsh at Dinosaur Ridge National Landmark. The first known skeletons were fragmentary and the bones were scattered, and it would be many years before the true appearance of these animals, including their posture and plate arrangement, became well understood. Despite its popularity in books and film, mounted skeletons of Stegosaurus did not become a staple of major natural history museums until the mid-20th century, and many museums have had to assemble composite displays from several different specimens due to a lack of complete skeletons. Stegosaurus is one of the better-known dinosaurs, and has been featured in film, postal stamps, and many other types of media. (WIKIPEDIA)

Pterosaurs were flying reptiles thaty existed during most of the Mesozoic: from the late Triassic to the end of the Cretaceous (228 to 66 million years ago). Pterosaurs are the earliest vertebrates known to have evolved powered flight. Their wings were formed by a membrane of skin, muscle, and other tissues stretching from the ankles to a dramatically lengthened fourth finger.

There were two major types of pterosaurs. Basal pterosaurs were smaller animals with fully toothed jaws and, typically, long tails. Their wide wing membranes probably included and connected the hind legs. On the ground, they would have had an awkward sprawling posture, but their joint anatomy and strong claws would have made them effective climbers, and they may have lived in trees. Basal pterosaurs were insectivores or predators on small vertebrates. Later pterosaurs evolved many sizes, shapes, and lifestyles. Pterodactlyoids had narrower wings with free hind limbs, highly reduced tails, and long necks with large heads. On the ground, pterodactyloids walked well on all four limbs with an upright posture, standing plantigrade on the hind feet and folding the wing finger upward to walk on the three-fingered “hand.” They could take off from the ground, and fossil trackways show at least some species were able to run and wade or swim. Their jaws had horny beaks, and some groups lacked teeth. Some groups developed elaborate head crests with sexual dimorphism.

Pterosaurs sported coats of hair-like filaments known as pycnofibers, which covered their bodies and parts of their wings. Pycnofibers grew in several forms, from simple filaments to branching down feathers. These are homologous to the down feathers found on both avian and some non-avian dinosaurs, suggesting that early feathers evolved in the common ancestor of pterosaurs and dinosaurs, possibly as insulation. In life, pterosaurs would have had smooth or fluffy coats that did not resemble bird feathers. They were warm-blooded active animals. Pterosaurs spanned a wide range of adult sizes, from the very small anurognathids to the largest known flying creatures of all time, including Quetzalcoatlus and Hatzegopteryx, which reached wingspans of at least nine metres. The combination of endothermy, a good oxygen supply and strong muscles allowed pterosaurs to be powerful and capable flyers.

Pterosaurs had a variety of lifestyles. Traditionally seen as fish-eaters, the group is now understood to have included hunters of land animals, insectivores, fruit eaters and even predators of other pterosaurs. They reproduced by means of eggs, some fossils of which have been discovered.(Source:Wikipedia)

Triceratops is a genus of herbivorous ceratopsid dinosaur that first appeared during the late Maastrichtian stage of the late Cretaceous period, about 68 million years ago (mya), in what is now North America. It is one of the last-known non-avian dinosaur genera, and became extinct in the Cretaceous–Paleogene extinction event 66 million years ago. The name Triceratops, which literally means “three-horned face”, is derived from the Ancient Greek words τρί- (tri-) meaning “three”, κέρας (kéras) meaning “horn”, and ὤψ (ōps) meaning “face”.

Triceratops has been documented by numerous remains collected since the genus was first described in 1889 by Othniel Charles Marsh. Specimens representing life stages from hatchling to adult have been found. As the archetypal ceratopsid, Triceratops is one of the most popular dinosaurs, and has been featured in film, postal stamps, and many other types of media.

Bearing a large bony frill and three horns on the skull, and its large four-legged body possessing similarities with the modern rhinoceros, Triceratops is one of the most recognizable of all dinosaurs and the best-known ceratopsid. It was also one of the largest, up to 9 meters long and 12 metric tons in weight. It shared the landscape with and was probably preyed upon by Tyrannosaurus, though it is less certain that the two did battle in the fanciful manner often depicted in museum displays and popular images. The functions of the frills and three distinctive facial horns on its head have long inspired debate. Traditionally, these have been viewed as defensive weapons against predators. More recent interpretations find it probable that these features were primarily used in species identification, courtship and dominance display, much like the antlers and horns of modern ungulates.

Triceratops was traditionally placed within the “short-frilled” ceratopsids but modern cladistic studies show it to be a member of the Chasmosaurinae which usually have long frills. Two species, T. horridus and T. prorsus, are considered valid today, from the seventeen species that have ever been named. Research published in 2010 concluded that the contemporaneous Torosaurus, a ceratopsid long regarded as a separate genus, represents Triceratops in its mature form. This view was immediately disputed with examination of more fossil evidence needed to settle the debate.(WIKIPEDIA)

Brontosaurus (“thunder lizard” from Greek) is a genus of gigantic quadruped sauropod dinosaurs. Although the type species, B. excelsus, had long been considered a species of the closely related Apatosaurus, researchers proposed in 2015 that Brontosaurus is a genus separate from Apatosaurus and that it contains three species: B. excelsus, B. yahnahpin, and B. parvus.

Brontosaurus had a long, thin neck and a small head adapted for a herbivorous lifestyle, a bulky, heavy torso, and a long, whip-like tail. The various species lived during the Late Jurassic epoch, in the Morrison Formation of what is now North America, and were extinct by the end of the Jurassic. Adult individuals of Brontosaurus are estimated to have weighed up to 15 tonnes and measured up to 22 metres long.

Historically, sauropods like Brontosaurus were believed to be too massive to support their own weight on dry land, so theoretically they must have lived partly submerged in water, perhaps in swamps. Recent findings do not support this, and sauropods are thought to have been fully terrestrial animals.

Diplodocids like Brontosaurus are often portrayed with their necks held high up in the air, allowing them to browse on tall trees. Though some studies have suggested that diplodocid necks were less flexible than previously believed, other studies have found that all tetrapods appear to hold their necks at the maximum possible vertical extension when in a normal, alert posture, and argue that the same would hold true for sauropods barring any unknown, unique characteristics that set the soft tissue anatomy of their necks apart from that of other animals. (WIKIPEDIA)