A report on Dinosaur

Birds are avian dinosaurs, and in phylogenetic taxonomy are included in the group Dinosauria.
Triceratops skeleton, Natural History Museum of Los Angeles County
Labeled diagram of a typical archosaur skull, the skull of Dromaeosaurus
Hip joints and hindlimb postures of: (left to right) typical reptiles (sprawling), dinosaurs and mammals (erect), and rauisuchians (pillar-erect)
William Buckland
Sir Richard Owen's coining of the word dinosaur, at a meeting of the British Association for the Advancement of Science in 1841
Paleontologist Robert T. Bakker with mounted skeleton of a tyrannosaurid (Gorgosaurus libratus)
Scipionyx fossil with intestines, Natural History Museum of Milan
The early dinosaurs Herrerasaurus (large), Eoraptor (small) and a Plateosaurus skull, from the Triassic
The supercontinent Pangaea in the early Mesozoic (around 200 million years ago)
Restoration of six dromaeosaurid theropods: from left to right Microraptor, Velociraptor, Austroraptor, Dromaeosaurus, Utahraptor, and Deinonychus
Restoration of four macronarian sauropods: from left to right Camarasaurus, Brachiosaurus, Giraffatitan, and Euhelopus
Restoration of six ornithopods; far left: Camptosaurus, left: Iguanodon, center background: Shantungosaurus, center foreground: Dryosaurus, right: Corythosaurus, far right (large) Tenontosaurus.
Comparative size of Argentinosaurus to the average human
An adult bee hummingbird, the smallest known dinosaur
A nesting ground of the hadrosaur Maiasaura peeblesorum was discovered in 1978
Restoration of two Centrosaurus apertus engaged in intra-specific combat
Restoration of a striking and unusual visual display in a Lambeosaurus magnicristatus
Nest of a plover (Charadrius)
Fossil interpreted as a nesting oviraptorid Citipati at the American Museum of Natural History. Smaller fossil far right showing inside one of the eggs.
This 1897 restoration of Brontosaurus as an aquatic, tail-dragging animal, by Charles R. Knight, typified early views on dinosaur lifestyles.
Comparison between the air sacs of an abelisaur and a bird
Various feathered non-avian dinosaurs, including Archaeopteryx, Anchiornis, Microraptor and Zhenyuanlong
Pneumatopores on the left ilium of Aerosteon riocoloradensis
The Chicxulub Crater at the tip of the Yucatán Peninsula; the impactor that formed this crater may have caused the dinosaur extinction.
Outdated Iguanodon statues created by Benjamin Waterhouse Hawkins for the Crystal Palace Park in 1853
The battles that may have occurred between Tyrannosaurus and Triceratops are a recurring theme in popular science and dinosaurs' depiction in culture
Scale diagram comparing the average human to the longest known dinosaurs in five major clades:Sauropoda (Supersaurus vivianae)Ornithopoda (Shantungosaurus giganteus)Theropoda (Spinosaurus aegyptiacus)
Thyreophora (Stegosaurus ungulatus)
Marginocephalia (Triceratops prorsus)

Dinosaurs are a diverse group of reptiles of the clade Dinosauria.

- Dinosaur

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Overall

Theropoda

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Specimen of the troodontid Jinfengopteryx elegans, with seeds preserved in the stomach region
Fossil of an Anchiornis, showing large preserved feather imprints
Size comparison of selected giant theropod dinosaurs – the largest (left) is Spinosaurus aegyptiacus, smallest (right) is Carcharodontosaurus saharicus.
An ostrich walking on a road in Etosha National Park, Namibia
Mummified enantiornithean wing (of an unknown genus) from Cenomanian amber from Myanmar
Diagram of Deinonychus (left) and Archaeopteryx (right) forelimbs illustrating wing-like posture
Possible early forms Herrerasaurus (large) and Eoraptor (small)
Othniel Charles Marsh, who coined the name Theropoda. Photo c. 1870
Allosaurus was one of the first dinosaurs classified as a theropod.
Ceratosaurus, a ceratosaurid
Irritator, a spinosaurid
Mapusaurus, a carcharodontosaurid
Microraptor, a dromaeosaurid
Passer domesticus, an avian, and the world's most widespread extant wild theropod.

Theropoda, whose members are known as theropods, is a dinosaur clade that is characterized by hollow bones and three-toes and claws on each limb.

Archaeopteryx lithographica is often considered the oldest known true bird.

Bird

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Birds are a group of warm-blooded vertebrates constituting the class Aves, characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweight skeleton.

Birds are a group of warm-blooded vertebrates constituting the class Aves, characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweight skeleton.

Archaeopteryx lithographica is often considered the oldest known true bird.
Anchiornis huxleyi is an important source of information on the early evolution of birds in the Late Jurassic period.
Simplified phylogenetic tree showing the relationship between modern birds and dinosaurs
Confuciusornis sanctus, a Cretaceous bird from China that lived 125 million years ago, is the oldest known bird to have a beak.
Ichthyornis, which lived 93 million years ago, was the first known prehistoric bird relative preserved with teeth.
The range of the house sparrow has expanded dramatically due to human activities.
External anatomy of a bird (example: yellow-wattled lapwing): 1 Beak, 2 Head, 3 Iris, 4 Pupil, 5 Mantle, 6 Lesser coverts, 7 Scapulars, 8 Median coverts, 9 Tertials, 10 Rump, 11 Primaries, 12 Vent, 13 Thigh, 14 Tibio-tarsal articulation, 15 Tarsus, 16 Foot, 17 Tibia, 18 Belly, 19 Flanks, 20 Breast, 21 Throat, 22 Wattle, 23 Eyestripe
Didactic model of an avian heart
The nictitating membrane as it covers the eye of a masked lapwing
The disruptively patterned plumage of the African scops owl allows it to blend in with its surroundings.
Red lory preening
Restless flycatcher in the downstroke of flapping flight
Feeding adaptations in beaks
A flock of Canada geese in V formation
The routes of satellite-tagged bar-tailed godwits migrating north from New Zealand. This species has the longest known non-stop migration of any species, up to 10200 km.
The startling display of the sunbittern mimics a large predator.
Red-billed queleas, the most numerous species of wild bird, form enormous flocks – sometimes tens of thousands strong.
Many birds, like this American flamingo, tuck their head into their back when sleeping.
Like others of its family, the male Raggiana bird-of-paradise has elaborate breeding plumage used to impress females.
Male golden-backed weavers construct elaborate suspended nests out of grass.
Nest of an eastern phoebe that has been parasitised by a brown-headed cowbird
A female calliope hummingbird feeding fully grown chicks
Altricial chicks of a white-breasted woodswallow
Reed warbler raising a common cuckoo, a brood parasite
The peacock tail in flight, the classic example of a Fisherian runaway
Gran Canaria blue chaffinch, an example of a bird highly specialised in its habitat, in this case in the Canarian pine forests
Industrial farming of chickens
The use of cormorants by Asian fishermen is in steep decline but survives in some areas as a tourist attraction.
The 3 of Birds by the Master of the Playing Cards, 15th-century Germany
Painted tiles with design of birds from Qajar dynasty
The California condor once numbered only 22 birds, but conservation measures have raised that to over 500 today.

Birds are feathered theropod dinosaurs and constitute the only known living dinosaurs.

Portrait of Alexandre Brongniart, who coined the term "Jurassic"

Jurassic

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Geologic period and stratigraphic system that spanned from the end of the Triassic Period million years ago to the beginning of the Cretaceous Period, approximately Mya.

Geologic period and stratigraphic system that spanned from the end of the Triassic Period million years ago to the beginning of the Cretaceous Period, approximately Mya.

Portrait of Alexandre Brongniart, who coined the term "Jurassic"
Folded Lower Jurassic limestone layers of the Doldenhorn nappe at Gasteretal, Switzerland
Middle Jurassic strata in Neuquén Province, Argentina
Tidwell Member of the Morrison Formation (Upper Jurassic), Colorado
Base Aalenian GSSP at Fuentelsaz
Pangaea at the start of Jurassic
The breakup of Gondwanaland took place during the Late Jurassic, the Indian Ocean opened up as a result
Formation of the Pacific Plate during the Early Jurassic
Grainstone with calcitic ooids and sparry calcite cement; Carmel Formation, Middle Jurassic, of southern Utah, USA
Petrified Araucaria mirabilis cone from the Middle Jurassic of Argentina
Leaves of Ginkgo huttonii from the Middle Jurassic of England
Sagenopteris phillipsi (Caytoniales) from the Middle Jurassic of Yorkshire, England
Holotype specimen of Platysuchus, a telosaurid thalattosuchian
Thalassemys, a thalassochelydian sea turtle known from the Late Jurassic of Germany
Skeleton of Coeruleodraco
Fossil of Ichthyosaurus somersetensis at the Natural History Museum, London
Rhomaleosaurus cramptoni at the Natural History Museum
Skeleton of Rhamphorhynchus muensteri at Teylers Museum, Haarlem
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Skeleton of Heterodontosaurus, a primitive ornithischian from the Early Jurassic of South Africa
Skeleton of Mamenchisaurus sinocanadorum from the Middle-Late Jurassic of China
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Henkelotherium, a likely arboreal dyolestoid from the Late Jurassic of Portugal
Coelacanth from the Solnhofen Limestone
Head and forefin of Pachycormus, an extinct pachycormiform fish
Fossil of Palaeocarcharias, the oldest known lamniform shark
Lichnomesopsyche daohugouensis, an extinct mesopsychid scorpionfly from the Late Jurassic of China
Mongolarachne from the Late Jurassic of China
Eryon, a polychelidan decapod crustacean from the Late Jurassic of Germany.
Vadasaurus herzogi, a rynchocephalian from the Upper Jurassic Solnhofen Limestone of Germany
Homeosaurus maximiliani, a rynchocephalian from the Solnhofen Limestone
Pleurosaurus,, an aquatic rhynchocephalian from the Late Jurassic of Europe
Eichstaettisaurus schroederi,, an extinct lizard from the Solnhofen Limestone
Skeleton of Ceratosaurus, a ceratosaurid from the Late Jurassic of North America
Skeleton of Monolophosaurus, a basal tetanuran from the Middle Jurassic of China
Restoration of Yi qi, a scansoriopterygid from the Middle to Late Jurassic of China
Fossil of Thrissops, an ichthyodectid stem-group teleost from the Late Jurassic Solnhofen Limestone of Germany, showing preserved colouration
Fossil specimen of Proteroctopus from the Middle Jurassic of France, formerly thought to be worlds oldest known octopus

On land, the fauna transitioned from the Triassic fauna, dominated jointly by dinosauromorph and pseudosuchian archosaurs, to one dominated by dinosaurs alone.

The impact of a meteorite or comet is today widely accepted as the main reason for the Cretaceous–Paleogene extinction event.

Cretaceous

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Geological period that lasted from about 145 to 66 million years ago .

Geological period that lasted from about 145 to 66 million years ago .

The impact of a meteorite or comet is today widely accepted as the main reason for the Cretaceous–Paleogene extinction event.
Drawing of fossil jaws of Mosasaurus hoffmanni, from the Maastrichtian of Dutch Limburg, by Dutch geologist Pieter Harting (1866)
Scipionyx, a theropod dinosaur from the Early Cretaceous of Italy
Map of North America During the Late Cretaceous
A computer-simulated model of surface conditions in Middle Cretaceous, 100 mya, displaying the approximate shoreline and calculated isotherms
Facsimile of a fossil of Archaefructus from the Yixian Formation, China
Derasmosaurus pietraroiae, a rhyncocephalian from the late Early Cretaceous of Italy
Philydrosaurus, a choristodere from the Early Cretaceous of China
Tyrannosaurus rex, one of the largest land predators of all time, lived during the Late Cretaceous
Up to 2 m long and 0.5 m high at the hip, Velociraptor was feathered and roamed the Late Cretaceous
Triceratops, one of the most recognizable genera of the Cretaceous
The azhdarchid Quetzalcoatlus, one of the largest animals to ever fly, lived during the Late Cretaceous
Confuciusornis, a genus of crow-sized birds from the Early Cretaceous
Ichthyornis was a toothed, seabird-like ornithuran from the Late Cretaceous
A scene from the early Cretaceous: a Woolungasaurus is attacked by a Kronosaurus.
Tylosaurus was a large mosasaur, carnivorous marine reptiles that emerged in the late Cretaceous.
Strong-swimming and toothed predatory waterbird Hesperornis roamed late Cretacean oceans.
The ammonite Discoscaphites iris, Owl Creek Formation (Upper Cretaceous), Ripley, Mississippi
A plate with Nematonotus sp., Pseudostacus sp. and a partial Dercetis triqueter, found in Hakel, Lebanon
Cretoxyrhina, one of the largest Cretaceous sharks, attacking a Pteranodon in the Western Interior Seaway
Strong-swimming and toothed predatory waterbird Hesperornis roamed late Cretacean oceans.

These oceans and seas were populated with now-extinct marine reptiles, ammonites, and rudists, while dinosaurs continued to dominate on land.

Sauropoda

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Size comparison of selected giant sauropod dinosaurs
Reconstruction of Ampelosaurus
Some sauropods, such as Alamosaurus sanjuanensis, formed herds segregated by age.
Cast of Toni, a juvenile brachiosaurus (restored as a diplodocid)
Restoration of a rearing Diplodocus by Charles R. Knight, 1911
Mounted skeleton of Barosaurus lentus, depicted in a rearing tripodal stance''
Reconstruction of selected sauropod necks, showing posture and length
Sauropod tracks near Rovereto, Italy
Sauropod footprints
Sauropod tracks at Serras de Aire e Candeeiros Natural Park, Portugal
A sauropod trackway
Reconstructed skeleton used to estimate speed, Museo Municipal Carmen Funes, Plaza Huincul, Argentina
Argentinosaurus - one of the largest dinosaurs known today
The first reconstruction of a sauropod, the skeleton of Camarasaurus supremus. By John A. Ryder, 1877.
Modern reconstructed Camarasaurus skeleton
Several macronarian sauropods; from left to right, Camarasaurus, Brachiosaurus, Giraffatitan, and Euhelopus.

Sauropoda, whose members are known as sauropods (from sauro- + -pod, 'lizard-footed'), is a clade of saurischian ('lizard-hipped') dinosaurs.

Reptiles, from Nouveau Larousse Illustré, 1897–1904, notice the inclusion of amphibians (below the crocodiles)

Reptile

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Reptiles, as most commonly defined, are the animals in the class Reptilia, a paraphyletic grouping comprising all sauropsid amniotes except Aves (birds).

Reptiles, as most commonly defined, are the animals in the class Reptilia, a paraphyletic grouping comprising all sauropsid amniotes except Aves (birds).

Reptiles, from Nouveau Larousse Illustré, 1897–1904, notice the inclusion of amphibians (below the crocodiles)
"Antediluvian monster", a Mosasaurus discovered in a Maastricht limestone quarry, 1770 (contemporary engraving)
The first reptiles had an anapsid type of skull roof, as seen in the Permian genus Captorhinus
Phylogenetic classifications group the traditional "mammal-like reptiles", like this Varanodon, with other synapsids, not with extant reptiles
Bearded dragon (pogona) skeleton on display at the Museum of Osteology
An early reptile Hylonomus
Mesozoic scene showing typical reptilian megafauna: dinosaurs including Europasaurus holgeri, iguanodonts, and Archaeopteryx lithographica perched on the foreground tree stump
Varanus priscus was a giant carnivorous goanna lizard, perhaps as long as 7 metres and weighing up to 1940 kilograms
Skeleton of Champsosaurus, a choristodere, the latest surviving order of extinct reptiles. The last known choristoderes are known from the Miocene, around 11.3 million years ago
Thermographic image of monitor lizards
Juvenile Iguana heart bisected through the ventricle, bisecting the left and right atrium
Sustained energy output (joules) of a typical reptile versus a similar size mammal as a function of core body temperature. The mammal has a much higher peak output, but can only function over a very narrow range of body temperature.
Red-eared slider taking a gulp of air
Skin of a sand lizard, showing squamate reptiles iconic scales
A colubrid snake, Dolichophis jugularis, eating a legless lizard, Pseudopus apodus. Most reptiles are carnivorous, and many primarily eat other reptiles and small mammals.
Gastroliths from a plesiosaur
Common house geckos mating, ventral view with hemipenis inserted in the cloaca
Most reptiles reproduce sexually, for example this Trachylepis maculilabris skink
Reptiles have amniotic eggs with hard or leathery shells, requiring internal fertilization when mating.
A camouflaged Phelsuma deubia on a palm frond
A White-headed dwarf gecko with shed tail
The 1897 painting of fighting "Laelaps" (now Dryptosaurus) by Charles R. Knight
The Rod of Asclepius symbolizes medicine

In particular, the Cretaceous–Paleogene extinction event wiped out the pterosaurs, plesiosaurs, and all non-avian dinosaurs alongside many species of crocodyliforms, and squamates (e.g., mosasaurs).

Discoscaphites iris ammonite from the Owl Creek Formation (Upper Cretaceous), Owl Creek, Ripley, Mississippi

Cretaceous–Paleogene extinction event

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Sudden mass extinction of three-quarters of the plant and animal species on Earth, approximately 66 million years ago.

Sudden mass extinction of three-quarters of the plant and animal species on Earth, approximately 66 million years ago.

Discoscaphites iris ammonite from the Owl Creek Formation (Upper Cretaceous), Owl Creek, Ripley, Mississippi
Rudist bivalves from the Late Cretaceous of the Omani Mountains, United Arab Emirates. Scale bar is 10 mm.
Kronosaurus Hunt, a rendering by Dmitry Bogdanov in 2008. Large marine reptiles, including plesiosaurians such as these, became extinct at the end of the Cretaceous.
Tyrannosaurus was among the dinosaurs living on Earth before the extinction.
Hell Creek Formation
The K–Pg boundary exposure in Trinidad Lake State Park, in the Raton Basin of Colorado, shows an abrupt change from dark- to light-colored rock.
Radar topography reveals the 180 km-wide ring of the Chicxulub crater.
Artistic impression of the asteroid slamming into tropical, shallow seas of the sulfur-rich Yucatán Peninsula in what is today Southeast Mexico. The aftermath of this immense asteroid collision, which occurred approximately 66 million years ago, is believed to have caused the mass extinction of dinosaurs and many other species on Earth. The impact spewed hundreds of billions of tons of sulfur into the atmosphere, producing a worldwide blackout and freezing temperatures which persisted for at least a decade.
The river bed at the Moody Creek Mine, 7 Mile Creek / Waimatuku, Dunollie, New Zealand contains evidence of a devastating event on terrestrial plant communities at the Cretaceous–Paleogene boundary, confirming the severity and global nature of the event.
An artist's rendering of Thescelosaurus shortly after the K–Pg mass extinction. It survived by burrowing, but would soon die of starvation.

A wide range of species perished in the K–Pg extinction, the best-known being the non-avian dinosaurs.

View of the Tethys area during the Ladinian stage

Triassic

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Geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago , to the beginning of the Jurassic Period 201.36 Mya.

Geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago , to the beginning of the Jurassic Period 201.36 Mya.

View of the Tethys area during the Ladinian stage
230 Ma continental reconstruction
Sydney, Australia lies on Triassic shales and sandstones. Almost all of the exposed rocks around Sydney belong to the Triassic Sydney sandstone.
Triassic flora as depicted in Meyers Konversations-Lexikon (1885–90)
Middle Triassic marginal marine sequence, southwestern Utah
Marine vertebrate apex predators of the Early Triassic
Immediately above the Permian–Triassic boundary the glossopteris flora was suddenly largely displaced by an Australia-wide coniferous flora.
Triassic sandstone near Stadtroda, Germany
The mass extinction event is marked by 'End Tr'
Skull of a Triassic Period phytosaur found in the Petrified Forest National Park
Tanystropheus, a long-necked tanystropheid
Proterosuchus, a crocodile-like early archosauriform from the Early Triassic
Staurikosaurus, one of the earliest dinosaurs, a member of the Triassic family Herrerasauridae
Postosuchus, a rauisuchid which was an apex predator in parts of Late Triassic North America
Plateosaurus was one of the largest of early sauropodomorphs, or "prosauropods", of the Late Triassic
Coelophysis was one of the most abundant theropod dinosaurs in the Late Triassic
Lystrosaurus was a widespread dicynodont and the most common land vertebrate during the Early Triassic, after animal life had been greatly diminished
Cynognathus was a carnivorous mammal-like cynodont from the Early Triassic.

A specialized subgroup of archosaurs, called dinosaurs, first appeared in the Late Triassic but did not become dominant until the succeeding Jurassic Period.

Archosaur

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Clade of diapsids, with birds and crocodilians as the only living representatives.

Clade of diapsids, with birds and crocodilians as the only living representatives.

mandibular fenestrae
Examples of pseudosuchians. Clockwise from top-left: Longosuchus meadei (an aetosaur), Gavialis gangeticus (a crocodilian), Saurosuchus galilei (a loricatan), Pedeticosaurus leviseuri (a sphenosuchian), Chenanisuchus lateroculi (a dyrosaurid), and Dakosaurus maximus (a thalattosuchian).
Examples of avemetatarsalians. Clockwise from top-left: Tupuxuara leonardi (a pterosaur), Alamosaurus sanjuanensis, (a sauropod), Tsintaosaurus spinorhinus (an ornithopod), Daspletosaurus torosus (a tyrannosaurid), Pentaceratops sternbergii (a ceratopsian), and Grus grus (a neornithian).
Hip joints and hindlimb postures
Terrestrisuchus
Chirotherium footprint in Triassic sediments

Extinct archosaurs include non-avian dinosaurs, pterosaurs, and extinct relatives of crocodilians.

Pterosaur

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Pterosaurs ( from Greek pteron and sauros, meaning "wing lizard") were flying reptiles of the extinct clade or order Pterosauria.

Pterosaurs ( from Greek pteron and sauros, meaning "wing lizard") were flying reptiles of the extinct clade or order Pterosauria.

Conical tooth, possibly from Coloborhynchus
Reconstruction of crests: three crested tapegyarids. From top to bottom: Tapejara wellnhoferi, Tupandactylus navigans, Tupandactylus imperator (drawn to scale)
The skull of Thalassodromeus
A neck vertebra of Arambourgiania
The neck of Anhanguera was longer than the torso
The shoulder girdle connected to the notarium
Reconstructed wing planform of Quetzalcoatlus northropi (A) compared to the wandering albatross Diomedea exulans (B) and the Andean condor Vultur gryphus (C). These are not to scale; the wingspan of Q. northropi was more than three times as long as that of the wandering albatross.
Some specimens, such as this Rhamphorhynchus, preserve the membrane structure
Sordes, as depicted here, evidences the possibility that pterosaurs had a cruropatagium – a membrane connecting the legs that, unlike the chiropteran uropatagium, leaves the tail free
An anhanguerid pelvis seen from above, with the right side rotated towards the viewer
Sordes preserved pycnofibers
Jeholopterus
Engraving of the original Pterodactylus antiquus specimen by Egid Verhelst II, 1784
Newman's marsupial pterosaurs
Seeley's dynamical Dimorphodon reconstruction
This drawing of Zhejiangopterus by John Conway exemplifies the "new look" of pterosaurs
The three-dimensionally preserved skull of Anhanguera santanae, from the Santana Formation, Brazil
Life restoration of Sharovipteryx, a gliding "protorosaur" which some controversial studies have posited as a close relative of pterosaurs.
Life restoration of Scleromochlus, an archosauromorph theorized to be related to pterosaurs.
Life restoration of Lagerpeton, lagerpetids share many anatomical and neuroanatomical similarities with pterosaurs.
The skeleton of a pterosaur on display in the Arizona Museum of Natural History in Mesa Arizona.
Diagrams showing breathing motion (top two) and internal air sac system (bottom two)
Pterosaur flight adaptations.
Skeletal reconstruction of a quadrupedally launching Pteranodon longiceps
The probable Azhdarchid trace fossil Haenamichnus uhangriensis.
The fossil trackways show that pterosaurs like Hatzegopteryx were quadrupeds, and some rather efficient terrestrial predators.
Fossil pterodactyloid juvenile from the Solnhofen Limestone
Quetzalcoatlus models in South Bank, created by Mark Witton for the Royal Society's 350th anniversary
Scene from When Dinosaurs Ruled the Earth depicting an outsized Rhamphorhynchus

These are possibly 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.