141-587: Ctenochasmatidae is a group of pterosaurs within the suborder Pterodactyloidea . They are characterized by their distinctive teeth, which are thought to have been used for filter-feeding . Ctenochasmatids lived from the Late Jurassic to the Early Cretaceous periods. The earliest known ctenochasmatid remains date to the Late Jurassic Kimmeridgian age. Previously, a fossil jaw recovered from
282-442: A follicle in the skin . The basal part of the calamus is without vanes. This part is embedded within the skin follicle and has an opening at the base (proximal umbilicus) and a small opening on the side (distal umbilicus). Hatchling birds of some species have a special kind of natal down feathers (neossoptiles) which are pushed out when the normal feathers (teleoptiles) emerge. Flight feathers are stiffened so as to work against
423-432: A bird's head, neck and trunk. Filoplumes are entirely absent in ratites . In some passerines, filoplumes arise exposed beyond the pennaceous feathers on the neck. The remiges, or flight feathers of the wing, and rectrices, or flight feathers of the tail, are the most important feathers for flight. A typical vaned feather features a main shaft, called the rachis . Fused to the rachis are a series of branches, or barbs ;
564-402: A cusp covering the rear belly, between the pelvis and the belly ribs. The vertical mobility of this element suggests a function in breathing, compensating the relative rigidity of the chest cavity. The hindlimbs of pterosaurs were strongly built, yet relative to their wingspans smaller than those of birds. They were long in comparison to the torso length. The thighbone was rather straight, with
705-458: A few millimetres thin transversely. The bony crest base would typically be extended by keratinous or other soft tissue. Since the 1990s, new discoveries and a more thorough study of old specimens have shown that crests are far more widespread among pterosaurs than previously assumed. That they were extended by or composed completely of keratin, which does not fossilize easily, had misled earlier research. For Pterorhynchus and Pterodactylus ,
846-411: A flying creature in a letter to Georges Cuvier . Cuvier agreed in 1801, understanding it was an extinct flying reptile. In 1809, he coined the name Ptéro-Dactyle , "wing-finger". This was in 1815 Latinised to Pterodactylus . At first most species were assigned to this genus and ultimately "pterodactyl" was popularly and incorrectly applied to all members of Pterosauria. Today, paleontologists limit
987-449: A large rachis but few barbs. Rictal bristles are found around the eyes and bill. They may serve a similar purpose to eyelashes and vibrissae in mammals . Although there is as yet no clear evidence, it has been suggested that rictal bristles have sensory functions and may help insectivorous birds to capture prey. In one study, willow flycatchers ( Empidonax traillii ) were found to catch insects equally well before and after removal of
1128-445: A limited mobility. These toes were clawed but the claws were smaller than the hand claws. The rare conditions that allowed for the fossilisation of pterosaur remains, sometimes also preserved soft tissues. Modern synchrotron or ultraviolet light photography has revealed many traces not visible to the naked eye. These are often imprecisely called "impressions" but mostly consist of petrifications , natural casts and transformations of
1269-464: A meal. As with fish, the top and bottom colors may be different, in order to provide camouflage during flight. Striking differences in feather patterns and colors are part of the sexual dimorphism of many bird species and are particularly important in the selection of mating pairs. In some cases, there are differences in the UV reflectivity of feathers across sexes even though no differences in color are noted in
1410-559: A means for determining the evolutionary relationships of bird families. Species that incubate their own eggs often lose their feathers on a region of their belly, forming a brooding patch . The colors of feathers are produced by pigments, by microscopic structures that can refract , reflect, or scatter selected wavelengths of light, or by a combination of both. Most feather pigments are melanins (brown and beige pheomelanins , black and grey eumelanins ) and carotenoids (red, yellow, orange); other pigments occur only in certain taxa –
1551-400: 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 (also called 'non-pterodactyloid pterosaurs' or ' rhamphorhynchoids ') were smaller animals with fully toothed jaws and, typically, long tails. Their wide wing membranes probably included and connected the hind legs. On
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#17328873280521692-516: A membrane that stretched between the legs, possibly connecting to or incorporating the tail, called the uropatagium ; the extent of this membrane is not certain, as studies on Sordes seem to suggest that it simply connected the legs but did not involve the tail (rendering it a cruropatagium ). A common interpretation is that non-pterodactyloid pterosaurs had a broader uro/cruropatagium stretched between their long fifth toes, with pterodactyloids, lacking such toes, only having membranes running along
1833-425: A new fossil of Tupandactylus cf. imperator was found to have melanosomes in forms that signal an earlier-than-anticipated development of patterns found in extant feathers. The new specimen suggested that pterosaur integumentary melanosomes exhibited a more complex organization than those previously known from other pterosaurs. This indicates the presence of a unique form of melanosomes within pterosaur integument at
1974-540: A number of industrial applications as a medium for culturing microbes, biodegradable polymers, and production of enzymes. Feather proteins have been tried as an adhesive for wood board. Some groups of Native people in Alaska have used ptarmigan feathers as temper (non-plastic additives) in pottery manufacture since the first millennium BC in order to promote thermal shock resistance and strength. Eagle feathers have great cultural and spiritual value to Native Americans in
2115-462: A pennibrachium (a wing-like structure consisting of elongate feathers), while younger ones did not. This suggests that the pennibrachium was a secondary sex characteristic and likely had a sexual function. Several genes have been found to determine feather development. They will be key to understand the evolution of feathers. For instance, some genes convert scales into feathers or feather-like structures when expressed or induced in bird feet, such as
2256-702: A popular trend as a hairstyle accessory, with feathers formerly used as fishing lures now being used to provide color and style to hair. Feather products manufacturing in Europe has declined in the last 60 years, mainly due to competition from Asia. Feathers have adorned hats at many prestigious events such as weddings and Ladies Day at racecourses (Royal Ascot). The functional view on the evolution of feathers has traditionally focused on insulation, flight and display. Discoveries of non-flying Late Cretaceous feathered dinosaurs in China, however, suggest that flight could not have been
2397-450: A powder puff to apply the powder. Waterproofing can be lost by exposure to emulsifying agents due to human pollution. Feathers can then become waterlogged, causing the bird to sink. It is also very difficult to clean and rescue birds whose feathers have been fouled by oil spills . The feathers of cormorants soak up water and help to reduce buoyancy, thereby allowing the birds to swim submerged. Bristles are stiff, tapering feathers with
2538-436: A role in the evolution of powered flight. The coloration of feathers is believed to have evolved primarily in response to sexual selection . In fossil specimens of the paravian Anchiornis huxleyi and the pterosaur Tupandactylus imperator , the features are so well preserved that the melanosome (pigment cells) structure can be observed. By comparing the shape of the fossil melanosomes to melanosomes from extant birds,
2679-411: A rotation could be caused by an abduction of the thighbone, meaning that the legs would be spread. This would also turn the feet into a vertical position. They then could act as rudders to control yaw. Some specimens show membranes between the toes, allowing them to function as flight control surfaces. The uropatagium or cruropatagium would control pitch. When walking the toes could flex upwards to lift
2820-449: A supraneural plate that, however, would not contact the notarium. The tails of pterosaurs were always rather slender. This means that the caudofemoralis retractor muscle which in most basal Archosauria provides the main propulsive force for the hindlimb, was relatively unimportant. The tail vertebrae were amphicoelous, the vertebral bodies on both ends being concave. Early species had long tails, containing up to fifty caudal vertebrae,
2961-464: A thousand bristle-like teeth. Dsungaripteridae covered their teeth with jawbone tissue for a crushing function. If teeth were present, they were placed in separate tooth sockets. Replacement teeth were generated behind, not below, the older teeth. The public image of pterosaurs is defined by their elaborate head crests. This was influenced by the distinctive backward-pointing crest of the well-known Pteranodon . The main positions of such crests are
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#17328873280523102-416: A unique, complex circulatory system of looping blood vessels. The combination of actinofibrils and muscle layers may have allowed the animal to adjust the wing slackness and camber . As shown by cavities in the wing bones of larger species and soft tissue preserved in at least one specimen, some pterosaurs extended their system of respiratory air sacs into the wing membrane. The pterosaur wing membrane
3243-705: A waste product of poultry farming, including chickens , geese , turkeys , pheasants , and ostriches . These feathers are dyed and manipulated to enhance their appearance, as poultry feathers are naturally often dull in appearance compared to the feathers of wild birds. Feather derives from the Old English "feþer", which is of Germanic origin; related to Dutch "veer" and German "Feder", from an Indo-European root shared by Sanskrit's "patra" meaning 'wing', Latin's "penna" meaning 'feather', and Greek's "pteron", "pterux" meaning 'wing'. Because of feathers being an integral part of quills , which were early pens used for writing,
3384-427: A waterproofing agent and a feather conditioner . Powder down has evolved independently in several taxa and can be found in down as well as in pennaceous feathers. They may be scattered in plumage as in the pigeons and parrots or in localized patches on the breast, belly, or flanks, as in herons and frogmouths. Herons use their bill to break the powder down feathers and to spread them, while cockatoos may use their head as
3525-408: A weight of up to 250 kilograms (550 pounds) for the largest species. Compared to the other vertebrate flying groups, the birds and bats, pterosaur skulls were typically quite large. Most pterosaur skulls had elongated jaws. Their skull bones tend to be fused in adult individuals. Early pterosaurs often had heterodont teeth, varying in build, and some still had teeth in the palate. In later groups
3666-453: A wide range of adult sizes , from the very small anurognathids to the largest known flying creatures, including Quetzalcoatlus and Hatzegopteryx , which reached wingspans of at least nine metres. The combination of endothermy , a good oxygen supply and strong muscles made pterosaurs powerful and capable flyers. Pterosaurs are often referred to by popular media or the general public as "flying dinosaurs", but dinosaurs are defined as
3807-482: A wingspan no less than 25 centimetres (10 inches). The most sizeable forms represent the largest known animals ever to fly, with wingspans of up to 10–11 metres (33–36 feet). Standing, such giants could reach the height of a modern giraffe . Traditionally, it was assumed that pterosaurs were extremely light relative to their size. Later, it was understood that this would imply unrealistically low densities of their soft tissues. Some modern estimates therefore extrapolate
3948-604: Is a stub . You can help Misplaced Pages by expanding it . Pterosaurs Ornithosauria Seeley , 1870 Pterosaurs are an extinct clade of flying reptiles in the order Pterosauria . They 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
4089-402: Is actually more closely related to Ornithischia , to which it formed the sister group within the clade Ornithoscelida . The study also suggested that if the feather-like structures of theropods and ornithischians are of common evolutionary origin then it would be possible that feathers were restricted to Ornithoscelida. If so, then the origin of feathers would have likely occurred as early as
4230-455: Is called plumology (or plumage science ). People use feathers in many ways that are practical, cultural, and religious. Feathers are both soft and excellent at trapping heat ; thus, they are sometimes used in high-class bedding , especially pillows , blankets , and mattresses . They are also used as filling for winter clothing and outdoor bedding, such as quilted coats and sleeping bags . Goose and eider down have great loft ,
4371-502: Is called by some the Dyck texture. Melanin is often involved in the absorption of light; in combination with a yellow pigment, it produces a dull olive-green. In some birds, feather colors may be created, or altered, by secretions from the uropygial gland , also called the preen gland. The yellow bill colors of many hornbills are produced by such secretions. It has been suggested that there are other color differences that may be visible only in
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4512-408: Is caused by defective pigment production, though structural coloration will not be affected (as can be seen, for example, in blue-and-white budgerigars ). The blues and bright greens of many parrots are produced by constructive interference of light reflecting from different layers of structures in feathers. In the case of green plumage, in addition to yellow, the specific feather structure involved
4653-555: Is common in warm-blooded animals who need insulation to prevent excessive heat-loss. Pycnofibers were flexible, short filaments, about five to seven millimetres long and rather simple in structure with a hollow central canal. Pterosaur pelts might have been comparable in density to many Mesozoic mammals. Pterosaur filaments could share a common origin with feathers, as speculated in 2002 by Czerkas and Ji. In 2009, Kellner concluded that pycnofibers were structured similarly to theropod proto-feathers . Others were unconvinced, considering
4794-556: Is considered presumptuous. During the 18th, 19th, and early 20th centuries, there was a booming international trade in plumes for extravagant women's hats and other headgear (including in Victorian fashion ). Frank Chapman noted in 1886 that feathers of as many as 40 species of birds were used in about three-fourths of the 700 ladies' hats that he observed in New York City. For instance, South American hummingbird feathers were used in
4935-422: Is curved to behind, resulting in a rounded wing tip, which reduces induced drag . The wingfinger is also bent somewhat downwards. When standing, pterosaurs probably rested on their metacarpals, with the outer wing folded to behind. In this position, the "anterior" sides of the metacarpals were rotated to the rear. This would point the smaller fingers obliquely to behind. According to Bennett, this would imply that
5076-421: Is divided into three basic units. The first, called the propatagium ("fore membrane"), was the forward-most part of the wing and attached between the wrist and shoulder, creating the "leading edge" during flight. The brachiopatagium ("arm membrane") was the primary component of the wing, stretching from the highly elongated fourth finger of the hand to the hindlimbs. Finally, at least some pterosaur groups had
5217-427: Is likely that non-avian dinosaur species utilized plumage patterns for similar functions as modern birds before the origin of flight. In many cases, the physiological condition of the birds (especially males) is indicated by the quality of their feathers, and this is used (by the females) in mate choice . Additionally, when comparing different Ornithomimus edmontonicus specimens, older individuals were found to have
5358-418: Is short but powerfully built. It sports a large deltopectoral crest, to which the major flight muscles are attached. Despite the considerable forces exerted on it, the humerus is hollow or pneumatised inside, reinforced by bone struts. The long bones of the lower arm, the ulna and radius , are much longer than the humerus. They were probably incapable of pronation . A bone unique to pterosaurs, known as
5499-542: Is suppressed during embryological development of the alligator and so is not present in the scales of mature alligators. The presence of this homologous keratin in both birds and crocodilians indicates that it was inherited from a common ancestor. This may suggest that crocodilian scales, bird and dinosaur feathers, and pterosaur pycnofibres are all developmental expressions of the same primitive archosaur skin structures; suggesting that feathers and pycnofibers could be homologous. Molecular dating methods in 2011 show that
5640-475: The Indian peacock have been used in traditional medicine for snakebite, infertility, and coughs. Members of Scotland's Clan Campbell are known to wear feathers on their bonnets to signify authority within the clan. Clan chiefs wear three, chieftains wear two and an armiger wears one. Any member of the clan who does not meet the criteria is not authorized to wear feathers as part of traditional garb and doing so
5781-464: The Middle Triassic , though this has been disagreed upon. The lack of feathers present in large sauropods and ankylosaurs could be that feathers were suppressed by genomic regulators. Several studies of feather development in the embryos of modern birds, coupled with the distribution of feather types among various prehistoric bird precursors, have allowed scientists to attempt a reconstruction of
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5922-609: The United States and First Nations peoples in Canada as religious objects. In the United States, the religious use of eagle and hawk feathers is governed by the eagle feather law , a federal law limiting the possession of eagle feathers to certified and enrolled members of federally recognized Native American tribes. In South America, brews made from the feathers of condors are used in traditional medications. In India, feathers of
6063-494: The ornithischian dinosaurs Tianyulong and Psittacosaurus . The exact nature of these structures is still under study. However, it is believed that the stage-1 feathers (see Evolutionary stages section below) such as those seen in these two ornithischians likely functioned in display. In 2014, the ornithischian Kulindadromeus was reported as having structures resembling stage-3 feathers. The likelihood of scales evolving on early dinosaur ancestors are high. However, this
6204-477: The patagium , and the presence of both aktinofibrils and filaments on Jeholopterus ningchengensis and Sordes pilosus . The various forms of filament structure present on the anurognathids in the 2018 study would also require a form of decomposition that would cause the different 'filament' forms seen. They therefore conclude that the most parsimonious interpretation of the structures is that they are filamentous protofeathers. But Liliana D'Alba points out that
6345-401: The penguins , ratites and screamers. In most birds the feathers grow from specific tracts of skin called pterylae ; between the pterylae there are regions which are free of feathers called apterylae (or apteria ). Filoplumes and down may arise from the apterylae. The arrangement of these feather tracts, pterylosis or pterylography, varies across bird families and has been used in the past as
6486-427: The thorax . It was probably covered by thick muscle layers. The upper bone, the shoulder blade , was a straight bar. It was connected to a lower bone, the coracoid that is relatively long in pterosaurs. In advanced species, their combined whole, the scapulocoracoid, was almost vertically oriented. The shoulder blade in that case fitted into a recess in the side of the notarium, while the coracoid likewise connected to
6627-401: The α-keratins of mammalian hair , horns and hooves . The exact signals that induce the growth of feathers on the skin are not known, but it has been found that the transcription factor cDermo-1 induces the growth of feathers on skin and scales on the leg. There are two basic types of feather: vaned feathers which cover the exterior of the body, and down feathers which are underneath
6768-420: The "bat model" depicted pterosaurs as warm-blooded and furred, it would turn out to be more correct in certain aspects than Cuvier's "reptile model" in the long run. In 1834, Johann Jakob Kaup coined the term Pterosauria. Feather Feathers are epidermal growths that form a distinctive outer covering, or plumage , on both avian (bird) and some non-avian dinosaurs and other archosaurs . They are
6909-428: The 1990s, pterosaur finds and histological and ultraviolet examination of pterosaur specimens have provided incontrovertible proof: pterosaurs had pycnofiber coats. Sordes pilosus (which translates as "hairy demon") and Jeholopterus ninchengensis show pycnofibers on the head and body. The presence of pycnofibers strongly indicates that pterosaurs were endothermic (warm-blooded). They aided thermoregulation, as
7050-574: The Ctenochasmatidae: Ctenochasmatinae, Gnathosaurinae and Moganopterinae, while also including several basal genera. "Pterodactylus" micronyx Liaodactylus Ctenochasma Pterodaustro Beipiaopterus Gegepterus Kepodactylus Elanodactylus Feilongus Moganopterus Ardeadactylus Huanhepterus Plataleorhynchus Gnathosaurus [REDACTED] [REDACTED] [REDACTED] This pterosaur -related article
7191-618: The Middle Jurassic Stonesfield Slate formation in the United Kingdom , was considered the oldest known. This specimen supposedly represented a member of the family Ctenochasmatidae, though further examination suggested it actually belonged to a teleosaurid stem-crocodilian instead of a pterosaur. Below is cladogram following a topology recovered by Brian Andres, using the most recent iteration of his data set (Andres, 2021). Anders found that three subfamilies fall within
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#17328873280527332-451: The ability to expand from a compressed, stored state to trap large amounts of compartmentalized, insulating air. Feathers of large birds (most often geese ) have been and are used to make quill pens. Historically, the hunting of birds for decorative and ornamental feathers has endangered some species and helped to contribute to the extinction of others. Today, feathers used in fashion and in military headdresses and clothes are obtained as
7473-445: The air in the downstroke but yield in other directions. It has been observed that the orientation pattern of β-keratin fibers in the feathers of flying birds differs from that in flightless birds: the fibers are better aligned along the shaft axis direction towards the tip, and the lateral walls of rachis region show structure of crossed fibers. Feathers insulate birds from water and cold temperatures. They may also be plucked to line
7614-416: The ancestral state of dinosaurs. In 2010, a carcharodontosaurid named Concavenator corcovatus was found to have remiges on the ulna suggesting it might have had quill-like structures on the ams. However, Foth et al. 2014 disagress with the publication where they point out that the bumps on the ulna of Concavenator are on the anterolateral which is unlike remiges which are in a posterolateral on
7755-428: The ankle, sometimes reducing total length to a third. Typically, it was fused to the shinbone. The ankle was a simple, "mesotarsal", hinge. The, rather long and slender, metatarsus was always splayed to some degree. The foot was plantigrade, meaning that during the walking cycle the sole of the metatarsus was pressed onto the soil. There was a clear difference between early pterosaurs and advanced species regarding
7896-484: The ankles. The exact curvature of the trailing edge, however, is still equivocal. While historically thought of as simple leathery structures composed of skin, research has since shown that the wing membranes of pterosaurs were highly complex dynamic structures suited to an active style of flight. The outer wings (from the tip to the elbow) were strengthened by closely spaced fibers called actinofibrils . The actinofibrils themselves consisted of three distinct layers in
8037-427: The anterior surface of the distal syncarpal. The medial carpal bears a deep concave fovea that opens anteriorly, ventrally and somewhat medially, within which the pteroid articulates, according to Wilkinson. In derived pterodactyloids like pteranodontians and azhdarchoids , metacarpals I-III are small and do not connect to the carpus, instead hanging in contact with the fourth metacarpal. With these derived species,
8178-421: The barbs themselves are also branched and form the barbules . These barbules have minute hooks called barbicels for cross-attachment. Down feathers are fluffy because they lack barbicels, so the barbules float free of each other, allowing the down to trap air and provide excellent thermal insulation. At the base of the feather, the rachis expands to form the hollow tubular calamus (or quill ) which inserts into
8319-413: The breastbone. This way, both sides together made for a rigid closed loop, able to withstand considerable forces. A peculiarity was that the breastbone connections of the coracoids often were asymmetrical, with one coracoid attached in front of the other. In advanced species the shoulder joint had moved from the shoulder blade to the coracoid. The joint was saddle-shaped and allowed considerable movement to
8460-447: The broad ischium into an ischiopubic blade. Sometimes, the blades of both sides were also fused, closing the pelvis from below and forming the pelvic canal. The hip joint was not perforated and allowed considerable mobility to the leg. It was directed obliquely upwards, preventing a perfectly vertical position of the leg. The front of the pubic bones articulated with a unique structure, the paired prepubic bones. Together these formed
8601-474: The clade Anurognathidae ( Anurognathus , Jeholopterus , Vesperopterylus ) is debated. Anurognathids were highly specialized. Small flyers with shortened jaws and a wide gape, some had large eyes suggesting nocturnal or crepuscular habits, mouth bristles, and feet adapted for clinging. Parallel adaptations are seen in birds and bats that prey on insects in flight. Pterosaurs had a wide range of sizes, though they were generally large. The smallest species had
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#17328873280528742-445: The clades Ornithocheiroidea ( Istiodactylus , Ornithocheirus , Pteranodon ), Ctenochasmatoidea ( Ctenochasma , Pterodactylus ), Dsungaripteroidea ( Germanodactylus , Dsungaripterus ), and Azhdarchoidea ( Tapejara , Tupuxuara , Quetzalcoatlus ). The two groups overlapped in time, but the earliest pterosaurs in the fossil record are basal pterosaurs, and the latest pterosaurs are pterodactyloids. The position of
8883-399: The color and pattern of the feathers on Anchiornis and Tupandactylus could be determined. Anchiornis was found to have black-and-white-patterned feathers on the forelimbs and hindlimbs, with a reddish-brown crest. This pattern is similar to the coloration of many extant bird species, which use plumage coloration for display and communication, including sexual selection and camouflage. It
9024-421: The darker birds confirmed Gloger's rule . Although sexual selection plays a major role in the development of feathers, in particular, the color of the feathers it is not the only conclusion available. New studies are suggesting that the unique feathers of birds are also a large influence on many important aspects of avian behavior, such as the height at which different species build their nests. Since females are
9165-496: The descendants of the last common ancestor of the Saurischia and Ornithischia , which excludes the pterosaurs. Pterosaurs are nonetheless more closely related to birds and other dinosaurs than to crocodiles or any other living reptile, though they are not bird ancestors. Pterosaurs are also colloquially referred to as pterodactyls , particularly in fiction and journalism. However, technically, pterodactyl may refer to members of
9306-431: The description of the preserved integumentary structures on the two anurognathid specimens is still based upon gross morphology. She also points out that Pterorhynchus was described to have feathers to support the claim that feathers had a common origin with Ornithodirans but was argued against by several authors. The only method to assure if it was homologous to feathers is to use a scanning electron microscope. In 2022,
9447-544: The difference with the "quills" found on many of the bird-like maniraptoran specimens too fundamental. A 2018 study of the remains of two small Jurassic -age pterosaurs from Inner Mongolia , China , found that pterosaurs had a wide array of pycnofiber shapes and structures, as opposed to the homogeneous structures that had generally been assumed to cover them. Some of these had frayed ends, very similar in structure to four different feather types known from birds or other dinosaurs but almost never known from pterosaurs prior to
9588-410: 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. They were warm-blooded (endothermic), active animals. The respiratory system had efficient unidirectional "flow-through" breathing using air sacs , which hollowed out their bones to an extreme extent. Pterosaurs spanned
9729-476: The evolution of feathers—theropods with highly derived bird-like characteristics occurred at a later time than Archaeopteryx —suggesting that the descendants of birds arose before the ancestor. However, the discovery of Anchiornis huxleyi in the Late Jurassic Tiaojishan Formation (160 MYA) in western Liaoning in 2009 resolved this paradox. By predating Archaeopteryx , Anchiornis proves
9870-614: The evolution of proto-birds like Archaeopteryx and Microraptor zhaoianus . Another theory posits that the original adaptive advantage of early feathers was their pigmentation or iridescence, contributing to sexual preference in mate selection. Dinosaurs that had feathers or protofeathers include Pedopenna daohugouensis and Dilong paradoxus , a tyrannosauroid which is 60 to 70 million years older than Tyrannosaurus rex . The majority of dinosaurs known to have had feathers or protofeathers are theropods , however featherlike "filamentous integumentary structures" are also known from
10011-512: The existence of a modernly feathered theropod ancestor, providing insight into the dinosaur-bird transition. The specimen shows distribution of large pennaceous feathers on the forelimbs and tail, implying that pennaceous feathers spread to the rest of the body at an earlier stage in theropod evolution. The development of pennaceous feathers did not replace earlier filamentous feathers. Filamentous feathers are preserved alongside modern-looking flight feathers – including some with modifications found in
10152-538: The expense of health. A bird's feathers undergo wear and tear and are replaced periodically during the bird's life through molting . New feathers, known when developing as blood, or pin feathers , depending on the stage of growth, are formed through the same follicles from which the old ones were fledged. The presence of melanin in feathers increases their resistance to abrasion. One study notes that melanin based feathers were observed to degrade more quickly under bacterial action, even compared to unpigmented feathers from
10293-404: The extent of their wing membranes and it is possible that, like these groups, different species of pterosaur had different wing designs. Indeed, analysis of pterosaur limb proportions shows that there was considerable variation, possibly reflecting a variety of wing-plans. The bony elements of the arm formed a mechanism to support and extend the wing. Near the body, the humerus or upper arm bone
10434-419: The face that were used as tactile sensors. While feathers have been suggested as having evolved from reptilian scales , there are numerous objections to that idea, and more recent explanations have arisen from the paradigm of evolutionary developmental biology . Theories of the scale-based origins of feathers suggest that the planar scale structure was modified for development into feathers by splitting to form
10575-658: The feather-specific melanosome signaling found in extant birds are possibly homologous with those found in pterosaurs. Pterosaur fossils are very rare, due to their light bone construction. Complete skeletons can generally only be found in geological layers with exceptional preservation conditions, the so-called Lagerstätten . The pieces from one such Lagerstätte , the Late Jurassic Solnhofen Limestone in Bavaria , became much sought after by rich collectors. In 1784, Italian naturalist Cosimo Alessandro Collini
10716-411: The feathers of extant diving birds – in 80 million year old amber from Alberta. Two small wings trapped in amber dating to 100 mya show plumage existed in some bird predecessors. The wings most probably belonged to enantiornithes , a diverse group of avian dinosaurs. A large phylogenetic analysis of early dinosaurs by Matthew Baron, David B. Norman and Paul Barrett (2017) found that Theropoda
10857-432: The fifth toes as hooks. Another hypothesis held that they stretched the brachiopatagia, but in articulated fossils the fifth digits are always flexed towards the tail. Later it became popular to assume that these toes extended an uropatagium or cruropatagium between them. As the fifth toes were on the outside of the feet, such a configuration would only have been possible if these rotated their fronts outwards in flight. Such
10998-450: The forces caused by flapping the wings. The notarium included three to seven vertebrae, depending on the species involved but also on individual age. These vertebrae could be connected by tendons or a fusion of their neural spines into a "supraneural plate". Their ribs also would be tightly fused into the notarium. In general, the ribs are double headed. The sacrum consisted of three to ten sacral vertebrae. They too, could be connected via
11139-400: The forelimb digits besides the wingfinger have been lost altogether. The wingfinger accounts for about half or more of the total wing length. It normally consists of four phalanges. Their relative lengths tend to vary among species, which has often been used to distinguish related forms. The fourth phalanx is usually the shortest. It lacks a claw and has been lost completely by nyctosaurids. It
11280-417: The form of the fifth digit. Originally, the fifth metatarsal was robust and not very shortened. It was connected to the ankle in a higher position than the other metatarsals. It bore a long, and often curved, mobile clawless fifth toe consisting of two phalanges. The function of this element has been enigmatic. It used to be thought that the animals slept upside-down like bats, hanging from branches and using
11421-415: The fourth metacarpal has been enormously elongated, typically equalling or exceeding the length of the long bones of the lower arm. The fifth metacarpal had been lost. In all species, the first to third fingers are much smaller than the fourth, the "wingfinger", and contain two, three and four phalanges respectively. The smaller fingers are clawed, with the ungual size varying among species. In nyctosaurids
11562-467: The front of the snout, as an outgrowth of the premaxillae, or the rear of the skull as an extension of the parietal bones in which case it is called a "supraoccipital crest". Front and rear crests can be present simultaneously and might be fused into a single larger structure, the most expansive of which is shown by the Tapejaridae . Nyctosaurus sported a bizarre antler-like crest. The crests were only
11703-429: The genus Pterodactylus , and more broadly to members of the suborder Pterodactyloidea of the pterosaurs. Pterosaurs had a variety of lifestyles. Traditionally seen as fish-eaters, the group is now understood to have also included hunters of land animals, insectivores, fruit eaters and even predators of other pterosaurs. They reproduced by eggs , some fossils of which have been discovered. The anatomy of pterosaurs
11844-683: The ground, they 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 that at least some species were able to run, wade, and/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 may be homologous to
11985-460: The ground, they would have had an awkward sprawling posture, but the anatomy of their joints and strong claws would have made them effective climbers, and some may have even lived in trees. Basal pterosaurs were insectivores or predators of small vertebrates. Later pterosaurs ( pterodactyloids ) evolved many sizes, shapes, and lifestyles. Pterodactyloids had narrower wings with free hind limbs, highly reduced tails, and long necks with large heads. On
12126-464: The head and torso. The term "pycnofiber", meaning "dense filament", was coined by palaeontologist Alexander Kellner and colleagues in 2009. Pycnofibers were unique structures similar to, but not homologous (sharing a common origin) with, mammalian hair, an example of convergent evolution . A fuzzy integument was first reported from a specimen of Scaphognathus crassirostris in 1831 by Georg August Goldfuss , but had been widely doubted. Since
12267-412: The head making only a small angle with the shaft. This implies that the legs were not held vertically below the body but were somewhat sprawling. The shinbone was often fused with the upper ankle bones into a tibiotarsus that was longer than the thighbone. It could attain a vertical position when walking. The calf bone tended to be slender, especially at its lower end that in advanced forms did not reach
12408-427: The identification of species in forensic studies, particularly in bird strikes to aircraft. The ratios of hydrogen isotopes in feathers help in determining the geographic origins of birds. Feathers may also be useful in the non-destructive sampling of pollutants. The poultry industry produces a large amount of feathers as waste, which, like other forms of keratin, are slow to decompose. Feather waste has been used in
12549-401: The jaw joint was in a more forward position. The front lower jaw bones, the dentaries or ossa dentalia , were at the tip tightly fused into a central symphysis. This made the lower jaws function as a single connected whole, the mandible . The symphysis was often very thin transversely and long, accounting for a considerable part of the jaw length, up to 60%. If a crest was present on the snout,
12690-539: The legs. There has been considerable argument among paleontologists about whether the main wing membranes (brachiopatagia) attached to the hindlimbs, and if so, where. Fossils of the rhamphorhynchoid Sordes , the anurognathid Jeholopterus , and a pterodactyloid from the Santana Formation seem to demonstrate that the wing membrane did attach to the hindlimbs, at least in some species. However, modern bats and flying squirrels show considerable variation in
12831-402: The membrane from the ground. In Pterodactyloidea, the fifth metatarsal was much reduced and the fifth toe, if present, little more than a stub. This suggests that their membranes were split, increasing flight maneuverability. The first to fourth toes were long. They had two, three, four and five phalanges respectively. Often the third toe was longest; sometimes the fourth. Flat joints indicate
12972-421: The middle ones stiffened by elongated articulation processes, the zygapophyses , and chevrons . Such tails acted as rudders, sometimes ending at the rear in a vertical diamond-shaped or oval vane. In pterodactyloids, the tails were much reduced and never stiffened, with some species counting as few as ten vertebrae. The shoulder girdle was a strong structure that transferred the forces of flapping flight to
13113-477: The most complex integumentary structures found in vertebrates and an example of a complex evolutionary novelty. They are among the characteristics that distinguish the extant birds from other living groups. Although feathers cover most of the bird's body, they arise only from certain well-defined tracts on the skin. They aid in flight, thermal insulation, and waterproofing. In addition, coloration helps in communication and protection . The study of feathers
13254-575: The neck is typically longer than the torso. This length is not caused by an increase of the number of vertebrae, which is invariably seven. Some researchers include two transitional "cervicodorsals" which brings the number to nine. Instead, the vertebrae themselves became more elongated, up to eight times longer than wide. Nevertheless, the cervicals were wider than high, implying a better vertical than horizontal neck mobility. Pterodactyloids have lost all neck ribs. Pterosaur necks were probably rather thick and well-muscled, especially vertically. The torso
13395-483: The nest and provide insulation to the eggs and young. The individual feathers in the wings and tail play important roles in controlling flight. Some species have a crest of feathers on their heads. Although feathers are light, a bird's plumage weighs two or three times more than its skeleton, since many bones are hollow and contain air sacs. Color patterns serve as camouflage against predators for birds in their habitats, and serve as camouflage for predators looking for
13536-582: The nest. The height study found that birds that nest in the canopies of trees often have many more predator attacks due to the brighter color of feathers that the female displays. Another influence of evolution that could play a part in why feathers of birds are so colorful and display so many patterns could be due to that birds developed their bright colors from the vegetation and flowers that thrive around them. Birds develop their bright colors from living around certain colors. Most bird species often blend into their environment, due to some degree of camouflage, so if
13677-621: The nests of other species also have host-specific feather lice and these seem to be transmitted only after the young cuckoos leave the host nest. Birds maintain their feather condition by preening and bathing in water or dust . It has been suggested that a peculiar behavior of birds, anting , in which ants are introduced into the plumage, helps to reduce parasites, but no supporting evidence has been found. Bird feathers have long been used for fletching arrows . Colorful feathers such as those belonging to pheasants have been used to decorate fishing lures . Feathers are also valuable in aiding
13818-458: The original material. They may include horn crests, beaks or claw sheaths as well as the various flight membranes. Exceptionally, muscles were preserved. Skin patches show small round non-overlapping scales on the soles of the feet, the ankles and the ends of the metatarsals . They covered pads cushioning the impact of walking. Scales are unknown from other parts of the body. Most or all pterosaurs had hair -like filaments known as pycnofibers on
13959-462: The original primary function as the feathers simply would not have been capable of providing any form of lift. There have been suggestions that feathers may have had their original function in thermoregulation, waterproofing, or even as sinks for metabolic wastes such as sulphur. Recent discoveries are argued to support a thermoregulatory function, at least in smaller dinosaurs. Some researchers even argue that thermoregulation arose from bristles on
14100-463: The parasite species being specific to the host and coevolving with the host, making them of interest in phylogenetic studies. Feather holes are chewing traces of lice (most probably Brueelia spp. lice) on the wing and tail feathers. They were described on barn swallows , and because of easy countability, many evolutionary, ecological, and behavioral publications use them to quantify the intensity of infestation. Parasitic cuckoos which grow up in
14241-487: The past to dress some of the miniature birds featured in singing bird boxes . This trade caused severe losses to bird populations (for example, egrets and whooping cranes ). Conservationists led a major campaign against the use of feathers in hats. This contributed to passage of the Lacey Act in 1900, and to changes in fashion. The ornamental feather market then largely collapsed. More recently, rooster plumage has become
14382-432: The prime caregivers, evolution has helped select females to display duller colors down so that they may blend into the nesting environment. The position of the nest and whether it has a greater chance of being under predation has exerted constraints on female birds' plumage. A species of bird that nests on the ground, rather than the canopy of the trees, will need to have much duller colors in order not to attract attention to
14523-405: The pteroid bone, which may itself be a modified distal carpal. The proximal carpals are fused together into a "syncarpal" in mature specimens, while three of the distal carpals fuse to form a distal syncarpal. The remaining distal carpal, referred to here as the medial carpal, but which has also been termed the distal lateral, or pre-axial carpal, articulates on a vertically elongate biconvex facet on
14664-402: The pteroid in articulation with the proximal syncarpal, suggesting that the pteroid articulated with the 'saddle' of the radiale (proximal syncarpal) and that both the pteroid and preaxial carpal were migrated centralia. The pterosaur wrist consists of two inner (proximal, at the side of the long bones of the arm) and four outer (distal, at the side of the hand) carpals (wrist bones), excluding
14805-441: The pteroid pointed forward, extending the forward membrane and allowing it to function as an adjustable flap . This view was contradicted in a 2007 paper by Chris Bennett, who showed that the pteroid did not articulate as previously thought and could not have pointed forward, but rather was directed inward toward the body as traditionally interpreted. Specimens of Changchengopterus pani and Darwinopterus linglongtaensis show
14946-488: The pteroid, connected to the wrist and helped to support the forward membrane (the propatagium) between the wrist and shoulder. Evidence of webbing between the three free fingers of the pterosaur forelimb suggests that this forward membrane may have been more extensive than the simple pteroid-to-shoulder connection traditionally depicted in life restorations. The position of the pteroid bone itself has been controversial. Some scientists, notably Matthew Wilkinson, have argued that
15087-462: The rachis and herringbone pattern of the barbs. In the clade Deinonychosauria, the continued divergence of feathers is also apparent in the families Troodontidae and Dromaeosauridae . Branched feathers with rachis, barbs, and barbules were discovered in many members including Sinornithosaurus millenii , a dromaeosaurid found in the Yixian formation (124.6 MYA). Previously, a temporal paradox existed in
15228-631: The recent common ancestors of birds, Oviraptorosauria and Deinonychosauria . In 1998, the discovery of a feathered oviraptorosaurian, Caudipteryx zoui , challenged the notion of feathers as a structure exclusive to Avialae. Buried in the Yixian Formation in Liaoning, China, C. zoui lived during the Early Cretaceous Period. Present on the forelimbs and tails, their integumentary structure has been accepted as pennaceous vaned feathers based on
15369-412: The rictal bristles. Grebes are peculiar in their habit of ingesting their own feathers and feeding them to their young. Observations on their diet of fish and the frequency of feather eating suggest that ingesting feathers, particularly down from their flanks, aids in forming easily ejectable pellets. Contour feathers are not uniformly distributed on the skin of the bird except in some groups such as
15510-413: The same species, than those unpigmented or with carotenoid pigments. However, another study the same year compared the action of bacteria on pigmentations of two song sparrow species and observed that the darker pigmented feathers were more resistant; the authors cited other research also published in 2004 that stated increased melanin provided greater resistance. They observed that the greater resistance of
15651-433: The scale-feather converters Sox2 , Zic1 , Grem1 , Spry2 , and Sox18 . Feathers and scales are made up of two distinct forms of keratin , and it was long thought that each type of keratin was exclusive to each skin structure (feathers and scales). However, feather keratin is also present in the early stages of development of American alligator scales. This type of keratin, previously thought to be specific to feathers,
15792-586: The skull, the sutures between elements disappeared. In some later pterosaurs, the backbone over the shoulders fused into a structure known as a notarium , which served to stiffen the torso during flight, and provide a stable support for the shoulder blade . Likewise, the sacral vertebrae could form a single synsacrum while the pelvic bones fused also. Basal pterosaurs include the clades Dimorphodontidae ( Dimorphodon ), Campylognathididae ( Eudimorphodon , Campyognathoides ), and Rhamphorhynchidae ( Rhamphorhynchus , Scaphognathus ). Pterodactyloids include
15933-535: The species habitat is full of colors and patterns, the species would eventually evolve to blend in to avoid being eaten. Birds' feathers show a large range of colors, even exceeding the variety of many plants, leaf, and flower colors. The feather surface is the home for some ectoparasites, notably feather lice ( Phthiraptera ) and feather mites. Feather lice typically live on a single host and can move only from parents to chicks, between mating birds, and, occasionally, by phoresy . This life history has resulted in most of
16074-400: The study, suggesting homology. A response to this study was published in 2020, where it was suggested that the structures seen on the anurognathids were actually a result of the decomposition of aktinofibrils: a type of fibre used to strengthen and stiffen the wing. However, in a response to this, the authors of the 2018 paper point to the fact that the presence of the structures extend past
16215-467: The subfamily of feather β-keratins found in extant birds started to diverge 143 million years ago, suggesting the pennaceous feathers of Anchiornis were not made of the feather β-keratins present in extant birds. However, a study of fossil feathers from the dinosaur Sinosauropteryx and other fossils revealed traces of beta-sheet proteins, using infrared spectroscopy and sulfur-X-ray spectroscopy. The presence of abundant alpha-proteins in some fossil feathers
16356-405: The symphysis could feature a matching mandible crest, jutting out to below. Toothed species also bore teeth in their dentaries. The mandible opened and closed in a simple vertical or "orthal" up-and-down movement. The vertebral column of pterosaurs numbered between thirty-four and seventy vertebrae . The vertebrae in front of the tail were "procoelous": the cotyle (front of the vertebral body )
16497-405: The teeth mostly became conical. Front teeth were often longer, forming a "prey grab" in transversely expanded jaw tips, but size and position were very variable among species. With the derived Pterodactyloidea , the skulls became even more elongated, sometimes surpassing the combined neck and torso in length. This was caused by a stretching and fusion of the front snout bone, the premaxilla , with
16638-472: The term to the genus Pterodactylus or members of the Pterodactyloidea . In 1812 and 1817, Samuel Thomas von Soemmerring redescribed the original specimen and an additional one. He saw them as affiliated to birds and bats. Although he was mistaken in this, his "bat model" would be influential during the 19th century. In 1843, Edward Newman thought pterosaurs were flying marsupials . Ironically, as
16779-453: The time, distinct from previously known contemporary integumentary structures and more similar to those reported from mammalian hair and avian feathers. The feather fossils obtained from this specimen also suggest the presence of Stage IIIa feathers, a new discovery that indicates more complex feather structures were present in pterosaurs. The study describing this specimen further clarifies the timeline of avian feather evolution and suggests that
16920-422: The true extent of these crests has only been uncovered using ultraviolet photography. While fossil crests used to be restricted to the more advanced Pterodactyloidea, Pterorhynchus and Austriadactylus show that even some early pterosaurs possessed them. Like the upper jaws, the paired lower jaws of pterosaurs were very elongated. In advanced forms, they tended to be shorter than the upper cranium because
17061-412: The ulna of some birds, they consider it more likely that these are attachments for interosseous ligaments. This was refuted by Cuesta Fidalgo and her colleagues, they pointed out that these bumps on the ulna are posterolateral which is unlike that of interosseous ligaments. Since the 1990s, dozens of feathered dinosaurs have been discovered in the clade Maniraptora , which includes the clade Avialae and
17202-497: The ultraviolet region, but studies have failed to find evidence. The oil secretion from the uropygial gland may also have an inhibitory effect on feather bacteria. The reds, orange and yellow colors of many feathers are caused by various carotenoids. Carotenoid-based pigments might be honest signals of fitness because they are derived from special diets and hence might be difficult to obtain, and/or because carotenoids are required for immune function and hence sexual displays come at
17343-416: The upper jawbone, the maxilla . Unlike most archosaurs , the nasal and antorbital openings of pterodactyloid pterosaurs merged into a single large opening, called the nasoantorbital fenestra . This feature likely evolved to lighten the skull for flight. In contrast, the bones behind the eye socket contracted and rotated, strongly inclining the rear skull and bringing the jaw joint forward. The braincase
17484-438: The vaned feathers. The pennaceous feathers are vaned feathers. Also called contour feathers, pennaceous feathers arise from tracts and cover the entire body. A third rarer type of feather, the filoplume , is hairlike and are closely associated with pennaceous feathers and are often entirely hidden by them, with one or two filoplumes attached and sprouting from near the same point of the skin as each pennaceous feather, at least on
17625-422: The visible range. The wing feathers of male club-winged manakins Machaeropterus deliciosus have special structures that are used to produce sounds by stridulation . Some birds have a supply of powder down feathers that grow continuously, with small particles regularly breaking off from the ends of the barbules. These particles produce a powder that sifts through the feathers on the bird's body and acts as
17766-480: The webbing; however, that developmental process involves a tubular structure arising from a follicle and the tube splitting longitudinally to form the webbing. The number of feathers per unit area of skin is higher in smaller birds than in larger birds, and this trend points to their important role in thermal insulation, since smaller birds lose more heat due to the relatively larger surface area in proportion to their body weight. The miniaturization of birds also played
17907-416: The wing, forming a crisscross pattern when superimposed on one another. The function of the actinofibrils is unknown, as is the exact material from which they were made. Depending on their exact composition (keratin, muscle, elastic structures, etc.), they may have been stiffening or strengthening agents in the outer part of the wing. The wing membranes also contained a thin layer of muscle, fibrous tissue, and
18048-402: The wing. It faced sideways and somewhat upwards. The breastbone, formed by fused paired sterna , was wide. It had only a shallow keel. Via sternal ribs, it was at its sides attached to the dorsal ribs. At its rear, a row of belly ribs or gastralia was present, covering the entire belly. To the front, a long point, the cristospina , jutted obliquely upwards. The rear edge of the breastbone
18189-475: The wingfinger, able to describe the largest arc of any wing element, up to 175°, was not folded by flexion but by an extreme extension. The wing was automatically folded when the elbow was bowed. A laser-simulated fluorescence scan on Pterodactylus also identified a membranous "fairing" (area conjunctioning the wing with the body at the neck), as opposed to the feathered or fur-composed "fairing" seen in birds and bats respectively. The pelvis of pterosaurs
18330-671: The word pen itself is derived from the Latin penna , meaning feather. The French word plume can mean feather , quill , or pen . Feathers are among the most complex integumentary appendages found in vertebrates and are formed in tiny follicles in the epidermis , or outer skin layer, that produce keratin proteins . The β-keratins in feathers, beaks and claws – and the claws, scales and shells of reptiles – are composed of protein strands hydrogen-bonded into β-pleated sheets , which are then further twisted and crosslinked by disulfide bridges into structures even tougher than
18471-490: The yellow to red psittacofulvins (found in some parrots ) and the red turacin and green turacoverdin ( porphyrin pigments found only in turacos ). Structural coloration is involved in the production of blue colors, iridescence , most ultraviolet reflectance and in the enhancement of pigmentary colors. Structural iridescence has been reported in fossil feathers dating back 40 million years. White feathers lack pigment and scatter light diffusely; albinism in birds
18612-508: Was by assuming that primitive pterosaurs were scaly. A 2016 study analyzes the pulp morphology of the tail bristles of Psittacosaurus and finds they are similar to feathers but notes that they are also similar to the bristles on the head of the Congo peafowl , the beard of the turkey , and the spine on the head of the horned screamer . A reestimation of maximum likelihoods by paleontologist Thomas Holtz finds that filaments were more likely to be
18753-401: Was concave and into it fitted a convex extension at the rear of the preceding vertebra, the condyle . Advanced pterosaurs are unique in possessing special processes projecting adjacent to their condyle and cotyle, the exapophyses , and the cotyle also may possess a small prong on its midline called a hypapophysis. The necks of pterosaurs were relatively long and straight. In pterodactyloids,
18894-451: Was highly modified from their reptilian ancestors by the adaptation to flight. Pterosaur bones were hollow and air-filled, like those of birds . This provided a higher muscle attachment surface for a given skeletal weight. The bone walls were often paper-thin. They had a large and keeled breastbone for flight muscles and an enlarged brain able to coordinate complex flying behaviour. Pterosaur skeletons often show considerable fusion. In
19035-407: Was of moderate size compared to the body as a whole. Often the three pelvic bones were fused. The ilium was long and low, its front and rear blades projecting horizontally beyond the edges of the lower pelvic bones. Despite this length, the rod-like form of these processes indicates that the hindlimb muscles attached to them were limited in strength. The, in side view narrow, pubic bone fused with
19176-636: Was relatively large for reptiles. In some cases, fossilized keratinous beak tissue has been preserved, though in toothed forms, the beak is small and restricted to the jaw tips and does not involve the teeth. Some advanced beaked forms were toothless, such as the Pteranodontidae and Azhdarchidae , and had larger, more extensive, and more bird-like beaks. Some groups had specialised tooth forms. The Istiodactylidae had recurved teeth for eating meat. Ctenochasmatidae used combs of numerous needle-like teeth for filter feeding; Pterodaustro could have over
19317-403: Was relatively short and egg-shaped. The vertebrae in the back of pterosaurs originally might have numbered eighteen. With advanced species a growing number of these tended to be incorporated into the sacrum . Such species also often show a fusion of the front dorsal vertebrae into a rigid whole which is called the notarium after a comparable structure in birds. This was an adaptation to withstand
19458-674: Was shown to be an artefact of the fossilization process, as beta-protein structures are readily altered to alpha-helices during thermal degradation. In 2019, scientists found that genes for the production of feathers evolved at the base of archosauria, supporting that feathers were present at early ornithodirans and is consistent with the fossil record. Several non-avian dinosaurs had feathers on their limbs that would not have functioned for flight. One theory suggests that feathers originally evolved on dinosaurs due to their insulation properties; then, small dinosaur species which grew longer feathers may have found them helpful in gliding, leading to
19599-482: Was that if such creatures were still alive, only the sea was a credible habitat; Collini suggested it might be a swimming animal that used its long front limbs as paddles. A few scientists continued to support the aquatic interpretation even until 1830, when German zoologist Johann Georg Wagler suggested that Pterodactylus used its wings as flippers and was affiliated with Ichthyosauria and Plesiosauria . In 1800, Johann Hermann first suggested that it represented
19740-456: Was the deepest point of the thorax. Clavicles or interclavicles were completely absent. Pterosaur wings were formed by bones and membranes of skin and other tissues. The primary membranes attached to the extremely long fourth finger of each arm and extended along the sides of the body. Where they ended has been very controversial but since the 1990s a dozen specimens with preserved soft tissue have been found that seem to show they attached to
19881-400: Was the first scientist to describe a pterosaur fossil. At that time the concepts of evolution and extinction were imperfectly developed. The bizarre build of the pterosaur was shocking, as it could not clearly be assigned to any existing animal group. The discovery of pterosaurs would thus play an important role in the progress of modern paleontology and geology. Scientific opinion at the time
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