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109-465: Anhangueridae is a group of pterosaurs within the suborder Pterodactyloidea . They were among the last pterosaurs to possess teeth. A recent study discussing the group considered the Anhangueridae to be typified by a premaxillary crest and a lateral expansion in the distal rostrum. The same study presented a cladistic analysis, for which an "agreement subtree" was calculated. The Anhangueridae

218-402: 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

327-458: 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 ,

436-411: 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

545-743: A function is called cellular differentiation . Cells of meristematic tissue differentiate to form different types of permanent tissues. There are 2 types of permanent tissues: Simple permanent tissue is a group of cells which are similar in origin, structure, and function. They are of three types: Parenchyma (Greek, para – 'beside'; enchyma– infusion – 'tissue') is the bulk of a substance. In plants, it consists of relatively unspecialized living cells with thin cell walls that are usually loosely packed so that intercellular spaces are found between cells of this tissue. These are generally isodiametric, in shape. They contain small number of vacuoles or sometimes they even may not contain any vacuole. Even if they do so

654-604: A function of providing mechanical support. They do not have inter-cellular spaces between them. Lignin deposition is so thick that the cell walls become stronger, rigid and impermeable to water, which are also known as a stone cells or sclereids. These tissues are mainly of two types: sclerenchyma fiber and sclereids. Sclerenchyma fiber cells have a narrow lumen and are long, narrow and unicellular. Fibers are elongated cells that are strong and flexible, often used in ropes. Sclereids have extremely thick cell walls and are brittle, and are found in nutshells and legumes. The entire surface of

763-445: 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

872-400: 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

981-516: 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

1090-459: A much more inclusive group. The analysis found most of the ornithocheirids falling into this family, while Ornithocheirus itself was recovered as a basal member of Ornithocheirae . Hamipterus Iberodactylus Tropeognathus Coloborhynchus Siroccopteryx Uktenadactylus Caulkicephalus Guidraco Ludodactylus Anhanguera Liaoningopterus Cearadactylus Maaradactylus The clagogram below

1199-425: 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

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1308-411: 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

1417-535: A supporting tissue in stems of young plants. It provides mechanical support, elasticity, and tensile strength to the plant body. It helps in manufacturing sugar and storing it as starch. It is present in the margin of leaves and resists tearing effect of the wind. Sclerenchyma (Greek, Sclerous means hard and enchyma means infusion) consists of thick-walled, dead cells and protoplasm is negligible. These cells have hard and extremely thick secondary walls due to uniform distribution and high secretion of lignin and have

1526-449: 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,

1635-536: A thin and elastic primary cell wall made of cellulose . They are compactly arranged without inter-cellular spaces between them. Each cell contains a dense cytoplasm and a prominent cell nucleus . The dense protoplasm of meristematic cells contains very few vacuoles . Normally the meristematic cells are oval, polygonal , or rectangular in shape. Meristematic tissue cells have a large nucleus with small or no vacuoles because they have no need to store anything, as opposed to their function of multiplying and increasing

1744-464: 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

1853-416: 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

1962-408: 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

2071-453: 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

2180-594: A wide range of stretch lengths. It is found in such organs as sea anemone tentacles and the body wall of sea cucumbers . Skeletal muscle contracts rapidly but has a limited range of extension. It is found in the movement of appendages and jaws. Obliquely striated muscle is intermediate between the other two. The filaments are staggered and this is the type of muscle found in earthworms that can extend slowly or make rapid contractions. In higher animals striated muscles occur in bundles attached to bone to provide movement and are often arranged in antagonistic sets. Smooth muscle

2289-482: 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

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2398-622: 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

2507-466: Is a living tissue of primary body like Parenchyma . Cells are thin-walled but possess thickening of cellulose , water and pectin substances ( pectocellulose ) at the corners where a number of cells join. This tissue gives tensile strength to the plant and the cells are compactly arranged and have very little inter-cellular spaces. It occurs chiefly in hypodermis of stems and leaves. It is absent in monocots and in roots. Collenchymatous tissue acts as

2616-405: Is also known as conducting and vascular tissue. The common types of complex permanent tissue are: Xylem and phloem together form vascular bundles. Xylem (Greek, xylos = wood) serves as a chief conducting tissue of vascular plants. It is responsible for the conduction of water and inorganic solutes. Xylem consists of four kinds of cells: Xylem tissue is organised in a tube-like fashion along

2725-696: Is an equally important plant tissue as it also is part of the 'plumbing system' of a plant. Primarily, phloem carries dissolved food substances throughout the plant. This conduction system is composed of sieve-tube member and companion cells, that are without secondary walls. The parent cells of the vascular cambium produce both xylem and phloem. This usually also includes fibers, parenchyma and ray cells. Sieve tubes are formed from sieve-tube members laid end to end. The end walls, unlike vessel members in xylem, do not have openings. The end walls, however, are full of small pores where cytoplasm extends from cell to cell. These porous connections are called sieve plates. In spite of

2834-508: Is called an extracellular matrix . This matrix can be liquid or rigid. For example, blood contains plasma as its matrix and bone's matrix is rigid. Connective tissue gives shape to organs and holds them in place. Blood, bone, tendon, ligament, adipose, and areolar tissues are examples of connective tissues. One method of classifying connective tissues is to divide them into three types: fibrous connective tissue, skeletal connective tissue, and fluid connective tissue. Muscle cells (myocytes) form

2943-555: 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

3052-422: 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

3161-421: 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

3270-411: Is found in the walls of the uterus , bladder , intestines , stomach , oesophagus , respiratory airways , and blood vessels . Cardiac muscle is found only in the heart , allowing it to contract and pump blood through the body. Cells comprising the central nervous system and peripheral nervous system are classified as nervous (or neural) tissue. In the central nervous system, neural tissues form

3379-520: Is present. Cells of this type of tissue are roughly spherical or polyhedral to rectangular in shape, with thin cell walls . New cells produced by meristem are initially those of meristem itself, but as the new cells grow and mature, their characteristics slowly change and they become differentiated as components of meristematic tissue, being classified as: There are two types of meristematic Tissue 1.Primary meristem. 2.Secondary meristem. The cells of meristematic tissue are similar in structure and have

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3488-707: Is reproduced from Richards et al ., (2023), who based their data matrix on the data matrix in Holgado and Pêgas, (2020). In the paper they erect the clade Mythungini which comprises all Australian tropeognathines . Aerodraco Coloborhynchus Nicorhynchus Uktenadactylus Ludodactylus Caulkicephalus Guidraco Liaoningopterus Cearadactylus Maaradactylus AMNH 22555 Anhanguera Siroccopteryx Tropeognathus Amblydectes Ferrodraco Thapunngaka Mythunga [REDACTED] [REDACTED] [REDACTED] This pterosaur -related article

3597-418: 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

3706-477: Is somewhat variable. Most classification schemes combine a description of the cell-shape in the upper layer of the epithelium with a word denoting the number of layers: either simple (one layer of cells) or stratified (multiple layers of cells). However, other cellular features such as cilia may also be described in the classification system. Some common kinds of epithelium are listed below: Connective tissues are made up of cells separated by non-living material, which

3815-465: The histological stain , and the optical microscope . Developments in electron microscopy , immunofluorescence , and the use of frozen tissue-sections have enhanced the detail that can be observed in tissues. With these tools, the classical appearances of tissues can be examined in health and disease , enabling considerable refinement of medical diagnosis and prognosis . In plant anatomy , tissues are categorized broadly into three tissue systems:

3924-431: The brain and spinal cord . In the peripheral nervous system, neural tissues form the cranial nerves and spinal nerves , inclusive of the motor neurons . Mineralized tissues are biological tissues that incorporate minerals into soft matrices. Such tissues may be found in both plants and animals. Xavier Bichat introduced the word tissue into the study of anatomy by 1801. He was "the first to propose that tissue

4033-463: The ectoderm and endoderm (or their precursor in sponges ), with a small contribution from the mesoderm , forming the endothelium , a specialized type of epithelium that composes the vasculature . By contrast, a true epithelial tissue is present only in a single layer of cells held together via occluding junctions called tight junctions , to create a selectively permeable barrier. This tissue covers all organismal surfaces that come in contact with

4142-406: The epidermis , the ground tissue , and the vascular tissue . Plant tissues can also be divided differently into two types: Meristematic tissue consists of actively dividing cells and leads to increase in length and thickness of the plant. The primary growth of a plant occurs only in certain specific regions, such as in the tips of stems or roots. It is in these regions that meristematic tissue

4251-477: 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

4360-427: 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

4469-415: 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. Tissue (biology) Biological organisms follow this hierarchy : Cells < Tissue < Organ < Organ System < Organism The English word "tissue" derives from

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4578-428: 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

4687-480: The French word " tissu ", the past participle of the verb tisser, "to weave". The study of tissues is known as histology or, in connection with disease, as histopathology . Xavier Bichat is considered as the "Father of Histology". Plant histology is studied in both plant anatomy and physiology . The classical tools for studying tissues are the paraffin block in which tissue is embedded and then sectioned,

4796-420: The active contractile tissue of the body. Muscle tissue functions to produce force and cause motion, either locomotion or movement within internal organs. Muscle is formed of contractile filaments and is separated into three main types; smooth muscle , skeletal muscle and cardiac muscle . Smooth muscle has no striations when examined microscopically. It contracts slowly but maintains contractibility over

4905-428: 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

5014-484: 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

5123-427: 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,

5232-413: 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

5341-447: 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

5450-474: 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

5559-445: 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

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5668-456: The colourless substance that covers the sieve plate. Callose stays in solution as long as the cell contents are under pressure. Phloem transports food and materials in plants upwards and downwards as required. Animal tissues are grouped into four basic types: connective , muscle , nervous , and epithelial . Collections of tissues joined in units to serve a common function compose organs. While most animals can generally be considered to contain

5777-502: 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

5886-431: 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,

5995-544: 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

6104-410: 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

6213-433: The ends. They do not have end openings such as the vessels. The end overlap with each other, with pairs of pits present. The pit pairs allow water to pass from cell to cell. Though most conduction in xylem tissue is vertical, lateral conduction along the diameter of a stem is facilitated via rays. Rays are horizontal rows of long-living parenchyma cells that arise out of the vascular cambium. Phloem consists of: Phloem

6322-404: 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

6431-414: The external environment such as the skin , the airways, and the digestive tract. It serves functions of protection, secretion , and absorption, and is separated from other tissues below by a basal lamina . The connective tissue and the muscular are derived from the mesoderm. The nervous tissue is derived from the ectoderm. The epithelial tissues are formed by cells that cover the organ surfaces, such as

6540-399: The fact that their cytoplasm is actively involved in the conduction of food materials, sieve-tube members do not have nuclei at maturity. It is the companion cells that are nestled between sieve-tube members that function in some manner bringing about the conduction of food. Sieve-tube members that are alive contain a polymer called callose, a carbohydrate polymer, forming the callus pad/callus,

6649-676: 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

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6758-432: 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

6867-450: 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

6976-400: 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

7085-417: 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

7194-400: The four tissue types, the manifestation of these tissues can differ depending on the type of organism. For example, the origin of the cells comprising a particular tissue type may differ developmentally for different classifications of animals. Tissue appeared for the first time in the diploblasts , but modern forms only appeared in triploblasts . The epithelium in all animals is derived from

7303-415: 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

7412-473: 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

7521-429: 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

7630-400: The girth and length of the plant, with no intercellular spaces. Permanent tissues may be defined as a group of living or dead cells formed by meristematic tissue and have lost their ability to divide and have permanently placed at fixed positions in the plant body. Meristematic tissues that take up a specific role lose the ability to divide. This process of taking up a permanent shape, size and

7739-683: 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

7848-460: 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

7957-464: 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

8066-412: 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

8175-401: 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,

8284-547: 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

8393-471: The main axes of stems and roots. It consists of a combination of parenchyma cells, fibers, vessels, tracheids, and ray cells. Longer tubes made up of individual cellssels tracheids, while vessel members are open at each end. Internally, there may be bars of wall material extending across the open space. These cells are joined end to end to form long tubes. Vessel members and tracheids are dead at maturity. Tracheids have thick secondary cell walls and are tapered at

8502-402: 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

8611-421: 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

8720-575: 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

8829-458: 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

8938-411: The plant consists of a single layer of cells called epidermis or surface tissue. The entire surface of the plant has this outer layer of the epidermis. Hence it is also called surface tissue. Most of the epidermal cells are relatively flat. The outer and lateral walls of the cell are often thicker than the inner walls. The cells form a continuous sheet without intercellular spaces. It protects all parts of

9047-464: The plant. The outer epidermis is coated with a waxy thick layer called cutin which prevents loss of water. The epidermis also consists of stomata (singular:stoma) which helps in transpiration . The complex permanent tissue consists of more than one type of cells having a common origin which work together as a unit. Complex tissues are mainly concerned with the transportation of mineral nutrients, organic solutes (food materials), and water. That's why it

9156-405: 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

9265-402: 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

9374-441: 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

9483-488: 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

9592-586: 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

9701-400: 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

9810-639: The surface of skin , the airways , surfaces of soft organs, the reproductive tract , and the inner lining of the digestive tract . The cells comprising an epithelial layer are linked via semi-permeable, tight junctions ; hence, this tissue provides a barrier between the external environment and the organ it covers. In addition to this protective function, epithelial tissue may also be specialized to function in secretion , excretion and absorption . Epithelial tissue helps to protect organs from microorganisms, injury, and fluid loss. Functions of epithelial tissue: There are many kinds of epithelium, and nomenclature

9919-405: 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 )

10028-405: 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

10137-480: 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

10246-453: 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

10355-422: 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

10464-416: 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

10573-654: The vacuole is of much smaller size than of normal animal cells. This tissue provides support to plants and also stores food. Chlorenchyma is a special type of parenchyma that contains chlorophyll and performs photosynthesis. In aquatic plants, aerenchyma tissues, or large air cavities, give support to float on water by making them buoyant. Parenchyma cells called idioblasts have metabolic waste. Spindle shaped fibers are also present in this cell to support them and known as prosenchyma, succulent parenchyma also noted. In xerophytes , parenchyma tissues store water. Collenchyma (Greek, 'Colla' means gum and 'enchyma' means infusion)

10682-416: 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

10791-402: 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

10900-475: 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

11009-401: 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,

11118-503: Was found to be sister taxon to the large crested Tropeognathus . There are competing theories of ornithocheiromorph phylogeny (evolutionary relationships). Below is cladogram following a topology recovered by Brian Andres, using the most recent iteration of his data set. Aerodraco sedgwickii Liaoningopterus gui Anhanguera robustus Anhanguera piscator Anhanguera blittersdorffi The cladogram below follows Pêgas et al. (2019), who recovered Anhangueridae as

11227-451: 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

11336-407: 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

11445-643: 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

11554-403: 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

11663-482: 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

11772-456: 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

11881-400: 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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