Pterosaurs (/ˈtɛrəˌsɔːr, ˈtɛroʊ-/; from Greek, meaning "winged lizard") were flying reptiles of the extinct clade or 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 a membrane of skin, muscle, and other tissues stretching from the ankles to a dramatically lengthened fourth finger.
Early species had long, fully toothed jaws and long tails, while later forms had a highly reduced tail, and some lacked teeth. Many sported furry coats made up of hair-like filaments known as pycnofibers, which covered their bodies and parts of their wings. Pterosaurs spanned a wide range of adult sizes, from the very small anurognathids to the largest known flying creatures of all time, including Quetzalcoatlus and Hatzegopteryx.
Pterosaurs are often referred to in the popular media and by the general public as "flying dinosaurs", but the term "dinosaur" is restricted to just those reptiles descended from the last common ancestor of the groups Saurischia and Ornithischia (clade Dinosauria, which includes birds), and current scientific consensus is that this group excludes the pterosaurs, as well as the various groups of extinct marine reptiles, such as ichthyosaurs, plesiosaurs, and mosasaurs.
Unlike these other reptiles, pterosaurs are nonetheless more closely related to birds and dinosaurs than to crocodiles or any other living reptile.[b] Pterosaurs are also colloquially referred to as pterodactyls, particularly in fiction and by journalists. However, technically, pterodactyl only refers to members of the genus Pterodactylus, and more broadly to members of the suborder Pterodactyloidea of the pterosaurs.
|Replica Geosternbergia sternbergi skeletons, female (left) and male (right)|
|Distribution of pterosaur fossil locations. Colored species or genera names correspond to their taxonomic group.[a]|
The anatomy of pterosaurs was highly modified from their reptilian ancestors by the adaption to flight. Pterosaur bones were hollow and air-filled, like the bones of birds. They had a keeled breastbone that was developed for the attachment of flight muscles and an enlarged brain that shows specialised features associated with flight. 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.
Pterosaur wings were formed by 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 to the ankles.
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 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 a unique, complex circulatory system of looping blood vessels.
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 (see Paleobiology section below) into the wing membrane.
The pterosaur wing membrane is divided into three basic units. The first, called the propatagium ("first membrane"), was the forward-most part of the wing and attached between the wrist and shoulder, creating the "leading edge" during flight. This membrane may have incorporated the first three fingers of the hand, as evidenced in some specimens. The brachiopatagium ("arm membrane") was the primary component of the wing, stretching from the highly elongated fourth finger of the hand to the hind limbs (though where exactly on the hind limbs it anchored is controversial and may have varied between species, see below). Finally, at least some pterosaur groups had 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). It is generally agreed though that non-pterodactyloid pterosaurs had a broader uro/cruropatagium, with pterodactyloids only having membranes running along the legs.
A bone unique to pterosaurs, known as the pteroid, connected to the wrist and helped to support a 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 the pteroid pointed forward, extending the forward membrane. 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 inward toward the body as traditionally thought. Peters (2009) proposed that the pteroid articulated with the ‘saddle' of the radiale (proximal syncarpal) and both the pteroid and preaxial carpal were migrated centralia. This view of the articulation of the pteroid has since been supported by specimens of Changchengopterus pani and Darwinopterus linglongtaensis, both of which show the pteroid in articulation with the proximal syncarpal.
The pterosaur wrist consists of two inner (proximal) and four outer (distal) carpals (wrist bones), excluding 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 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. 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; in nyctosaurids the forelimb digits besides the wingfinger have been lost altogether.
There has been considerable argument among paleontologists about whether the main wing membranes (brachiopatagia) attached to the hind limbs, 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 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. Many, if not all, pterosaurs also had webbed feet.
Most pterosaur skulls had elongated jaws with a full complement of needle-like teeth. 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 pteranodonts and azhdarchids, and had larger, more extensive, and more bird-like beaks.
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.
Some species of pterosaurs featured elaborate crests. The first and perhaps best known of these is the distinctive backward-pointing crest of some Pteranodon species, though a few pterosaurs, such as the tapejarids and Nyctosaurus, sported extremely large crests that often incorporated keratinous or other soft tissue extensions of the bony crest base.
Since the 1990s, new discoveries and more thorough study of old specimens have shown that crests are far more widespread among pterosaurs than previously thought, due mainly to the fact that they were frequently extended by or composed completely of keratin, which does not fossilize as often as bone. In the case of pterosaurs like Pterorhynchus and Pterodactylus, the true extent of these crests has only been uncovered using ultraviolet photography. The discovery of Pterorynchus and Austriadactylus, both crested "rhamphorhynchoids", showed that even primitive pterosaurs had crests (previously, crests were thought to be restricted to the more advanced pterodactyloids).
At least some pterosaurs had hair-like filaments known as pycnofibers on the head and body, similar to, but not homologous (sharing a common origin) with, mammalian hair. A fuzzy integument was first reported from a specimen of Scaphognathus crassirostris in 1831 by Goldfuss, and recent pterosaur finds and the technology for histological and ultraviolet examination of pterosaur specimens have provided incontrovertible proof: pterosaurs had pycnofiber coats. Pycnofibers were not true hair as seen in mammals, but a unique structure that developed a similar appearance. Although, in some cases, actinofibrils (internal structural fibers) in the wing membrane have been mistaken for pycnofibers or true hair, some fossils, such as those of Sordes pilosus (which translates as "hairy demon") and Jeholopterus ninchengensis, do show the unmistakable imprints of pycnofibers on the head and body, not unlike modern-day bats, another example of convergent evolution. The head-coats do not cover the pterosaur's large jaws in many of the specimens found so far.
The presence of pycnofibers (and the demands of flight) imply that pterosaurs were endothermic (warm-blooded). The absence of pycnofibers on pterosaur wings suggests that the coat did not have an aerodynamic function, lending support to the idea that pycnofibers evolved to aid pterosaur thermoregulation, as is common in warm-blooded animals, insulation being necessary to conserve the heat created by an endothermic metabolism.[c]
Pterosaur "hair" was so obviously distinct from mammalian fur and other animal integuments, it required a new, separate name. The term "pycnofiber", meaning "dense filament", was first coined in a paper on the soft tissue impressions of Jeholopterus by palaeontologist Alexander W.A. Kellner and colleagues in 2009. Research into the genetic code of American alligator embryos could suggest that pycnofibres, crocodile scutes and avian feathers are developmentally homologous, based on the construction of their beta-keratin.
Some researchers (Czerkas and Ji, 2002) have speculated that pycnofibers were an antecedent of proto-feathers, but the available impressions of pterosaur integuments are not like the "quills" found on many of the bird-like maniraptoran specimens in the fossil record. Pterosaur pycnofibers were structured similarly to theropod proto-feathers. Pycnofibers were flexible, short filaments, "only 5–7mm in some specimens" and rather simple, "apparently lacking any internal detail aside from a central canal". Pterosaur "pelts" found "preserved in concentrated, dense mats of fibers, similar to those found surrounding fossilized mammals" suggest coats with a thickness comparable to many Mesozoic mammals,[d] at least on the parts of the pterosaur covered in pycnofibers. The coat thickness, and surface area covered, definitely varied by pterosaur species.
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 homogenous structure generally considered to cover them. The analysis found that at least some of these were very similar in structure to 4 different feather structures commonly known from birds and dinosaurs but almost never known from pterosaurs prior to the study. It is unknown if these "feathers" share a common ancestry with bird feathers or independently evolved from them, but the study's senior author, Mike Benton, has stated that despite heavy analysis, there was virtually no recorded difference between the structures and bird or dinosaur feathers, and they thus likely share a common ancestry with them.
The first pterosaur fossil was described by the Italian naturalist Cosimo Alessandro Collini in 1784. Collini misinterpreted his specimen as a seagoing creature that used its long front limbs as paddles. A few scientists continued to support the aquatic interpretation even until 1830, when the German zoologist Johann Georg Wagler suggested that Pterodactylus used its wings as flippers. Georges Cuvier first suggested that pterosaurs were flying creatures in 1801, and coined the name "Ptero-dactyle" in 1809 for the specimen recovered in Germany. However, due to the standardization of scientific names, the official name for this genus became Pterodactylus, though the name "pterodactyl" continued to be popularly and incorrectly applied to all members of Pterosauria. Paleontologists now avoid using "pterodactyl" and prefer the term "pterosaur". They relegate the term "pterodactyl" specifically for members of the genus Pterodactylus or more broadly for members of the suborder Pterodactyloidea.
Katsufumi Sato, a Japanese scientist, did calculations using modern birds and concluded that it was impossible for a pterosaur to stay aloft. In the book Posture, Locomotion, and Paleoecology of Pterosaurs it is theorized that they were able to fly due to the oxygen-rich, dense atmosphere of the Late Cretaceous period. However, both Sato and the authors of Posture, Locomotion, and Paleoecology of Pterosaurs based their research on the now outdated theories of pterosaurs being seabird-like, and the size limit does not apply to terrestrial pterosaurs, such as azhdarchids and tapejarids. Furthermore, Darren Naish concluded that atmospheric differences between the present and the Mesozoic were not needed for the giant size of pterosaurs.
Another issue that has been difficult to understand is how they took off. Earlier suggestions were that pterosaurs were largely cold-blooded gliding animals, deriving warmth from the environment like modern lizards, rather than burning calories. In this case, it was unclear how the larger ones of enormous size, with an inefficient cold-blooded metabolism, could manage a bird-like takeoff strategy, using only the hind limbs to generate thrust for getting airborne. Later research shows them instead as being warm-blooded and having powerful flight muscles, and using the flight muscles for walking as quadrupeds. Mark Witton of the University of Portsmouth and Mike Habib of Johns Hopkins University suggested that pterosaurs used a vaulting mechanism to obtain flight. The tremendous power of their winged forelimbs would enable them to take off with ease. Once aloft, pterosaurs could reach speeds of up to 120 kilometres per hour (75 mph) and travel thousands of kilometres.
In 1985, the Smithsonian Institution commissioned aeronautical engineer Paul MacCready to build a half-scale working model of Quetzalcoatlus northropi. The replica was launched with a ground-based winch. It flew several times in 1986 and was filmed as part of the Smithsonian's IMAX film On the Wing. However, the model was not anatomically correct and embodied vertical and horizontal tail stabilizers that pterosaurs did not have.
A 2009 study showed that pterosaurs had a lung-and-air-sac system and a precisely controlled skeletal breathing pump, which supports a flow-through pulmonary ventilation model in pterosaurs, analogous to that of birds. The presence of a subcutaneous air sac system in at least some pterodactyloids would have further reduced the density of the living animal. Like modern crocodilians, pterosaurs appeared to have had a hepatic piston, seeing as their shoulder-pectoral girdles were too inflexible to move the sternum as in birds, and they possessed strong gastralia. Thus, their respiratory system had characteristics comparable to both modern archosaur clades.
An X-ray study of pterosaur brain cavities revealed that the animals (Rhamphorhynchus muensteri and Anhanguera santanae) had massive flocculi. The flocculus is a brain region that integrates signals from joints, muscles, skin and balance organs. The pterosaurs' flocculi occupied 7.5% of the animals' total brain mass, more than in any other vertebrate. Birds have unusually large flocculi compared with other animals, but these only occupy between 1 and 2% of total brain mass.
The flocculus sends out neural signals that produce small, automatic movements in the eye muscles. These keep the image on an animal's retina steady. Pterosaurs may have had such a large flocculus because of their large wing size, which would mean that there was a great deal more sensory information to process. The low relative mass of the flocculi in birds is also a result of birds having a much larger brain overall; though this has been considered an indication that pterosaurs lived in a structurally simpler environment or had less complex behaviour compared to birds, recent studies of crocodilians and other reptiles show that it is common for sauropsids to achieve high intelligence levels with small brains. Studies on the endocast of Allkaruen show that brain evolution in pterodactyloids was a modular process.
Pterosaurs' hip sockets are oriented facing slightly upwards, and the head of the femur (thigh bone) is only moderately inward facing, suggesting that pterosaurs had an erect stance. It would have been possible to lift the thigh into a horizontal position during flight, as gliding lizards do.
There was considerable debate whether pterosaurs ambulated as quadrupeds or as bipeds. In the 1980s, paleontologist Kevin Padian suggested that smaller pterosaurs with longer hindlimbs, such as Dimorphodon, might have walked or even ran bipedally, in addition to flying, like road runners. However, a large number of pterosaur trackways were later found with a distinctive four-toed hind foot and three-toed front foot; these are the unmistakable prints of pterosaurs walking on all fours.
Fossil footprints show that pterosaurs stood with the entire foot in contact with the ground (plantigrade), in a manner similar to many mammals like humans and bears. Footprints from azhdarchids and several unidentified species show that pterosaurs walked with an erect posture with their four limbs held almost vertically beneath the body, an energy-efficient stance used by most modern birds and mammals, rather than the sprawled limbs of modern reptiles. Indeed, erect-limbs may be omnipresent in pterosaurs.
Though traditionally depicted as ungainly and awkward when on the ground, the anatomy of some pterosaurs (particularly pterodactyloids) suggests that they were competent walkers and runners. Early pterosaurs have long been considered particularly cumbersome locomotors due to the presence of large cruropatagia, but they too appear to have been generally efficient on the ground.
The forelimb bones of azhdarchids and ornithocheirids were unusually long compared to other pterosaurs, and, in azhdarchids, the bones of the arm and hand (metacarpals) were particularly elongated. Furthermore, as a whole, azhdarchid front limbs were proportioned similarly to fast-running ungulate mammals. Their hind limbs, on the other hand, were not built for speed, but they were long compared with most pterosaurs, and allowed for a long stride length. While azhdarchid pterosaurs probably could not run, they would have been relatively fast and energy efficient.
The relative size of the hands and feet in pterosaurs (by comparison with modern animals such as birds) may indicate the type of lifestyle pterosaurs led on the ground. Azhdarchid pterosaurs had relatively small feet compared to their body size and leg length, with foot length only about 25%–30% the length of the lower leg. This suggests that azhdarchids were better adapted to walking on dry, relatively solid ground. Pteranodon had slightly larger feet (47% the length of the tibia), while filter-feeding pterosaurs like the ctenochasmatoids had very large feet (69% of tibial length in Pterodactylus, 84% in Pterodaustro), adapted to walking in soft muddy soil, similar to modern wading birds. Though clearly forelimb-based launchers, basal pterosaurs have hindlimbs well adapted for hopping, suggesting a connection with archosaurs such as Scleromochlus.
Tracks made by ctenochasmatoids indicate that these pterosaurs swam using their hindlimbs. In general, these have large hindfeet and long torsos, indicating that they were probably more adapted for swimming than other pterosaurs. Pteranodontians conversely have several speciations in their humeri interpreted to have been suggestive of a water-based version of the typical quadrupedal launch, and several like boreopterids must have foraged while swimming, as they seem incapable of frigatebird-like aerial hawking. These adaptations are also seen in terrestrial pterosaurs like azhdarchids, which presumably still needed to launch from water in case they found themselves in it. The nyctosaurid Alcione may display adaptations for wing-propelled diving like modern gannets and tropicbirds.
Traditionally, almost all pterosaurs were seen as surface-feeding piscivores, a view that still dominates popular culture. In reality, however, the majority of pterosaurs are now thought to have been terrestrial carnivores, omnivores or insectivores.
One of the few groups that were never thought to be piscivores are the anurognathids; these were instead thought to be nocturnal, aerial insectivores, a view still maintained today. With highly flexible joints on the wing finger, a broad, triangular wing shape, large eyes and short tail, these pterosaurs were likely analogous to nightjars or some of today's insectivorous bats, being capable of high manoeuvrability at relatively low speeds.
Dimorphodon has been envisioned as a puffin analogue in the past, but its jaw structure and gait, combined with its poor flight capabilities, indicate that it was a terrestrial/semiarboreal feeder. It seems to have been a predator of small mammals, squamates, and large insects.
Campylognathoides is often seen either as a generalist or a terrestrial predator of small vertebrates, based on its robust dentition. The highly robust, "gorilla-like" humerus and a high-aspect wing morphology, similar to that of falcons, suggest it may have been capable of grabbing prey on the wing.
Eudimorphodonts can be divided into two major categories: those with long, robust wings similar to Campylognathoides, and those with long, slender wings. Species in the former category, including Carniadactylus and Eudimorphodon itself, were highly aerial animals and fast, agile flyers. The former was almost certainly insectivorous due to its small size; Eudimorphodon has been found with fish remains in its stomach, but its dentition suggests an opportunistic diet. Slender-winged species, such as Austriadactylus and Caviramus, were likely terrestrial/semiarboreal in habits, and potentially generalists. Caviramus likely had a strong bite force, indicating an adaptation towards hard foods. All eudimorphodonts possessed well-developed molariform teeth and could chew their food, as indicated by the tooth wear on Caviramus and Eudimorphodon teeth. Austriadactylus and Eudimorphodon had a pair of these molariform teeth developed into enlarged fangs.
Rhamphorhynchids can be roughly classified into two categories. One is the longirostrine bauplan, with long, slender wings, needle-like dentition and long, thin jaws, represented by species akin to Rhamphorhynchus itself or Dorygnathus. These taxa were piscivores. The other group is the "robust-jawed" bauplan, represented by species such as Sericipterus, Scaphognathus and Harpactognathus, which have more robust jaws and teeth (which were ziphont in Sericipterus), and shorter, broader wings. These were either terrestrial/aerial predators of vertebrates or corvid-like generalists.
Wukongopterids like Darwinopterus were first seen as aerial predators; however, as they lack the robust jaw structure or powerful flying muscles of Campylognathoides or the "robust-jawed" rhamphorhynchids, they are now seen as arboreal or semiterrestrial insectivores. Darwinopterus robustidens, in particular, seems to have been a beetle specialist.
Among pterodactyloids, a greater variation in diet is present. Pteranodontia contained many piscivorous taxa, such as ornithocheirans, boreopterids, pteranodontids and nyctosaurids. Some amount of niche partitioning seems to have been present: ornithocheirans and the later nyctosaurs were likely aerial dip-feeders like today's frigatebirds (with the exception of the plunge-diving adapted Alcione), while boreopterids were likely freshwater diving animals similar to cormorants or Platanista river dolphins, and pteranodonts were likely pelagic plunge-divers akin to boobies and gannets. The biggest exception among this group are the istiodactylids, which were likely primarily scavengers. It has been found that some ornithocheirids hunted terrestrial prey.
Archaeopterodactyloidea contained many pterosaurs that obtained food in coastal or freshwater habitats. Germanodactylus and Pterodactylus were likely piscivores, while the Ctenochasmatidae were suspension feeders, their numerous fine teeth to filter small organisms from shallow water. Pterodaustro in particular has been noted for its adaptations for flamingo-like filter-feeding. The diet of Cycnorhamphus, on the other hand, is an enigma - its unusually curved jaws show little indication of one diet over another. Hypothesized prey items include shellfish and jellyfish.
In contrast, Azhdarchoidea mostly contained terrestrial pterosaurs. Tapejarids are considered arboreal omnivores, feeding heavily on vegetation, but possibly also on small insects and vertebrates. Dsungaripterids are traditionally thought of as being specialist molluscivores, using their powerful jaws to crush the shells of molluscs and crustaceans. While this remains the dominant view of dsungaripterid paleobiology today, some have suggested that they were generalistic omnivores eating a variety of hard foods, as dsungaripterids are better adapted to terrestrial movement rather than wading and are found in inland deposits. Thalassodromids were likely terrestrial carnivores. Thalassodromeus itself was named after a fishing method known as "skim-feeding", which it (and every other known pterosaur) was physically incapable of. Instead, it seems to have been an unusually predatory pterosaur, pursuing relatively large prey, similar in ecology to phorusrhacids. Support for this lifestyle comes in the form of reinforced jaw joints and a relatively high bite force.
Azhdarchids are now well known as being terrestrial predators akin to ground hornbills or some storks, eating any prey item they could swallow whole. Two major exceptions to this are Hatzegopteryx, which was a robustly built raptorial predator of relatively large prey, including medium-sized dinosaurs; and Alanqa, which may have been a specialist molluscivore.
Lonchodectids are known to have had bodily proportions similar to those of azhdarchoids, and were probably similarly terrestrial. They are noted for rather unusual dentitions, however, and the possible member Prejanopterus possesses a bizarrely curved upper jaw that might indicate some specialized lifestyle.
Pterosaurs are known to have been eaten by theropods. In the 1 July 2004 edition of Nature, paleontologist Eric Buffetaut discusses an early Cretaceous fossil of three cervical vertebrae of a pterosaur with the broken tooth of a spinosaur, most likely Irritator, embedded in it. The vertebrae are known not to have been eaten and exposed to digestion, as the joints are still articulated.
While very little is known about pterosaur reproduction, it is believed that, similar to all dinosaurs, all pterosaurs reproduced by laying eggs, though such findings are very rare. The first known pterosaur egg was found in the quarries of Liaoning, the same place that yielded feathered dinosaurs. The egg was squashed flat with no signs of cracking, so evidently the eggs had leathery shells, as in modern lizards. This was supported by the description of an additional pterosaur egg belonging to the genus Darwinopterus, described in 2011, which also had a leathery shell and, also like modern reptiles but unlike birds, was fairly small compared to the size of the mother. In 2014 five unflattened eggs from the species Hamipterus tianshanensis were found in an Early Cretaceous deposit in northwest China. Examination of the shells by scanning electron microscopy showed the presence of a thin calcareous eggshell layer with a membrane underneath. A study of pterosaur eggshell structure and chemistry published in 2007 indicated that it is likely pterosaurs buried their eggs, like modern crocodiles and turtles. Egg-burying would have been beneficial to the early evolution of pterosaurs, as it allows for more weight-reducing adaptations, but this method of reproduction would also have put limits on the variety of environments pterosaurs could live in, and may have disadvantaged them when they began to face ecological competition from birds.
A Darwinopterus specimen showcases that at least some pterosaurs had a pair of functional ovaries, as opposed to the single functional ovary in birds, dismissing the reduction of functional ovaries as a requirement for powered flight.
Wing membranes preserved in pterosaur embryos are well developed, suggesting that pterosaurs were ready to fly soon after birth. Fossils of pterosaurs only a few days to a week old (called "flaplings") have been found, representing several pterosaur families, including pterodactylids, rhamphorhinchids, ctenochasmatids and azhdarchids. All preserve bones that show a relatively high degree of hardening (ossification) for their age, and wing proportions similar to adults. In fact, many pterosaur flaplings have been considered adults and placed in separate species in the past. Additionally, flaplings are normally found in the same sediments as adults and juveniles of the same species, such as the Pterodactylus and Rhamphorhynchus flaplings found in the Solnhofen limestone of Germany, and Pterodaustro flaplings from Brazil. All are found in deep aquatic environment far from shore.
It is not known whether pterosaurs practiced any form of parental care, but their ability to fly as soon as they emerged from the egg and the numerous flaplings found in environments far from nests and alongside adults has led most researchers, including Christopher Bennett and David Unwin, to conclude that the young were dependent on their parents for a relatively short period of time, during a period of rapid growth while the wings grew long enough to fly, and then left the nest to fend for themselves, possibly within days of hatching. Alternatively, they may have used stored yolk products for nourishment during their first few days of life, as in modern reptiles, rather than depend on parents for food.
Growth rates of pterosaurs once they hatched varied across different groups. In more primitive, long-tailed pterosaurs ("rhamphorhynchoids"), such as Rhamphorhynchus, the average growth rate during the first year of life was 130% to 173%, slightly faster than the growth rate of alligators. Growth in these species slowed after sexual maturity, and it would have taken more than three years for Rhamphorhynchus to attain maximum size. In contrast, the more advanced, large pterodactyloid pterosaurs, such as Pteranodon, grew to adult size within the first year of life. Additionally, pterodactyloids had determinate growth, meaning that the animals reached a fixed maximum adult size and stopped growing.
Comparisons between the scleral rings of pterosaurs and modern birds and reptiles have been used to infer daily activity patterns of pterosaurs. The pterosaur genera Pterodactylus, Scaphognathus, and Tupuxuara have been inferred to be diurnal, Ctenochasma, Pterodaustro, and Rhamphorhynchus have been inferred to be nocturnal, and Tapejara has been inferred to be cathemeral, being active throughout the day for short intervals. As a result, the possibly fish-eating Ctenochasma and Rhamphorhynchus may have had similar activity patterns to modern nocturnal seabirds, and the filter-feeding Pterodaustro may have had similar activity patterns to modern anseriform birds that feed at night. The differences between activity patterns of the Solnhofen pterosaurs Ctenochasma, Rhamphorhynchus, Scaphognathus, and Pterodactylus may also indicate niche partitioning between these genera.
Because pterosaur anatomy has been so heavily modified for flight, and immediate transitional fossil predecessors have not so far been described, the ancestry of pterosaurs is not fully understood. Several hypotheses have been advanced, including links to the avemetatarsalian-like Scleromochlus, an ancestry among the basal archosauriforms, like Euparkeria, or among the protorosaurs.
Two researchers, Chris Bennett (1996) and David Peters (2000), have found pterosaurs to be protorosaurs or closely related to them. Peters used a technique called DGS, which involves applying the digital tracing features of photo editing software to images of pterosaur fossils. Bennett only recovered pterosaurs as close relatives of the protorosaurs after removing characteristics of the hind limb from his analysis, in an attempt to test the idea that these characters are the result of convergent evolution between pterosaurs and dinosaurs. However, subsequent analysis by Dave Hone and Michael Benton (2007) could not reproduce this result. Hone and Benton found pterosaurs to be closely related to dinosaurs even without hind limb characters. They also criticized previous studies by David Peters, raising questions about whether conclusions reached without access to the primary evidence, that is, pterosaur fossils, can be held to have the same weight as conclusions based strictly on first-hand interpretation. Hone and Benton concluded that, although more primitive pterosauromorphs are needed to clarify their relationships, pterosaurs are best considered archosaurs, and specifically ornithodirans, given current evidence. In Hone and Benton's analysis, pterosaurs are either the sister group of Scleromochlus or fall between it and Lagosuchus on the ornithodiran family tree. Sterling Nesbitt (2011) found strong support for a clade composed of Scleromochlus and pterosaurs. More recent studies on basal pterosaur hindlimb morphology seem to vindicate a connection to Scleromochlus. Like this archosaur, basal pterosaur lineages have plantigrade hindlimbs that show adaptations for saltation.
In phylogenetic taxonomy, the clade Pterosauria has usually been defined as node-based and anchored to several extensively studied taxa as well as those thought to be primitive. One 2003 study defined Pterosauria as "The most recent common ancestor of the Anurognathidae, Preondactylus and Quetzalcoatlus and all their descendants." However, these types of definition would inevitably leave any related species that are slightly more primitive out of the Pterosauria. To remedy this, a new definition was proposed that would anchor the name not to any particular species but to an anatomical feature, the presence of an enlarged fourth finger that supports a wing membrane. A broader clade, Pterosauromorpha, has been defined as all ornithodirans more closely related to pterosaurs than to dinosaurs.
The internal classification of pterosaurs has historically been difficult, because there were many gaps in the fossil record. Starting from the 21st century, new discoveries are now filling in these gaps and giving a better picture of the evolution of pterosaurs. Traditionally, they were organized into two suborders: the Rhamphorhynchoidea, a "primitive" group of long-tailed pterosaurs, and the Pterodactyloidea, "advanced" pterosaurs with short tails. However, this traditional division has been largely abandoned. Rhamphorhynchoidea is a paraphyletic (unnatural) group, since the pterodactyloids evolved directly from them and not from a common ancestor, so, with the increasing use of cladistics, it has fallen out of favor among most scientists.
The precise relationships between pterosaurs is still unsettled. Many studies of pterosaur relationships in the past have included limited data and were highly contradictory. However, newer studies using larger data sets are beginning to make things clearer. The cladogram (family tree) below follows a phylogenetic analysis presented by Andres & Myers in 2013.
It was once thought that competition with early bird species might have resulted in the extinction of many of the pterosaurs. Part of this is due to the fact it used to be thought that by the end of the Cretaceous, only large species of pterosaurs were present (no longer true; see below). The smaller species were thought to have become extinct, their niche filled by birds. However, pterosaur decline (if actually present) seems unrelated to bird diversity, as ecological overlap between the two groups appears to be minimal. In fact, at least some avian niches were reclaimed by pterosaurs prior to the KT event. At the end of the Cretaceous period, the Cretaceous–Paleogene extinction event, which wiped out all non-avian dinosaurs and most avian dinosaurs as well, and many other animals, seems also to have taken the pterosaurs.
In the early 2010s, several new pterosaur taxa were discovered dating to the Campanian/Maastrichtian, such as the ornithocheirids Piksi and "Ornithocheirus", possible pteranodontids and nyctosaurids, several tapejarids and the indeterminate non-azhdarchid Navajodactylus. Small azhdarchoid pterosaurs were also present in the Campanian. This suggests that late Cretaceous pterosaur faunas were far more diverse than previously thought, possibly not even having declined significantly from the early Cretaceous.
Small sized pterosaur species apparently were present in the Csehbánya Formation, indicating a higher diversity of Late Cretaceous pterosaurs than previously accounted for. The recent findings of a small cat-sized adult azhdarchid further indicate that small pterosaurs from the Late Cretaceous might actually have simply been rarely preserved in the fossil record, helped by the fact that there is a strong bias against terrestrial small sized vertebrates such as juvenile dinosaurs, and that their diversity might actually have been much larger than previously thought.
Pterosaurs have been a staple of popular culture for as long as their cousins the dinosaurs, though they are usually not featured as prominently in films, literature or other art. Additionally, while the depiction of dinosaurs in popular media has changed radically in response to advances in paleontology, a mainly outdated picture of pterosaurs has persisted since the mid 20th century.
While the generic term "pterodactyl" is often used to describe these creatures, the animals depicted frequently represent either Pteranodon or Rhamphorhynchus, or a fictionalized hybrid of the two. Many children's toys and cartoons feature "pterodactyls" with Pteranodon-like crests and long, Rhamphorhynchus-like tails and teeth, a combination that never existed in nature. However, at least one type of pterosaur did have the Pteranodon-like crest and teeth—for example, the Ludodactylus, a name that means "toy finger" for its resemblance to old, inaccurate children's toys. Also, some depictions of pterosaurs incorrectly identify them as "birds", when in real life they were flying reptiles, and birds are actually theropod dinosaurs.
Pterosaurs were used in fiction in Arthur Conan Doyle's 1912 novel The Lost World, and subsequent 1925 film adaptation. They have been used in a number of films and television programs since, including the 1933 film King Kong, and 1966's One Million Years B.C.. In the latter, animator Ray Harryhausen had to add inaccurate bat-like wing fingers to his stop motion models in order to keep the membranes from falling apart, though this particular error was common in art even before the film was made. The Japanese character Rodan, a fictional giant monster (or kaiju) which first appeared in the 1956 film Rodan, is portrayed as an enormous, irradiated species of Pteranodon. Rodan has appeared in multiple Godzilla films released during the 1960s, 1970s, 1990s, and 2000s, and also appeared in the 2019 American-produced film Godzilla: King of the Monsters.
After the 1960s, Pterosaurs remained mostly absent from notable American film appearances until 2001, with Jurassic Park III. However, paleontologist Dave Hone has noted that, even after the 40 intervening years, the pterosaurs in this film had not been significantly updated to reflect modern research. Among the errors he noted as persisting from the 1960s to the 2000s, were teeth even in toothless species (the Jurassic Park III pterosaurs were intended to be Pteranodon, which translates as "toothless wing"), nesting behavior that was known to be inaccurate by 2001, and leathery wings, rather than the taut membranes of muscle fiber that was actually present and required for pterosaur flight.
In most media appearances, pterosaurs are most often depicted as piscivores, a diet only a few pterosaur groups actually had in reality. When not shown as piscivores, they are also often shown as aerial predators similar to birds of prey, grasping human victims with their taloned feet. This is impossible as no pterosaur species known so far possesses prehensile feet; all known pterosaurs have flat, plantigrade feet with no opposable toes, often poorly muscled and, in the case of pteranodontians, generally proportionally small. However, some pterosaurs may have had raptorial tendencies; Thalassodromeus possesses powerful jaws akin to those of phorusrhacids, and Hatzegopteryx's short neck and more powerful jaws have been interpreted as a speciation on larger prey.
Campylognathoides ("curved jaw", Strand 1928) is a genus of pterosaur, discovered in the Württemberg Lias deposits (dated to the early Toarcian age) of Germany; this first specimen consisted however only of wing fragments. Further better preserved specimens were found in the Holzmaden shale: basing on these specimens Felix Plieninger erected a new genus.Eudimorphodontidae
Eudimorphodontidae is an extinct family of early pterosaurs from the Late Triassic (early Norian to Rhaetian age) of Europe. It was named by Peter Wellnhofer in 1978 to include Eudimorphodon ranzii. Some phylogenetic analyses suggested that Eudimorphodontidae is a junior synonym of Campylognathoididae, however more comprehensive analyses found Eudimorphodontidae to be basal to Macronychoptera that includes Campylognathoididae and more derived pterosaurs (Breviquartossa). Wang et al. (2009) found Eudimorphodontidae to include six species (the monospecific Peteinosaurus, Raeticodactylus and Caviramus, and three species of Eudimorphodon), but they didn't defined the clade. Brian Andres (2010, in press) define Eudimorphodontidae and found Peteinosaurus to be most closely related to it. Furthermore, he found monophyletic Eudimorphodon clade (unlike Wang et al., 2009 and Dalla Vecchia, 2009), and defined two subfamilies within Eudimorphodontidae. The Eudimorphodontinae includes all taxa more closely related to Eudimorphodon ranzii than to Raeticodactylus filisurensis while the Raeticodactylinae includes all taxa more closely related to Raeticodactylus filisurensis than to Eudimorphodon ranzii. More recently, Raeticodactylus and Caviramus were moved into their own family, Raeticodactylidae. The below cladogram follows that analysis.Fenghuangopterus
Fenghuangopterus is a genus of basal pterosaur that lived in northeastern China during the Middle Jurassic.
The type species Fenghuangopterus lii was in 2010 described and named by Lü Junchang et al. The generic name is derived from the Fenghuang Mountain and a Latinised Ancient Greek pteron, "wing". The specific name honours Li Xiumei, who donated the fossil. It is known from a single relatively complete, though badly crushed, fossil skeleton, holotype CYGB-0037, recovered from the Tiaojishan Formation of Liaoning Province, about 160 million years old. It is a member of the rhamphorhynchid subfamily Scaphognathinae, which had previously been known only from the Late Jurassic and includes the close relatives Scaphognathus, Sordes and Harpactognathus.Harpactognathus
Harpactognathus (meaning "seizing/grasping jaw") was a genus of pterosaur found in the Late Jurassic-age Morrison Formation of Albany County, Wyoming, United States. It is based on NAMAL 101, a partial skull consisting of the snout, recovered from near Bone Cabin Quarry in 1996. The species name honors the discoverer, Joe Gentry, a volunteer for the Western Paleontological Laboratories, in Lehi, Utah.Its describers found it to be most similar to Scaphognathus among pterosaurs, albeit substantially larger (estimated skull length of 280–300 mm (11–12 in), estimated wingspan of at least 2.5 m (8.2 ft)). Because of the similarity, Harpactognathus was assigned to the subfamily Scaphognathinae of the family Rhamphorhynchidae. This genus is also notable for having a low bony crest running all the way to the tip of the beak (pterosaur bone crests usually do not reach the tip) and for being the oldest known Morrison Formation pterosaur, having been found in the Salt Wash Member (Kimmeridgian).Istiodactylus
Istiodactylus is a genus of pterosaur that lived during the Early Cretaceous period, about 120 million years ago. The first fossil was discovered on the English Isle of Wight in 1887, and in 1901 became the holotype specimen of a new species, O. latidens (Latin for "wide tooth"), in the genus Ornithodesmus. This species was moved to its own genus, Istiodactylus, in 2001; this name is Greek for "sail finger". More specimens were described in 1913, and Istiodactylus was the only pterosaur known from three-dimensionally preserved fossils for much of the 20th century. In 2006, a species from China, I. sinensis, was assigned to Istiodactylus, but it has since been found to belong to a different genus.
Istiodactylus was a large pterosaur; estimates of its wingspan range from 4.3 to 5 metres (14 to 16 ft). Its skull was about 45 centimetres (18 in) long, and was relatively short and broad for a pterosaur. The front of the snout was low and blunt, and bore a semicircle of 48 teeth. The triangular teeth were closely spaced, interlocked, and formed a "razor-edged" outline. The lower jaw also had a tooth-like projection that occluded with the teeth. The skull had a very large naso-antorbital opening (which combined the antorbital fenestra and the opening for the bony nostril) and a slender eye socket. Some of the vertebrae were fused into a notarium, to which the shoulder blades connected. It had very large forelimbs, with a wing-membrane distended by a long wing-finger, but the hindlimbs were very short.
Until the 21st century, Istiodactylus was the only known pterosaur of its kind, and was placed in its own family, Istiodactylidae, within the group Ornithocheiroidea. Istiodactylus differed from other istiodactylids in having a proportionally shorter skull. The distinctive teeth of Istiodactylus indicate that it was a scavenger that may have used its teeth to sever morsels from large carcasses in the manner of a cookie cutter. The wings of Istiodactylus may have been adapted for soaring, which would have helped it find carcasses before terrestrial carnivores. Istiodactylus is known from the Wessex Formation and the younger Vectis Formation, which represent river and coastal environments that were shared with various pterosaurs, dinosaurs, and other animals.Jianchangnathus
Jianchangnathus is an extinct genus of basal pterosaur from the Middle Jurassic Tiaojishan Formation of northeastern China.Jianchangopterus
Jianchangopterus is a genus of scaphognathine rhamphorhynchid pterosaur from the Middle Jurassic of western Liaoning, China. Jianchangopterus is known from a nearly complete skeleton with skull preserved. It was collected from the Tiaojishan Formation. It was first named (after Jianchang County) by Lü Junchang and Bo Xue in 2011 and the type species is Jianchangopterus zhaoianus.List of pterosaur genera
This list of pterosaurs is a comprehensive listing of all genera that have ever been included in the order Pterosauria, excluding purely vernacular terms. The list includes all commonly accepted genera, but also genera that are now considered invalid, doubtful (nomen dubium), or were not formally published (nomen nudum), as well as junior synonyms of more established names, and genera that are no longer considered pterosaurian. The list currently includes 228 genera.Nesodactylus
Nesodactylus was a genus of "rhamphorhynchoid" pterosaur from the middle-late Oxfordian age Upper Jurassic Jagua Formation of Pinar del Río, western Cuba.
Its remains were collected but not prepared by Barnum Brown in 1918, from rocks better known for their fossils of marine life. When seven black chalkstone blocks were prepared from 1966 by Richard Lund by dissolving the substrate in acid, this revealed the remains of a pterosaur.
Ned Colbert described and named the genus in 1969. The type species is Nesodactylus hesperius. The genus name is derived from Greek nesos, "island" and daktylos, "finger", a reference to the island of Cuba and the typical wing finger of pterosaurs. The specific name means "western", from Greek hesperios.
The genus is based on holotype AMNH 2000, a partial skeleton including a skull fragment, numerous vertebrae from all parts of the spine and tail, zygapophyses (interpreted by Colbert as ossified tendons) on the tail, the pectoral girdle and a very deeply keeled sternum, arms and partial hands, part of the pelvis, parts of both femorae, partial metatarsals, and ribs. The specimen was disarticulated but associated and not very compressed; during the preparation from the limestone with acid, the bones were not completely removed.
Colbert found Nesodactylus to have had longer wings and more robust limbs and longer legs than related Rhamphorhynchus, although of a similar size and overall anatomy. He classified it as a rhamphorhynchid and more precisely as a member of the Rhamphorhynchinae.In 1977 James A. Jensen and John Ostrom by mistake referred to it as Nesodon (1977). Although there is little overlapping material with contemporaneous Cacibupteryx, the two are clearly different based on details of the elbow and quadrate. At least one recent review suggests it was a rhamphorhynchine, while another does not classify it.Novialoidea
Novialoidea (meaning "new wings") is an extinct clade of macronychopteran pterosaurs that lived from the latest Early Jurassic to the latest Late Cretaceous (early Toarcian to late Maastrichtian age), their fossils having been found on all continents except Antarctica. It was named by Alexander Wilhelm Armin Kellner in 2003 as a node-based taxon consisting of the last common ancestor of Campylognathoides, Quetzalcoatlus and all its descendants. This name was derived from Latin novus "new", and ala, "wing", in reference to the wing synapomorphies that the members of the clade possess. Unwin (2003) named Lonchognatha in the same issue of the journal that published Novialoidea (Geological Society of London, Special Publications 217) and defined it as Eudimorphodon ranzii, Rhamphorhynchus muensteri, their most recent common ancestor and all its descendants (as a node-based taxon). Under Unwin's and Kellner's phylogenetic analyses (where Eudimorphodon and Campylognathoides form a family that basal to both Rhamphorhynchus and Quetzalcoatlus), and because Novialoidea was named first (in pages 105-137, while Lonchognatha was named in pages 139-190), Lonchognatha is an objective junior synonym of the former. However, other analyses find Lonchognatha to be valid (Andres et al., 2010) or synonymous with the Pterosauria (Andres, 2010 and Andres, in press).Pteranodon
Pteranodon (; from Greek πτερόν ( pteron, "wing") and ἀνόδων (anodon, "toothless") is a genus of pterosaur that included some of the largest known flying reptiles, with wingspans over 7 meters (23 feet). They lived during the late Cretaceous geological period of North America in present-day Kansas, Alabama, Nebraska, Wyoming, and South Dakota. More fossil specimens of Pteranodon have been found than any other pterosaur, with about 1,200 specimens known to science, many of them well preserved with nearly complete skulls and articulated skeletons. It was an important part of the animal community in the Western Interior Seaway.Pteranodon were pterosaurs, not dinosaurs. By definition, all dinosaurs belong to one of the two groups within Dinosauria, i.e. Saurischia or Ornithischia. As such, this excludes pterosaurs. Nonetheless, Pteranodon are frequently featured in dinosaur media and are strongly associated with dinosaurs by the general public. While not dinosaurs, they form a sister clade to dinosaurs within the clade Avemetatarsalia.Pterodactylus
Pterodactylus (meaning "winged finger") is an extinct genus of pterosaurs, whose members are commonly known as pterodactyls ( ). It is thought to contain only a single species, Pterodactylus antiquus, the first pterosaur species to be named and identified as a flying reptile.
The fossil remains of this species have been found primarily in the Solnhofen limestone of Bavaria, Germany, dated to the late Jurassic Period (early Tithonian), about 150.8–148.5 million years ago, though more fragmentary remains have been tentatively identified from elsewhere in Europe and in Africa.
It was a carnivore and probably preyed upon fish and other small animals. Like all pterosaurs, Pterodactylus had wings formed by a skin and muscle membrane stretching from its elongated fourth finger to its hind limbs. It was supported internally by collagen fibres and externally by keratinous ridges.Qinglongopterus
Qinglongopterus is a genus of rhamphorhynchine rhamphorhynchid pterosaur from the Middle/Upper Jurassic of Mutoudeng, Qinglong County, Hebei Province, China. Qinglongopterus is known from only one specimen; D3080/3081, collected from the Tiaojishan Formation, a skeleton with a skull. It was first named by Lü Junchang et al. in 2012 and the type species is Qinglongopterus guoi.Quetzalcoatlus
Quetzalcoatlus northropi is a pterosaur known from the Late Cretaceous of North America (Maastrichtian stage) and one of the largest known flying animals of all time. It is a member of the family Azhdarchidae, a family of advanced toothless pterosaurs with unusually long, stiffened necks. Its name comes from the Mesoamerican feathered serpent god, Quetzalcoatl.Rhamphorhynchidae
Rhamphorhynchidae is a group of early "rhamphorhynchoid" pterosaurs named after Rhamphorhynchus, that lived in the Late Jurassic. The family Rhamphorhynchidae was named in 1870 by Harry Govier Seeley.Rhamphorhynchus
Rhamphorhynchus (, "beak snout") is a genus of long-tailed pterosaurs in the Jurassic period. Less specialized than contemporary, short-tailed pterodactyloid pterosaurs such as Pterodactylus, it had a long tail, stiffened with ligaments, which ended in a characteristic diamond-shaped vane. The jaws of Rhamphorhynchus housed needle-like teeth, which were angled forward, with a curved, sharp, beak-like tip lacking teeth, indicating a diet mainly of fish; indeed, fish and cephalopod remains are frequently found in Rhamphorhynchus' abdominal contents, as well as in their coprolites.Although fragmentary fossil remains possibly belonging to Rhamphorhynchus have been found in England, Tanzania, and Spain, the best preserved specimens come from the Solnhofen limestone of Bavaria, Germany. Many of these fossils preserve not only the bones but impressions of soft tissues, such as wing membranes. Scattered teeth believed to belong to Rhamphorhynchus have been found in Portugal as well.Scaphognathus
Scaphognathus was a pterosaur that lived around Germany during the Late Jurassic. It had a wingspan of 0.9 m (3 ft).Sericipterus
Sericipterus is an extinct genus of rhamphorhynchid pterosaur. It is known from the Late Jurassic (early Oxfordian age) Shishugou Formation in Xinjiang, China.
The genus was named and described in 2010 by Brian Andres, James Matthew Clark and Xu Xing. The type species is Sericipterus wucaiwanensis. The generic name is derived from Latin sericum, "silk", a reference to the Silk Route, and from a Latinised Greek pteron, "wing". The specific name refers to the Wucaiwan area, itself meaning "five-colour bay" because of the many-coloured layers.
The holotype specimen, IVPP V14725, consists of partly crushed, disarticulated bones that are largely preserved three-dimensionally. The wingspan has been estimated to have been at least 1.73 metres (5 ft 8 in). The skull of Sericipterus is similar to those of the "rhamphorhynchoids" (i.e. basal pterosaurs) Angustinaripterus and Harpactognathus. It had three bony crests: a low crest on the snout, a short low parietal crest on top of the skull and a short traverse crest connected to the front edge of the latter. The parietal crest is the first reported for a non-pterodactyloid pterosaur. The same is true for the rosette, bearing two pairs of forward pointing laniaries, formed by a narrowing of the snout behind these long fangs. Another probably five pairs of teeth were present in a more posterior position in the upper jaws. The number in the lower jaw is unknown. Except for the first rather straight pair, the teeth were recurved, sharply pointed, covered with smooth enamel and circular in cross-section but equipped with two keels providing cutting edges.
Sericipterus has, after a comprehensive new cladistic analysis of the Pterosauria, been placed as the sister taxon of Angustinaripterus in the Rhamphorhynchinae, a clade which also includes other large-bodied "rhamphorhynchoids", living inland as predators of small tetrapods and preserved in terrestrial sediments.Timeline of pterosaur research
This timeline of pterosaur research is a chronologically ordered list of important fossil discoveries, controversies of interpretation, and taxonomic revisions of pterosaurs, the famed flying reptiles of the Mesozoic era. Although pterosaurs went extinct millions of years before humans evolved, humans have coexisted with pterosaur fossils for millennia. Before the development of paleontology as a formal science, these remains would have been interpreted through a mythological lens. Myths about thunderbirds told by the Native Americans of the modern western United States may have been influenced by observations of Pteranodon fossils. These thunderbirds were said to have warred with water monsters, which agrees well with the co-occurrence of Pteranodon and the ancient marine reptiles of the seaway over which it flew.The formal study of pterosaurs began in the late 18th century when naturalist Cosimo Alessandro Collini of Mannheim, Germany published a description of an unusual animal with long arms, each bearing an elongated finger. He recognized that this long finger could support a membrane like that of a bat wing, but because the unnamed creature was found in deposits that preserve marine life he concluded that these strange arms were used as flippers. The creature was restudied again in the very early 19th century by French anatomist Georges Cuvier, who recognized both that the creature was a reptile and that its "flippers" were wings. He called the creature the Ptero-dactyle, a name since revised to Pterodactylus.Although Cuvier's interpretation later became the consensus, it was just one of many early interpretations of the creature and its relatives, including that they were bats, strange birds, or the primordial handiwork of Satan himself. Similar animals like the long-tailed Rhamphorhynchus and Gnathosaurus were soon discovered around Europe and it became obvious that earth was once home to a diverse group of flying reptiles. The British anatomist Sir Richard Owen dubbed this vanished order the Pterosauria. Soon after, he described Britain's own first pterosaur, Dimorphodon. Later in the 19th century pterosaurs were discovered in North America as well, the first of which was a spectacular animal named Pteranodon by paleontologist Othniel Charles Marsh.Various aspects of pterosaur biology invited controversy from the beginning. Samuel Thomas von Soemmering ignited a multi-century debate over how pterosaurs walked on the ground by suggesting they crawled on all fours like bats. August Quenstedt, by contrast, argued that they walked on their hind limbs. In the early 20th century, Hankin and Watson in the first major study of pterosaur flight biomechanics concluded that on the ground these reptiles were altogether helpless and could only scoot along on their stomachs like penguins. The debate gained steam in 1957 when William Stokes reported unusual tracks left by a four-footed animal he suspected was a pterosaur walking along the ground. In 1984, Kevin Padian, who had recently argued that pterosaurs walked on their hind legs, dismissed Stokes's tracks as those of a crocodilian. However, in the mid-1990s, Jean-Michel Mazin and others reported that fossil footprints in Crayssac, France were similar to those reported by Stokes from the US. Mazin's tracks were more obviously pterosaurian in origin and settled the debate in favor of pterosaurs walking on all fours.Pterosaur paleontology continues to progress into the 21st century. In fact, according to David Hone the early 21st century has seen more progress in pterosaur paleontology than in "the preceding two centuries" combined. He compared this transformative period in pterosaur paleontology to the Dinosaur Renaissance of the 1970s. He also observed that roughly one-third of known pterosaurs were discovered during this brief interval. One of the most notable of these was Darwinopterus, whose body resembled the more primitive long-tailed "rhamphorynchoids", while its skull resembled those of the more advanced short-tailed pterodactyloids. These traits establish the species as an important transitional form, documenting one of the most important phases of pterosaur evolution. Another important new species is Faxinalipterus minima, which might well be the world's oldest pterosaur. The first confirmed pterosaur eggs were also reported from China during the early 21st century.