Pterodactylus antiquus

''Pterodactylus'' (from Greek () meaning 'winged finger') is an extinct genus of pterosaurs. It is thought to contain only a single species, ''Pterodactylus antiquus'', which was the first pterosaur to be named and identified as a flying reptile.

Fossil remains of ''Pterodactylus'' have primarily been found in the Solnhofen limestone of Bavaria, Germany, which dates from the Late Jurassic period (early Tithonian stage), about 150.8 to 148.5 million years ago. More fragmentary remains of ''Pterodactylus'' have tentatively been identified from elsewhere in Europe and in Africa.

''Pterodactylus'' was a generalist carnivore that probably fed on a variety of invertebrates and vertebrates. 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. ''Pterodactylus'' was a small pterosaur compared to other famous genera such as ''Pteranodon'' and ''Quetzalcoatlus'', and it also lived earlier, during the Late Jurassic period, while both ''Pteranodon'' and ''Quetzalcoatlus'' lived during the Late Cretaceous. ''Pterodactylus'' lived alongside other small pterosaurs such as the well-known '' Rhamphorhynchus'', as well as other genera such as '' Scaphognathus'', '' Anurognathus'' and '' Ctenochasma''. ''Pterodactylus'' is classified as an early-branching member of the ctenochasmatid lineage, within the pterosaur clade Pterodactyloidea.

Discovery and history

The type specimen of the animal now known as ''Pterodactylus antiquus'' was the first pterosaur fossil ever to be identified. The first ''Pterodactylus'' specimen was described by the Italian scientist in 1784, based on a fossil skeleton that had been unearthed from the Solnhofen limestone of Bavaria. Collini was the curator of the , or nature cabinet of curiosities (a precursor to the modern concept of the natural history museum), in the palace of Charles Theodore, Elector of Bavaria at Mannheim. The specimen had been given to the collection by Count around 1780, having been recovered from a lithographic limestone quarry in . The actual date of the specimen's discovery and entry into the collection is unknown however, and it was not mentioned in a catalogue of the collection taken in 1767, so it must have been acquired at some point between that date and its 1784 description by Collini. This makes it potentially the earliest documented pterosaur find; the "Pester Exemplar" of the genus '' Aurorazhdarcho'' was described in 1779 and possibly discovered earlier than the Mannheim specimen, but it was at first considered to be a fossilized crustacean, and it was not until 1856 that this species was properly described as a pterosaur by German paleontologist .

In his first description of the Mannheim specimen, Collini did not conclude that it was a flying animal. In fact, Collini could not fathom what kind of animal it might have been, rejecting affinities with the birds or the bats. He speculated that it may have been a sea creature, not for any anatomical reason, but because he thought the ocean depths were more likely to have housed unknown types of animals. The idea that pterosaurs were aquatic animals persisted among a minority of scientists as late as 1830, when the German zoologist Johann Georg Wagler published a text on "amphibians" which included an illustration of ''Pterodactylus'' using its wings as flippers. Wagler went so far as to classify ''Pterodactylus'', along with other aquatic vertebrates (namely plesiosaurs, ichthyosaurs, and monotremes), in the class Gryphi, between birds and mammals.

The German/French scientist Johann Hermann was the one who first stated that ''Pterodactylus'' used its long fourth finger to support a wing membrane. Back in March 1800, Hermann alerted the prominent French scientist Georges Cuvier to the existence of Collini's fossil, believing that it had been captured by the occupying armies of Napoleon and sent to the French collections in Paris (and perhaps to Cuvier himself) as war booty; at the time special French political commissars systematically seized art treasures and objects of scientific interest. Hermann sent Cuvier a letter containing his own interpretation of the specimen (though he had not examined it personally), which he believed to be a mammal, including the first known life restoration of a pterosaur. Hermann restored the animal with wing membranes extending from the long fourth finger to the ankle and a covering of fur (neither wing membranes nor fur had been preserved in the specimen). Hermann also added a membrane between the neck and wrist, as is the condition in bats. Cuvier agreed with this interpretation, and at Hermann's suggestion, Cuvier became the first to publish these ideas in December 1800 in a very short description. However, contrary to Hermann, Cuvier was convinced the animal was a reptile. The specimen had not in fact been seized by the French. Rather, in 1802, following the death of Charles Theodore, it was brought to Munich, where Baron Johann Paul Carl von Moll had obtained a general exemption of confiscation for the Bavarian collections. Cuvier asked von Moll to study the fossil but was informed it could not be found. In 1809 Cuvier published a somewhat longer description, in which he named the animal ''Petro-Dactyle'', this was a typographical error however, and was later corrected by him to ''Ptéro-Dactyle''. He also refuted a hypothesis by Johann Friedrich Blumenbach that it would have been a shore bird. Cuvier remarked: "It is not possible to doubt that the long finger served to support a membrane that, by lengthening the anterior extremity of this animal, formed a good wing."

Contrary to von Moll's report, the fossil was not missing; it was being studied by Samuel Thomas von Sömmerring, who gave a public lecture about it on December 27, 1810. In January 1811, von Sömmerring wrote a letter to Cuvier deploring the fact that he had only recently been informed of Cuvier's request for information. His lecture was published in 1812, and in it von Sömmerring named the species ''Ornithocephalus antiquus''. The animal was described as being both a bat, and a form in between mammals and birds, i.e. not intermediate in descent but in "affinity" or archetype. Cuvier disagreed, and the same year in his ''Ossemens fossiles'' provided a lengthy description in which he restated that the animal was a reptile. It was not until 1817 that a second specimen of ''Pterodactylus'' came to light, again from Solnhofen. This tiny specimen was that year described by von Sömmerring as '' Ornithocephalus brevirostris'', named for its short snout, now understood to be a juvenile character (this specimen is now thought to represent a juvenile specimen of a different genus, probably '' Ctenochasma''). He provided a restoration of the skeleton, the first one published for any pterosaur. This restoration was very inaccurate, von Sömmerring mistaking the long metacarpals for the bones of the lower arm, the lower arm for the humerus, this upper arm for the breast bone and this sternum again for the shoulder blades. Sömmerring did not change his opinion that these forms were bats and this "bat model" for interpreting pterosaurs would remain influential long after a consensus had been reached around 1860 that they were reptiles. The standard assumptions were that pterosaurs were quadrupedal, clumsy on the ground, furred, warmblooded and had a wing membrane reaching the ankle. Some of these elements have been confirmed, some refuted by modern research, while others remain disputed.

In 1815, the generic name ''Ptéro-Dactyle'' was latinized to ''Pterodactylus'' by Constantine Samuel Rafinesque. Unaware of Rafinesque's publication however, Cuvier himself in 1819 latinized the name ''Ptéro-Dactyle'' again to ''Pterodactylus'', but the specific name he then gave, ''longirostris'', has to give precedence to von Sömmerring's ''antiquus''. In 1888, English naturalist Richard Lydekker designated ''Pterodactylus antiquus'' as the type species of ''Pterodactylus'', and considered ''Ornithocephalus antiquus'' a synonym. He also designated specimen BSP AS.I.739 as the holotype of the genus.

Description

''Pterodactylus'' is known from over 30 fossil specimens, and though most belong to juveniles, many preserve complete skeletons. ''Pterodactylus antiquus'' was a relatively small pterosaur, with an estimated adult wingspan of about , based on the only known adult specimen, which is represented by an isolated skull. Other "species" were once thought to have been smaller. However, these smaller specimens have been shown to represent juveniles of ''Pterodactylus'', as well as its contemporary relatives including ''Ctenochasma'', '' Germanodactylus'', '' Aurorazhdarcho'', '' Gnathosaurus'', and hypothetically ''Aerodactylus'' if this genus is truly valid.

The skulls of adult ''Pterodactylus'' were long and thin, with about 90 narrow and conical teeth. The teeth extended back from the tips of both jaws, and became smaller farther away from the jaw tips, this was unlike the ones seen in most relatives, where teeth were absent in the upper jaw tip, and were relatively uniform in size. The teeth of ''Pterodactylus'' also extended farther back into the jaw compared to close relatives, and some were present below the front of the ''nasoantorbital fenestra'', which is the largest opening in the skull. Another autapomorphy that ''Pterodactylus'' has is that the skull and jaws were straight, which are unlike the upwardly curved jaws seen in the related ctenochasmatids.

''Pterodactylus'', like related pterosaurs, had a crest on its skull composed mainly of soft tissues. In adult ''Pterodactylus'', this crest extended between the back edge of the antorbital fenestra and the back of the skull. In at least one specimen, the crest had a short bony base, also seen in related pterosaurs like ''Germanodactylus''. Solid crests have only been found on large, fully adult specimens of ''Pterodactylus'', indicating that this was a display structure that became larger and more well developed as individuals reached maturity. In 2013, pterosaur researcher S. Christopher Bennett noted that other authors claimed that the soft tissue crest of ''Pterodactylus'' extended backward behind the skull; Bennett himself, however, didn't find any evidence for the crest extending past the back of the skull. Two specimens of ''P. antiquus'' (the holotype specimen BSP AS I 739 and the incomplete skull BMMS 7, the largest known skull of ''P. antiquus'') have a low bony crest on their skulls; in BMMS 7 it is 47.5 mm long (1.87 inches, more or less 24% of the estimated total length of its skull) and has a maximum height of 0.9 mm (0.035 inches) above the orbit. Several specimens previously referred to ''P. antiquus'' preserved evidence of the soft tissue extensions of these crests, including an "occipital lappet", a flexible, tab-like structure extending from the back of the skull. Most of these specimens have been reclassified in the related species ''Aerodactylus scolopaciceps'', which may however be nothing more than a junior synonym. Even if ''Aerodactylus'' were valid, at least one specimen with these features is still considered to belong to ''Pterodactylus'', BSP 1929 I 18, which has an occipital lappet similar to the proposed ''Aerodactylus'' definition, and also possesses a small triangular soft tissue crest with the peak of the crest positioned above the eyes.

Paleobiology

Life history

Like other pterosaurs (most notably '' Rhamphorhynchus''), ''Pterodactylus'' specimens can vary considerably based on age or level of maturity. Both the proportions of the limb bones, size and shape of the skull, and size and number of teeth changed as the animals grew. Historically, this has led to various growth stages (including growth stages of related pterosaurs) being mistaken for new species of ''Pterodactylus''. Several detailed studies using various methods to measure growth curves among known specimens have suggested that there is actually only one valid species of ''Pterodactylus'', ''P. antiquus''.

The youngest immature specimens of ''Pterodactylus antiquus'' (alternately interpreted as young specimens of the distinct species ''P. kochi'') have a small number of teeth, as few as 15 in some, and the teeth have a relatively broad base. The teeth of other ''P. antiquus'' specimens are both narrower and more numerous (up to 90 teeth are present in several specimens).

''Pterodactylus'' specimens can be divided into two distinct year classes. In the first year class, the skulls are only in length. The second year class is characterized by skulls of around long, but are still immature however. These first two size groups were once classified as juveniles and adults of the species ''P. kochi'', until further study showed that even the supposed "adults" were immature, and possibly belong to a distinct genus. A third year class is represented by specimens of the "traditional" ''P. antiquus'', as well as a few isolated, large specimens once assigned to ''P. kochi'' that overlap ''P. antiquus'' in size. However, all specimens in this third year class also show sign of immaturity. Fully mature ''Pterodactylus'' specimens remain unknown, or may have been mistakenly classified as a different genus.

Growth and breeding seasons

The distinct year classes of ''Pterodactylus antiquus'' specimens show that this species, like the contemporary ''Rhamphorhynchus muensteri'', likely bred seasonally and grew consistently during its lifetime. A new generation of 1st year class ''P. antiquus'' would have been produced seasonally, and reached 2nd-year size by the time the next generation hatched, creating distinct 'clumps' of similarly-sized and aged individuals in the fossil record. The smallest size class probably consisted of individuals that had just begun to fly and were less than one year old. The second year class represents individuals one to two years old, and the rare third year class is composed of specimens over two years old. This growth pattern is similar to modern crocodilians, rather than the rapid growth of modern birds.

Daily activity patterns

Comparisons between the scleral rings of ''Pterodactylus antiquus'' and modern birds and reptiles suggest that it may have been diurnal. This may also indicate niche partitioning with contemporary pterosaurs inferred to be nocturnal, such as ''Ctenochasma'' and ''Rhamphorhynchus''.

Diet

Based on the shape, size, and arrangement of its teeth, ''Pterodactylus'' has long been recognized as a carnivore specializing in small animals. A 2020 study of pterosaur tooth wear supported the hypothesis that ''Pterodactylus'' preyed mainly on invertebrates and had a generalist feeding strategy, indicated by a relatively high bite force.Bestwick, J., Unwin, D.M., Butler, R.J. et al. Dietary diversity and evolution of the earliest flying vertebrates revealed by dental microwear texture analysis. Nat Commun 11, 5293 (2020). https://doi.org/10.1038/s41467-020-19022-2

Paleoecology

Specimens of ''Pterodactylus'' have been found mainly in the Solnhofen limestone (geologically known as the Altmühltal Formation) of Bavaria, Germany. The main composition of this formation is fine-grained limestone that originated mainly from the nearby towns Solnhofen and Eichstätt, which is formed by mud silt deposits. The Solnhofen Limestone is a diverse Lagerstätte that contains a wide range of different creatures, including highly detailed fossilized imprints of soft bodied organisms such as jellyfishes. Abundant specimens of pterosaurs similar to ''Pterodactylus'' were also found within the formation, these include the rhamphorhynchids ''Rhamphorhynchus'' and '' Scaphognathus'', several gallodactylids such as ''Aerodactylus'', '' Ardeadactylus'', ''Aurorazhdarcho'' and ''Cycnorhamphus'', the ctenochasmatids ''Ctenochasma'' and ''Gnathosaurus'', the anurognathid '' Anurognathus'', the germanodactylid ''Germanodactylus'', as well as the basal euctenochasmatian '' Diopecephalus''. Fossil remains of the dinosaurs ''Archaeopteryx'' and '' Compsognathus'' were also found within the limestone, these specimens were related to early evolution of feathers, since they were some of the only ones that had them during the Jurassic period. Various lizard remains were also found alongside those of ''Pterodactylus'', with several specimens assigned to '' Ardeosaurus'', ''Bavarisaurus''. Crocodylomorph specimens were widely distributed within the fossil site, most were assigned to the metriorhynchid genera ''Cricosaurus'', '' Dakosaurus'', '' Geosaurus'' and '' Rhacheosaurus''. These genera are colloquially called as marine or sea crocodiles due to their similar built. The turtle genera '' Eurysternum'' and '' Paleomedusa'' were also found within the formation. Fossils of the ichthyosaur '' Aegirosaurus'' also appeared to be present in the site, as well as fish remains, with many specimens assigned to ray-finned fishes such as the halecomorphs '' Lepidotes'', ''Propterus'', ''Gyrodus'', '' Mesturus'', ''Proscinetes'', ''Caturus'', ''Ophiopsis'' and '' Ophiopsiella'', the pachycormids ''Asthenocormus'', ''Hypsocormus'' and ''Orthocormus'', as well as the aspidorhynchid '' Aspidorhynchus'', and the ichthyodectid '' Thrissops''.

Classification

Initial classifications for ''Pterodactylus'' started when paleontologist Hermann von Meyer used the name Pterodactyli to contain ''Pterodactylus'' and other pterosaurs known at the time. This was emended to the family Pterodactylidae by Prince Charles Lucien Bonaparte in 1838. However, this group has more recently been given several competing definitions.

Beginning in 2014, researchers Steven Vidovic and David Martill constructed an analysis in which several pterosaurs traditionally thought of as archaeopterodactyloids closely related to the ctenochasmatoids may have been more closely related to the more advanced dsungaripteroids, or in some cases, fall outside both groups. Their conclusion was published in 2017, in which they placed ''Pterodactylus'' as a basal member of the suborder Pterodactyloidea.

As illustrated below, the results of a different topology are based on a phylogenetic analysis made by Longrich, Martill, and Andres in 2018. Unlike the previous results above, they placed ''Pterodactylus'' within the clade Euctenochasmatia, resulting in a more derived position.

Formerly assigned species

Numerous species have been assigned to ''Pterodactylus'' in the years since its discovery. In the first half of the 19th century any new pterosaur species would be named ''Pterodactylus'', which thus became a " wastebasket taxon". Even after clearly different forms had later been given their own generic name, new species would be created from the very productive sites, throughout Europe and North America, often based on only slightly different material.

The earliest reassignments of pterosaur species to ''Pterodactylus'' started in 1825, with the description of ''Rhamphorhynchus''; fossil collector Georg Graf zu Münster alerted the German paleontologist Samuel Thomas von Sömmerring about several distinct fossil specimens, Sömmerring thought that they belonged to an ancient bird. Further fossil preparations had uncovered teeth, to which Graf zu Münster created a skull cast. He later sent the cast to Professor Georg August Goldfuss, who recognized it as a pterosaur, specifically a species of ''Pterodactylus''. At the time however, most paleontologists incorrectly consider the genus ''Ornithocephalus'' () to be the valid name for ''Pterodactylus'', and therefore the specimen found was named as ''Ornithocephalus Münsteri'', which was first mentioned by Graf zu Münster himself. Another specimen was found and described by Graf zu Münster in 1839, he assigned this specimen to a new separate species called ''Ornithocephalus longicaudus''; the specific name means 'long tail', in reference to the animal's tail size. German paleontologist Hermann von Meyer in 1845 officially emended that the genus ''Pterodactylus'' had priority over ''Ornithocephalus'', so he reassigned the species ''O. münsteri'' and ''O. longicaudus'' into ''Pterodactylus münsteri'' and ''Pterodactylus longicaudus''. In 1846, von Meyer created the new species ''Pterodactylus gemmingi'' based on long-tailed remains; the specific name honors the fossil collector Carl Eming von Gemming. Later, in 1847, von Meyer finally erected the generic name ''Rhamphorhynchus'' () due to the distinctively long tails seen in the specimens found, which are much longer than those seen in ''Pterodactylus''. He assigned the species ''P. longicaudus'' as the type species of ''Rhamphorhynchus'', which resulted in a new combination called ''Rhamphorhynchus longicaudus''. The species ''R. münsteri'' was later changed to ''R. muensteri'' by Lydekker in 1888, due to the ICZN rule that prohibits non-standard Latin characters, such as ''ü'', in scientific names.

Beginning in 1846, many pterosaur specimens were found near the village of Burham in Kent, England by British paleontologists James Scott Bowerbank and Sir Richard Owen. Bowerbank had assigned fossil remains to two new species; the first was named in 1846 as ''Pterodactylus giganteus''; the specific name means 'the gigantic one' in Latin, in reference to the large size of the remains, and the second species was named in 1851 as ''Pterodactylus cuvieri'', in honor of the French scientist Georges Cuvier. Later in 1851, Owen named and described new pterosaur specimens that have been found yet again in England. He assigned these specimens to a new species called ''Pterodactylus compressirostris''.Owen, R. (1851). Monograph on the fossil Reptilia of the Cretaceous Formations. ''The Palaeontographical Society'' 5(11):1–118. In 1914 however, paleontologist Reginald Hooley redescribed ''P. compressirostris'', to which he erected the genus '' Lonchodectes'' (), and therefore made ''P. compressirostris'' the type species, and created the new combination ''L. compressirostris''. In a 2013 review, ''P. giganteus'' and ''P. cuvieri'' were reassigned to new genera; ''P. giganteus'' was reassigned to a genus called ''Lonchodraco'' ('lance dragon'), which resulted in a new combination called ''L. giganteus'', and ''P. cuvieri'' was reassigned to the new genus ''Cimoliopterus'' ('chalk wing'), creating ''C. cuvieri''. Back in 1859, Owen had found remains the front part of a snout in the Cambridge Greensand, and assigned it into the species ''Pterodactylus segwickii''; in honor of Adam Sedgwick, a British geologist. This species however, was reassigned to the genus '' Camposipterus'' in 2013, therefore creating the new combination ''Camposipterus segwickii''. Later, in 1861, Owen had uncovered multiple distinctively looking fossil remains yet again in the Cambridge Greensand, these were assigned to a new species named ''Pterodactylus simus'', though the British paleontologist Harry Govier Seeley had created a separate generic name called '' Ornithocheirus'', and reassigned ''P. simus'' as the type species, which created the combination ''Ornithocheirus simus''. Between the years 1869 and 1870, Seeley had reassigned many pterosaur species into ''Ornithocheirus'', while also creating several new species. Many of these species however, are now reclassified to other genera, or considered . In 1874, further specimens were found in England, again by Owen, these ones were assigned to a new species called ''Pterodactylus sagittirostris'', this species however, was reassigned to the genus ''Lonchodectes'' in 1914 by Hooley, which resulted in an ''L. sagittirostris''. This conclusion was revised by Rigal ''et al.'' in 2017, who disagreed with Hooley's reassignment, and therefore created the genus '' Serradraco'', which afterwards resulted in a new combination called ''S. sagittirostris''.

Assigning new pterosaur species to ''Pterodactylus'' was not only common in Europe, but also in North America; paleontologists such as Othniel Charles Marsh in 1871 for example, described several toothless pterosaur specimens, which were accompanied by teeth that belonged to the fish '' Xiphactinus'', which Marsh assumed that these teeth belonged to the pterosaur specimens he found, since all pterosaurs discovered at the time had teeth. He then assigned these specimens to a new species called ''"Pterodactylus oweni"'', but this was changed to ''Pterodactylus occidentalis'' because ''"P. oweni"'' was found to have been preoccupied by a pterosaur species described with the same name back in 1864 by Seeley. In 1872, American paleontologist Edward Drinker Cope also found various pterosaur specimens in North America, he assigned these to two new species known as ''Ornithochirus umbrosus'' and ''Ornithochirus harpyia'', Cope attempted to assign the specimens he found to the genus ''Ornithocheirus'', but misspelled forgetting the 'e'. In 1875 however, Cope reassigned the species ''O. umbrosus'' and ''O. harpyia'' into ''Pterodactylus umbrosus'' and ''Pterodactylus harpyia'', though these species had been considered ever since. Paleontologist Samuel Wendell Williston unearthed the first skull of the pterosaur, and found that the animal was toothless, this made Marsh create the genus ''Pteranodon'' (lit. 'toothless wing'), and therefore reassigned all the American pterosaur species, including the ones that he named, from ''Pterodactylus'' to ''Pteranodon''.

Later, in the 1980s, subsequent revisions by Peter Wellnhofer had reduced the number of recognized species to about half a dozen. Many species assigned to ''Pterodactylus'' had been based on juvenile specimens, and subsequently been recognized as immature individuals of other species or genera. By the 1990s it was understood that this was even true for part of the remaining species. ''P. elegans'', for example, was found by numerous studies to be an immature ''Ctenochasma''. Another species of ''Pterodactylus'' originally based on small, immature specimens was ''P. micronyx''. However, it has been difficult to determine exactly of what genus and species ''P. micronyx'' might be the juvenile form. Stéphane Jouve, Christopher Bennett and others had once suggested that it probably belonged either to '' Gnathosaurus subulatus'' or one of the species belonging to ''Ctenochasma'', though after additional research Bennett assigned it to the genus ''Aurorazhdarcho''. Another species with a complex history is ''P. longicollum'', named by von Meyer in 1854, based on a large specimen with a long neck and fewer teeth. Many researchers, including David Unwin, have found ''P. longicollum'' to be distinct from ''P. kochi'' and ''P. antiquus''. Unwin found ''P. longicollum'' to be closer to ''Germanodactylus'' and therefore requiring a new genus name. It has sometimes been placed in the genus ''Diopecephalus'' because Harry Govier Seeley based this genus partly on the ''P. longicollum'' material. However, it was shown by Bennett that the type specimen later designated for ''Diopecephalus'' was a fossil belonging to ''P. kochi'', and no longer thought to be separate from ''Pterodactylus''. ''Diopecephalus'' is therefore a synonym of ''Pterodactylus'', and as such is unavailable for use as a new genus for ''"P." longicollum''. ''"P." longicollum'' was eventually made the type species of a separate genus ''Ardeadactylus''.

Controversial species

The only well-known and well-supported species left by the first decades of the 21st century were ''P. antiquus'' and ''P. kochi''. However, most studies between 1995 and 2010 found little reason to separate even these two species, and treated them as synonymous. More recent studies of pterosaur relationships have found anurognathids and pterodactyloids to be sister groups, which would limit the more inclusive group Caelidracones to just two clades. In 1996, Bennett suggested that the differences between specimens of ''P. kochi'' and ''P. antiquus'' could be explained by differences in age, with ''P. kochi'' (including specimens alternately classified in the species ''P. scolopaciceps'') representing an immature growth stage of ''P. antiquus''. In a 2004 paper, Jouve used a different method of analysis and recovered the same result, showing that the "distinctive" features of ''P. kochi'' were age-related, and using mathematical comparison to show that the two forms are different growth stages of the same species. An additional review of the specimens published in 2013 demonstrated that some of the supposed differences between ''P. kochi'' and ''P. antiquus'' were due to measurement errors, further supporting their synonymy.

By the 2010s, a large body of research had been developed based on the idea that ''P. kochi'' and ''P. scolopaciceps'' were early growth stages of ''P. antiquus''. However, in 2014, two scientists began publishing research that challenged this paradigm. Steven Vidovic and David Martill concluded that differences between specimens of ''P. kochi'', ''P. scolopaciceps'', and ''P. antiquus'', such as different lengths of neck vertebrae, thinner or thicker teeth, more rounded skulls, and how far the teeth extended back in the jaws, were significant enough to separate them into three distinct species. Vidovic and Martill also performed a phylogenetic analysis which treated all relevant specimens as distinct units, and found that the ''P. kochi'' type specimen did not form a natural group with that of ''P. antiquus''. They concluded that the genus ''Diopecephalus'' could be returned to use to distinguish ''"P". kochi'' from ''P. antiquus''. They named the new genus ''Aerodactylus'' for ''P. scolopaciceps'' as well. So, what Bennett considered early growth stages of one species, Vidovic and Martill considered representatives of new species.

In 2017, Bennett challenged this hypothesis, he claimed that while Vidovic and Martill had identified real differences between these three groups of specimens, they had not provided any rationale that the differences were enough to distinguish them as species, rather than just individual variation, growth changes, or simply due to crushing and distortion during the fossilization process. Bennett pointed in particular to the data used to distinguish ''Aerodactylus'', which was so different from the data for related species, it might be due to an unnatural assemblage of specimens. As a result, Bennett continued to consider ''Diopecephalus'' and ''Aerodactylus'' simply as year-classes of immature ''Pterodactylus antiquus''.

List of species

During its over-200-year history, the various species of ''Pterodactylus'' have gone through a number of changes in classification and thus have acquired a large number of synonyms. Additionally, a number of species assigned to ''Pterodactylus'' are based on poor remains that have proven difficult to assign to one species or another and are therefore considered (). The following list includes names that were used to identify new pterosaur species that now have been reclassified, or until recently thought to be pertaining to ''Pterodactylus'' proper, and names based on other material that has as yet not been assigned to other genera. This list also includes species that are ('naked names'), which are species that were not published formally. Species that are ('forgotten names') are the ones that have been disused, and species that are ('rejected names') are the ones that have been rejected because a more preferable name had been accepted instead.

Cultural significance

''Pterodactylus'' is regarded as one of the most iconic prehistoric creatures, with multiple appearances in books, movies, as well as television series and several videogames. The informal name "pterodactyl" is sometimes used to refer to any kind of animal belonging to the order Pterosauria, though most of the times to ''Pterodactylus'', as it's the most well-known member of the group. The popular aspect of ''Pterodactylus'' consists of an elongated head crest, and potentially large wings. Studies of ''Pterodactylus'' however, conclude that it may even lack a bony cranial crest, though several analysis have proven that ''Pterodactylus'' may in fact have a crest made up of soft tissue instead of bone.

''Pterodactylus'' is the star character of the 2005 horror film '' Pterodactyl'', where it is identified with the informal name "pterodactyl", hence the name of the film. In the film, the "pterodactyls" resemble the aspect of the distantly related genus ''Pteranodon'' due to the elongated bony cranial crest, and their enormous size. One peculiar feature that ''Pterodactylus'' had in the film is the possession of teeth, while this is generally accurate for ''Pterodactylus'', the overall appearance of the creatures in the film is similar to that of ''Pteranodon'', as well as the large size, this makes them resemble some kind of pterosaur identical to ''Pteranodon'', but with the possession of teeth.

Another appearance of ''Pterodactylus''-like creatures is in J. R. R. Tolkien's Middle-earth legendarium. In this novel, the Nazgûl, introduced as the Black Riders, are nine characters who rode flying monsters that looked similarly built to ''Pterodactylus''. Christopher Tolkien, the son of the author, described the flying monsters as "Nazgûl-birds"; his father described the appearance of the steeds as somewhat "pterodactylic", and acknowledged that these were obviously "new mythology".'' Letters of J. R. R. Tolkien'', #211 to Rhona Beare, October 14, 1958'' Letters of J. R. R. Tolkien'', #100 to Christopher Tolkien, May 29, 1945, expressing his "loathing" for the Royal Air Force: "My sentiments are more or less those that Frodo would have had if he discovered some Hobbits learning to ride Nazgûl-birds, 'for the liberation of the Shire'."

See also

* List of pterosaur genera
* Timeline of pterosaur research

References

External links

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Late Jurassic pterosaurs of Europe
Pterodactyloids
Solnhofen fauna
Taxa named by Constantine Samuel Rafinesque
Fossil taxa described in 1809