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Pterodactylus


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Pterodactylus (Latin scientific Pterosauria) was a Pterosaur from late Jurassic Europe. A contemporary of Rhamphorhynchus, it was one of the first pterodactyloid pterosaurs in the world, and its' name is often confused with Pteranodon. Pterodactylus lived in the Late Jurassic Period about 150 to 145 million years ago.

Pterodactylus was a small reptile, hardly larger than a modern pigeon or crow.

It still had teeth, but of a more uniform and smaller size than Rhamphorhynchus. Pterodactylus may have had a crest of skin on its head.

Pterodactylus had almost no tail, unlike Rhamphorhynchus, and it held its neck at an angle, not straightforward, as Rhamphorhynchus did. It was more adapted to moving on land as well, though at its smaller size, it was still vulnerable to dinosaurs and other terrestrial inhabitants.

Both Pterodactylus and Rhamphorhynchus are found in Solnhofen deposits of modern Germany, alongside the ancient bird Archaeopteryx and the small dinosaur Compsognathus.

Discovery and history

Pterodactylus is a case study in how confusing it can be to classify 150-million-year-old animals. The first specimen of this pterosaur was discovered way back in 1784, in Germany's Solnhofen fossil beds, decades before before naturalists had any conception of the theory of evolution (which wouldn't be scientifically formulated, by Charles Darwin, until about 70 years later) or, indeed, any grasp of the possibility that animals could go extinct. Fortunately, in retrospect, Pterodactylus was named by one of the first academics to grapple with these issues, the Frenchman Georges Cuvier.

Description

Pterodactylus is known from over 30 fossil specimens, and though most belong to juveniles, many preserve complete skeletons.

Paleobiology

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 15 to 45 millimeters (0.59 to 1.77 in) in length. The second year class is characterized by skulls of around 55 to 95 millimeters (2.2 to 3.7 in) 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.

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.

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.

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.

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 and Eichstaettisaurus. 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.

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".

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