Ornithocheiromorpha

Early discoveries giganteus, now considered as Lonchodraco giganteus'' The first specimens of ornithocheiromorphs were unearthed at a chalk pit near Burham in Kent, England. In 1846, British paleontologist James Scott Bowerbank named and described the remains found as Pterodactylus giganteus, as it was common at that time to assign any new described pterosaur species to Pterodactylus. In the same chalk pit as P. giganteus, two other pterosaur species were discovered. The first was named in 1851 by Bowerbank as Pterodactylus cuvieri, in honor of the prominent German naturalist and zoologist Georges Cuvier, while the second was described in the same year by British paleontologist Sir Richard Owen as Pterodactylus compressirostris. P. compressirostris later became the type species of a newly created genus called Lonchodectes (meaning "lance biter") in a review by English paleontologist Reginald Walter Hooley in 1914. In 1861, further pterosaur specimens were found in the UK, and were given the new species Pterodactylus simus by Owen. British paleontologist Harry Govier Seeley then created the new genus Ornithocheirus for the new species in the same year, the generic name translating as "bird hand" is due to the notion of the time that pterosaurs were the ancestors of modern birds. In 1870, Seeley reassigned the species Pterodactylus cuvieri as Ornithocheirus cuvieri. In 1874, Richard Owen proposed two new genera, Coloborhynchus, meaning "maimed beak", and Criorhynchus, meaning "ram beak". While Coloborhynchus consisted in a totally new type species, C. clavirostris, as well as two other species reassigned from Ornithocheirus, Criorhynchus consisted entirely of former Ornithocheirus species, including O. simus, which was later reassigned by Owen as Criorhynchus simus. of Pterodactylus cuvieri, now known as Cimoliopterus In 2013, Brazilian paleontologists Taissa Rodrigues & Alexander Kellner made a deeper analysis on the species Pterodactylus cuvieri. In the analysis, they stated that it needed a separate genus, and assigning it to Ornithocheirus was inappropriate, therefore, they created the new genus called Cimoliopterus, with the new resulting combination Cimoliopterus cuvieri. In the same study, Rodrigues & Kellner also reviewed the species Pterodactylus giganteus, and reassigned it to a newly created genus called Lonchodraco, this resulted in a new combination called Lonchodraco giganteus. Seeley also reported another specimen found on the same site. He then considered it another species of Ornithodesmus. In 1901, Seeley named this new species as O. latidens, meaning "wide tooth". Later, Reginald Hooley discussed O. latidens in detail, based on specimens he had found, which led Ornithodesmus to be placed within a new family called Ornithodesmidae. Paleontologist Charles William Andrews however, had expressed doubts as to whether O. latidens belonged in the genus Ornithodesmus, as the vertebrae of the specimen of that genus was based on differed markedly from those of Hooley's specimen. In 1993, the British paleontologists Stafford C. Howse and Andrew C. Milner concluded that the holotype sacrum and only specimen of O. cluniculus didn't belong to a pterosaur, but instead to a maniraptoran theropod dinosaur. They also pointed out that no detailed attempts had been made to compare the sacrum of O. cluniculus with those of pterosaurs, and that O. latidens had in effect been treated as the type species of the genus Ornithodesmus. Howse, Milner, and David Martill in 2001, moved "O." latidens to a new genus called Istiodactylus. They had also named a new family called Istiodactylidae, with Istiodactylus as the only member. Discoveries outside Europe and Ornithocheirus simus'' Other important ornithocheiromorph discoveries include the anhanguerids Tropeognathus and Anhanguera from the Romualdo Formation in Brazil. Tropeognathus was described with its type species, T. mesembrinus in 1987 by German paleontologist Peter Wellnhofer. The generic name is derived from Greek τρόπις, tropis, meaning "keel", and γνάθος, gnathos, meaning "jaw". The specific name is derived from Koine mesembrinos, "of the noontide", simplified as "southern", in reference to the provenance from the Southern Hemisphere. The description then led to an enormous taxonomic confusion. In 1989, Brazilian paleontologist Alexander Kellner considered it an Anhanguera mesembrinus, then a Coloborhynchus mesembrinus by Veldmeijer in 1998, and then a Criorhynchus mesembrinus in 2001 by German paleontologist Michael Fastnacht. T. mesembrinus was then considered a junior synonym of Ornithocheirus simus by British paleontologist David Unwin in 2001, but he then proposed an Ornithocheirus mesembrinus in 2003. '' A discovery in Asia, specifically northwestern China, was reported in 2006. The lake sediments allowed an exceptional preservation of fossils, and therefore paleontologists Qiu Zhanxiang and Wang Banyue started official excavations. Part of the findings consisted of dense concentrations of pterosaur bones, associated with soft tissues and eggs. In 2014, a new species was named and described: Hamipterus tianshanensis. It was named by Wang Xiaolin, Alexander Kellner, Jiang Shunxing, Wang Qiang, Ma Yingxia, Yahefujiang Paidoula, Cheng Xin, Taissa Rodrigues, Meng Xi, Zhang Jialiang, Li Ning, and Zhou Zhonghe. The generic name Hamipterus combines that of the Hami region, with the word pteron, meaning "wing", and the specific name refers to the provenance from the Tian Shan, a mountain range. == Description ==

Size '' compared to a human Ornithocheiromorphs were large pterosaurs, with wingspans normally ranging between . Though its jaws measured only , which was less than 80 percent of the skull's length. Anhanguerids and were typically larger than others of the group and were more successful within the food chain rather than other ornithocheiromorphs, one reason is because of their large size, for example, Tropeognathus mesembrinus, had a normal wingspan of about , and as the maximum estimate. Another species which was impressively large is Coloborhynchus capito, with a total skull length that could have been up to , leading to an estimated wingspan of . However, this species may belong to a different genus called Nicorhynchus. The similar Anhanguera possessed jaws that were tapered in width, but expanded into a broad, spoon-shaped rosette at the tip. The jaws are distinguished from its relatives by several differences in the crest and teeth: unlike its close relatives Coloborhynchus and Ornithocheirus, the crest on the upper jaw of Anhanguera didn't begin at the tip of the snout, therefore, it was set farther back on the skull. Other anhanguerids like Cearadactylus had its first preparations with many serious mistakes: the front of the snout and the lower jaws were confused leading to a reconstruction in which the anterior part of the head was upside down. Some of the teeth were extensively restored and enlarged until the wider front of the jaws showed very large and robust teeth projecting outward. With this arrangement, the maxilla was kinked, and its interlocking teeth suggested that Cearadactylus had a piscivourous diet, allowing the animal to keep hold of slippery fish. Even though most ornithocheiromorphs didn't have a cranial crest like the closely related pteranodontids, there were some exceptions, this included Caulkicephalus and Ludodactylus. Caulkicephalus had a rounded snout, very similar to that of Ornithocheirus and Anhanguera, and therefore it is placed within either Anhangueridae or Ornithocheiridae, depending on the author. Ornithocheiriform teeth were heterodont, and they have sufficient differences that individual teeth can be distinguished between whether they belonged to the rostral, medial, or the posterior portion of the tooth row. The rostral teeth had a subcircular cross-section and their crowns curved more lingually than distally. The medial teeth shared the curvature of the anterior teeth but were more elliptical in cross-section. The posterior teeth were oval in cross-section and curved more distally than lingually. Postcrania '' showing neck and torso vertebrae The vertebral column of ornithocheiromorphs was heavily pneumatized by an extensive system of air sacs, leaving prominent pneumatic foraminae. The neck of ornithocheiromorphs was typically relatively long and robust, being longer than the torso in some derived clades. The neural spines of ornithocheiromorph cervical vertebrae were generally tall and spikelike. Anhanguera, another well-known genus, had a shorter tail, with broad caudal vertebrae that bore a "duplex" cross-section similar to Pteranodon. of Anhanguera santanae, showing its right side The pelvis of ornithocheiromorphs was of moderate size compared to the body as a whole, similar to other ornithocheiroids. The three pelvic bones were often fused, as seen in many species such as Anhanguera santanae, the ilium was long and low, and its front and rear blades projected horizontally beyond the edges of the lower pelvic bones. Despite the structure length, the processes of these rod-like forms indicate that the hindlimb muscles attached to them were limited in strength. The pubic bone was fused with the broad ischium into an ischiopubic blade, resulting in a narrow build. Sometimes, the blades of both sides were fused, closing the pelvis from below and forming the pelvic canal. The front of the pubic bones was also articulated with a unique structure, resulting in a pair of prepubic bones within. This formed a cusp covering the rear belly, and was located between the pelvis and the belly ribs. The hip joint of ornithocheiromorphs was not perforated and allowed considerable mobility to the leg, and suggests that it was vertical, as therefore had a function in breathing, compensating the relative rigidity of the chest cavity. == Classification ==

Several studies show that ornithocheiromorphs were less derived than the toothless pteranodontids such as Pteranodon, and based on the different evolutionary changes, they therefore need to be grouped in a different clade than Pteranodon, though still within Pteranodontoidea. In 2003, David Unwin considered the family Istiodactylidae to group with the toothless Pteranodontidae, within the group Ornithocheiroidea, but Alexander Kellner however, grouped it with the toothed Anhangueridae instead, resulting in a more understandable change of evolution between the two toothed families. Subgroups '', a mimodactylid istiodactyliform Brian Andres and colleagues found the families Istiodactylidae, Ornithocheiridae, and Anhangueridae to form a group in 2014, which he called Lanceodontia. The clade includes most families of ornithocheiromorphs, however they excluded the poorly-known family Lonchodectidae from membership in this clade. In their analysis, they also included the family Boreopteridae within the clade Anhangueria, though placed in a more basal position, while also containing the genus Guidraco. and Andres that these families should not be synonymized based on their original phylogenetical definitions. Subsequent studies in 2019 have found Ornithocheirae to be a more inclusive group containing both Anhangueria (see below) and Targaryendraconia. of Targaryendraco, a targaryendraconian anhanguerian Another constituent clade of Ornithocheiromorpha is Anhangueria. Anhangueria was named by paleontologists Taissa Rodrigues and Alexander Kellner in a review of Ornithocheirus species in 2013, they defined the clade as a branch-based taxon consisting of all pteranodontoids more closely related to Anhanguera blittersdorffi than to Istiodactylus latidens and Cimoliopterus cuvieri. In 2014, paleontologist Brian Andres and colleagues assigned more groups and genera within this clade, this included Guidraco, the subfamily Boreopterinae, and the clade Ornithocheirae, which was further divided into the families Anhangueridae and Ornithocheiridae. In 2019, Alexander Kellner and colleagues described the new ornithocheiromorph Mimodactylus, and used their analysis to name a new clade, Istiodactyliformes. They defined this clade as the most inclusive clade containing Istiodactylus but not Anhanguera. Under their analysis, this new clade included the family Istiodactylidae, Mimodactylidae, and the genus Hongshanopterus. The description of Iberodactylus in Spain also made some paleontologists reclassify the genus Hamipterus in a newly named family called Hamipteridae. The previously recovered basal eupterodactyloid Haopterus was reclassified due to the description of Mimodactylus, and is placed in a new family called Mimodactylidae. However, a more recent analysis using the data in the description of Mimodactylus has found Haopterus as a basal member of the more inclusive group Istiodactyliformes. Many recent analyses have also recovered several ornithocheirids, including Tropeognathus, Coloborhynchus, and Caulkicephalus within the family Anhangueridae, meaning that they were more closely related to Anhanguera than to Ornithocheirus. although some had recovered Camposipterus outside the Anhangueria (within the clade Targaryendraconia), but still within the Ornithocheirae. '', an istiodactylid In their description of Lingyuanopterus in 2022, Xu Yizhi and colleagues recovered the following phylogeny based on the earlier work of Borja Holgado and Rodrigo Pêgas. }} }} }} }} }} }} == Paleobiology ==

Diet and feeding Ornithocheiromorphs were originally regarded as piscivorous creatures, feeding mainly on small and mid-sized fish. An analysis by Witton in 2012 found that the teeth of Istiodactylus were unlike the recurved and enlarged teeth seen in the more derived ornithocheirids such as Ornithocheirus, he instead pointed out that it was more "razor-edged" and better suited for carrion rather than fish. though this conclusion isn't considered entirely accurate. Anhanguerids like Tropeognathus are considered to be fish-eaters, and had longer and sharper teeth compared to the more rounded teeth of Istiodactylus, though this is still sometimes disputed. Another difference that can be seen in more primitive ornithocheiromorphs their eyes being proportionally smaller compared to the assumed predatory and more advanced anhanguerids, this again adds to the fact that the more primitive groups were most likely scavengers, and later got more successful within the food chain, leading the later, more advanced groups to be the dominant fish hunters during the early Late Cretaceous. In teeth microwear analyses, Coloborhynchus appears to have fed on terrestrial vertebrates and invertebrates. Locomotion and flight Ornithocheiromorphs, like other pterosaurs, are considered to have been skilled fliers as well as swift at moving on the ground. Footprints from several species show that most pterosaurs did not sprawl their limbs to a large degree, as in modern reptiles, but rather held the limbs relatively erect when walking, like dinosaurs. While footprints are yet to be known, it is likely that ornithocheiromorphs also walked erect. Compared to other earlier pterosaurs such as rhamphorhynchids, ornithocheiromorphs had unusually uneven limb proportions, with the forelimbs resulting in a much longer scale compared to the hind limbs. Their close relatives, the pteranodontids, were also found with similar features, though they more likely flew like modern-day albatrosses rather than anything else. Paleontologists also suggest that they most likely spend long stretches of time sea fishing, traveling very long distances without flapping while at the same time flying close the surface of the water with exploited wind speed, and without the necessity of thermals. This would likely have required them to use unique modes of locomotion compared to other pterosaurs, this can already be seen in earlier evolutions such as Istiodactylus and Nurhachius, with powerful musculature attachments and well-developed pectoral and upper arm bones. It is also possible that ornithocheiromorphs ran (but not walked) bipedally, or that they used a hopping gait. == Paleoecology ==

of the Araripe Basin, with the extent of the Santana Group shown in dark blue Even though the ornithocheiromorphs were discovered worldwide, most of them were concentrated in specific places. One of which is the fossil site called Romualdo Formation, which contains an impressive amount of pterosaur fossils. It is a diverse Lagerstätte in the larger geologic group called the Santana Group (sometimes called the Santana Formation), which is located in the Araripe Basin of northeastern Brazil, and dates back around 111 and 108 million years ago, during the Albian stage of the Early Cretaceous. The formation includes many species of Anhanguera, as well as the tapejarid Tapejara. '' with a possible anhanguerid in its jaws Some other creatures from the formation include the theropods Irritator, Mirischia and Santanaraptor, and the crocodylomorph Araripesuchus. The formation also includes several turtle remains, with some specimens referring to Santanachelys, Cearachelys and Araripemys. A few fish remains were also found within the Romualdo Formation, some of which were referred to Brannerion, Rhinobatos, Rhacolepis, Tharrhias and Tribodus. The Santana Group also consists of another Lagerstätte called the Crato Formation, which is not as diverse as the Romualdo Formation, but its fossil remains are still considered important. This fossil site underlies the Romualdo Formation, and dates back around 115 and 113 million years ago during the Aptian stage, meaning that its fossil content is of older age. Similarly, the Crato Formation also contained several species of pterosaurs, including the basal lanceodontians Ludodactylus Cladocyclus, Dastilbe and Lepidotes. These fish genera were suggested to be prey for the pterosaurs that lived in the formation, but fossil remains are limited, so the subject is still controversial. The formation is also known for several theropods, including the spinosaurid Baryonyx, the tyrannosauroid Eotyrannus, the dromaeosaurid Ornithodesmus, the compsognathid Aristosuchus as well as the allosauroid Neovenator. Different types of herbivorous dinosaurs like Iguanodon, Polacanthus, Ornithopsis, Mantellisaurus and Hypsilophodon were also found within the fossil site. Some other animals from the formation include the neosuchian Bernissartia, sea turtles such as Helochelydra and Brodiechelys, the cartilaginous fish Hybodus, ray-finned fishes such as Belonostomus, Caturus, Lepidotes and Scheenstia, as well as the mammals Eobaatar, Loxaulax and Yaverlestes. on a diagram showing the known material, and based on the related Tropeognathus mesembrinus'' A few fossils reported from the Toolebuc Formation and Winton Formation are believed to be from some of the last ornithocheiromorphs, due to the age of the fossil remains, which dated back to the Albian and Cenomanian stages of the Cretaceous, and some are even believed to belong to the Turonian stage. The Toolebuc Formation includes several remains of ornithocheiromorphs which are now referred to the genera Aussiedraco and Mythunga. The formation also includes several herbivorous dinosaurs such as the ornithopod Muttaburrasaurus and the ankylosaur Kunbarrasaurus. Fossil remains of marine animals were also uncovered within the fossil site, and some specimens of which belong to the ichthyosaur Platypterygius, the pliosaurid Kronosaurus and the elasmosaurid Eromangasaurus. Turtle remains from turtles that were proposed to be prey for pterosaurs were also found within the Toolebuc Formation, this included the genera Bouliachelys, Cratochelone and Notochelone. and crocodylomorphs like Isisfordia. The formation's only pterosaur is the derived genus Ferrodraco, which is also considered as one of the last ornithocheiromorphs, and a close relative of Mythunga. == See also ==