''Dearc'' ( ) is a genus of large-bodied

rhamphorhynchine Rhamphorhynchidae is a group of early pterosaurs named after '' Rhamphorhynchus'', that lived in the Late Jurassic. The family Rhamphorhynchidae was named in 1870 by Harry Govier Seeley.Seeley, H.G. (1870). "The Orithosauria: An Elementary Stud ...

pterosaur from the Middle Jurassic Lealt Shale Formation of

Scotland Scotland (, ) is a country that is part of the United Kingdom. Covering the northern third of the island of Great Britain, mainland Scotland has a border with England to the southeast and is otherwise surrounded by the Atlantic Ocean to the ...

. The holotype, a juvenile or subadult that was still actively growing, has an estimated wingspan of 2.5 to 3 meters, making it the largest flying animal of its time. This pushes the origin of large pterosaurs back significantly, as it was previously assumed that pterosaurs did not reach greater body sizes until the short-tailed pterodactyloid lineages of the

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...

. The genus contains a single species, ''Dearc sgiathanach'' ( ).

Discovery and naming

The

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

of ''Dearc'', NMS G.2021.6.1-4, was found in 2017 by Amelia Penny in the

Lealt Shale Formation The Lealt Shale Formation is a Middle Jurassic geologic formation in Scotland. Fossil ornithopod , theropod and stegosaur tracks, a theropod dinosaur tooth and the pterosaur ''Dearc'' have been reported from the formation.Weishampel, et al. (20 ...

and consists of a three-dimensionally preserved skeleton preserved in articulation in a slab of

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

(separated into four pieces for preparation). The specimen preserves most of the body with the exception of the end of the tail, most of the hindlimbs, parts of the wing and the very tip of the beak. The specimen was found on the east coast of the peninsula of

Trotternish Trotternish or Tròndairnis (Scottish Gaelic) is the northernmost peninsula of the Isle of Skye, in Scotland. Its most northerly point, Rubha Hùinis, is the most northerly point of Skye. One of the peninsula's better-known features is the Trot ...

, part of the

Isle of Skye The Isle of Skye, or simply Skye (; gd, An t-Eilean Sgitheanach or ; sco, Isle o Skye), is the largest and northernmost of the major islands in the Inner Hebrides of Scotland. The island's peninsulas radiate from a mountainous hub dominated ...

in north-west

, and the rock slab removed to the

University of Edinburgh The University of Edinburgh ( sco, University o Edinburgh, gd, Oilthigh Dhùn Èideann; abbreviated as ''Edin.'' in post-nominals) is a public research university based in Edinburgh, Scotland. Granted a royal charter by King James VI in 15 ...

. The fossil was prepared by Nigel Larkin. It is to be displayed by

National Museums Scotland National Museums Scotland (NMS; gd, Taighean-tasgaidh Nàiseanta na h-Alba) is an executive non-departmental public body of the Scottish Government. It runs the national museums of Scotland. NMS is one of the country's National Collections, ...

. In 2022, the

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

''Dearc sgiathanach'' was named and described by Natalia Jagielska, Michael O’Sullivan, Gregory F. Funston, Ian B. Butler, Thomas J. Challands, Neil D.L. Clark, Nicholas C. Fraser, Amelia Penny, Dugald A. Ross, Mark Wilkinson and Stephen Louis Brusatte. The name is derived from the

Scottish Gaelic Scottish Gaelic ( gd, Gàidhlig ), also known as Scots Gaelic and Gaelic, is a Goidelic language (in the Celtic branch of the Indo-European language family) native to the Gaels of Scotland. As a Goidelic language, Scottish Gaelic, as well as ...

language and has a double meaning. It can be simultaneously translated as "winged reptile" and "reptile from Skye", as ''dearc'' means "reptile" and ''sgiathanach'' (from ''sgiathan'' "small wing") means "winged", an element that also appears in the Gaelic name of the

(), often interpreted as meaning "The Winged Island".

Description

Size

The wingspan could not be directly measured for ''Dearc'' as several

phalanges The phalanges (singular: ''phalanx'' ) are digital bones in the hands and feet of most vertebrates. In primates, the thumbs and big toes have two phalanges while the other digits have three phalanges. The phalanges are classed as long bones. ...

of the wingfinger were missing, in particular the very tip and a central portion of the wing. However, an estimate could be made based on comparison with better sampled taxa, in this case ''Rhamphorhynchus'' and '' Dorygnathus''. Using the proportions of ''Rhamphorhynchus'', an estimated wingspan between 2.2 meters (based on skull length) and 3.8 meters (based on humerus length) was recovered. Estimates based on the humerus length of ''Dorygnathus'' give an estimated wingspan of 1.9 meters. These results already make ''Dearc'' one of the largest known Jurassic pterosaurs, larger than the largest ''Dorygnathus'' (1.69 meters wingspan) and smaller among non-pterodactyloids only than a large rhamphorhynchid specimen from Ettling in

Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...

, consisting of two possible neck vertebrae, which may belong to the genus ''Rhamphorhynchus''. The larger interpretation is favored by the authors for a series of reasons including the well established ontogenetic series of ''Rhamphorhynchus'',

phylogenetic proximity In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

. ''Dearc'' possesses several features typical of fully grown adults in the related '' Rhamphorhynchus'', including the large recurved teeth of the

premaxilla The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammal has b ...

, the well developed crest of the

humerus The humerus (; ) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius and ulna, and consists of three sections. The humeral upper extremity consists of a roun ...

, fusion between the

scapula The scapula (plural scapulae or scapulas), also known as the shoulder blade, is the bone that connects the humerus (upper arm bone) with the clavicle (collar bone). Like their connected bones, the scapulae are paired, with each scapula on eithe ...

- coracoid, smooth bone texture and other features. However, at the same time other areas of the fossil show signs of immaturity, including unfused bones of the skull and unfused

sacral vertebrae The sacrum (plural: ''sacra'' or ''sacrums''), in human anatomy, is a large, triangular bone at the base of the spine that forms by the fusing of the sacral vertebrae (S1S5) between ages 18 and 30. The sacrum situates at the upper, back part ...

Histology Histology, also known as microscopic anatomy or microanatomy, is the branch of biology which studies the microscopic anatomy of biological tissues. Histology is the microscopic counterpart to gross anatomy, which looks at larger structures vis ...

supports the later interpretation, indicating that, while at least two years old at its time of death, the animal was still actively growing. The wing bone shows two prominent lines of growth that allow this interpretation and further suggest that it died shortly after emerging from a hiatus in growth. The fact that the holotype of ''Dearc'' was still growing makes a wingspan of up to three meters quite possible.

Skeletal anatomy

Generally, ''Dearc'' shows the typical bodyplan of non-

monofenestrata Monofenestrata is an unranked group of pterosaurs that includes the family Wukongopteridae and the suborder Pterodactyloidea. The clade Monofenestrata was in 2009/2010 defined as the group consisting of ''Pterodactylus'' and all species sharing ...

n pterosaurs. The neck was short and the tail elongated, supported by interlocking zygapophyses of the caudal vertebrae. The mandibular symphysis is elongated and the

metacarpus In human anatomy, the metacarpal bones or metacarpus form the intermediate part of the skeletal hand located between the phalanges of the fingers and the carpal bones of the wrist, which forms the connection to the forearm. The metacarpal bones ...

short. There are however some features shared with pterodactyloids such as a skull longer than the dorsal and sacral vertebrae combined and the shape of the

quadrate Quadrate may refer to: * Quadrate bone * Quadrate (heraldry) * Quadrate lobe of liver * Quadrate tubercle The quadrate tubercle is a small tubercle found upon the upper part of the femur. It serves as a point of insertion of the quadratus femori ...

. Furthermore, although proportionally short compared to pterodactyloids, the

cervical vertebrae In tetrapods, cervical vertebrae (singular: vertebra) are the vertebrae of the neck, immediately below the skull. Truncal vertebrae (divided into thoracic and lumbar vertebrae in mammals) lie caudal (toward the tail) of cervical vertebrae. In ...

are notably elongated compared to other non-monofenestratans, resembling those of the more derived ''

Wukongopterus ''Wukongopterus'' is a genus of basal pterosaur, found in Liaoning, China, from the Daohugou Beds, of the Middle or Late Jurassic. It was unusual for having both an elongate neck and a long tail. The genus was described and named in 2009 by ...

''. The dentition shows two distinct types of teeth: elongated fangs close to the tip of the snout and more conical peg-like teeth further back. The describing authors indicated several distinguishing traits. Four are autapomorphies, unique derived characters. In the palate, the vomers contain three tubes, forming a trident. The contribution of the upper jaw bone, the maxilla, to the palate, in front of the

choana The choanae (singular choana), posterior nasal apertures or internal nostrils are two openings found at the back of the nasal passage between the nasal cavity and the throat in tetrapods, including humans and other mammals (as well as crocodilia ...

, the inner nostril, has a depression. The brain has enlarged optic lobes that are expanded lengthwise. In the foot the fourth metatarsal is more robust than the first, second and third metatarsal, about 2.5 times as thick. Additionally, there are two traits that in themselves are not unique but the combination of which is unique. The

infratemporal fenestra An infratemporal fenestra, also called the lateral temporal fenestra or simply temporal fenestra, is an opening in the skull behind the orbit in some animals. It is ventrally bordered by a zygomatic arch. An opening in front of the eye sockets, ...

is pear-shaped, with the narrow part on top. In the palate, the ectopterygoid bone has an upwards projecting process, running through the choana and perpendicularly contacting the vomer.

Phylogeny

The phylogenetic analysis conducted for ''Dearc'' included characters from several independent publications as well as entirely new ones, while also excluding those that are only known from very young animals or known to vary greatly with age. The resulting tree recovered ''Dearc'' to lie within the Rhamphorhynchidae, specifically in a clade alongside '' Angustinaripterus'' and '' Sericipterus'', the

Angustinaripterini Rhamphorhynchidae is a group of early pterosaurs named after '' Rhamphorhynchus'', that lived in the Late Jurassic. The family Rhamphorhynchidae was named in 1870 by Harry Govier Seeley.Seeley, H.G. (1870). "The Orithosauria: An Elementary Stud ...

References

{{Taxonbar, from1=Q110983876, from2=Q110986200 Jurassic pterosaurs of Europe Jurassic reptiles of Europe Rhamphorhynchids Fossil taxa described in 2022 Pterosaurs Isle of Skye Fossils of Scotland Jurassic Scotland