''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 Study o ...
pterosaur from the Middle Jurassic
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. (2 ...
of
Scotland
Scotland is a Countries of the United Kingdom, country that is part of the United Kingdom. It contains nearly one-third of the United Kingdom's land area, consisting of the northern part of the island of Great Britain and more than 790 adjac ...
. 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
Pterodactyloidea ( ; derived from the Greek words ''πτερόν'' (''pterón'', for usual ''ptéryx'') "wing", and ''δάκτυλος'' (''dáktylos'') "finger") is one of the two traditional suborders of pterosaurs ("wing lizards"), and contai ...
lineages of the
Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...
. The genus contains a single species, ''Dearc sgiathanach'' ( ).
Discovery and naming
The
holotype
A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...
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. (2 ...
and consists of a three-dimensionally preserved skeleton preserved in articulation in a slab of
limestone
Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...
(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 () is the northernmost peninsula of the Isle of Skye in Scotland, spanning in length from Portree to Rubha Hunish. The Trotternish escarpment runs almost the full length of the peninsula, some ,Ordnance Survey ''Landranger'' 1:50000 ...
, part of the
Isle of Skye
The Isle of Skye, or simply 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 by the Cuillin, the rocky slopes of which provide some of ...
in north-west
Scotland
Scotland is a Countries of the United Kingdom, country that is part of the United Kingdom. It contains nearly one-third of the United Kingdom's land area, consisting of the northern part of the island of Great Britain and more than 790 adjac ...
, and the rock slab removed to the
University of Edinburgh
The University of Edinburgh (, ; abbreviated as ''Edin.'' in Post-nominal letters, post-nominals) is a Public university, public research university based in Edinburgh, Scotland. Founded by the City of Edinburgh Council, town council under th ...
.
The fossil was prepared by Nigel Larkin. It is to be displayed by
National Museums Scotland
National Museums Scotland (NMS; ) 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, and holds internationally important collec ...
.
In 2022, the
type species
In International_Code_of_Zoological_Nomenclature, 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 spe ...
''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 (, ; Endonym and exonym, endonym: ), also known as Scots Gaelic or simply Gaelic, is a Celtic language native to the Gaels of Scotland. As a member of the Goidelic language, Goidelic branch of Celtic, Scottish Gaelic, alongs ...
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
Isle of Skye
The Isle of Skye, or simply 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 by the Cuillin, the rocky slopes of which provide some of ...
(), often interpreted as meaning "The Winged Island".
Description
Size

The wingspan could not be directly measured for ''Dearc'' as several
phalanges
The phalanges (: phalanx ) are digit (anatomy), digital bones in the hands and foot, feet of most vertebrates. In primates, the Thumb, thumbs and Hallux, big toes have two phalanges while the other Digit (anatomy), digits have three phalanges. ...
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
''Dorygnathus'' ("spear jaw") was a genus of rhamphorhynchid pterosaur that lived in Europe during the Early Jurassic period, when shallow seas flooded much of the continent. It had a short wingspan around , and a relatively small triangular ster ...
''. 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 lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...
, 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 () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical data ...
.[
''Dearc'' possesses several features typical of fully grown adults in the related '']Rhamphorhynchus
''Rhamphorhynchus'' (, from Ancient Greek ''rhamphos'' meaning "beak" and ''rhynchus'' meaning "snout") is a genus of long-tailed pterosaurs in the Jurassic period. Less specialized than contemporary, short-tailed pterodactyloid pterosaurs such ...
'', 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 mammals h ...
, the well developed crest of the humerus
The humerus (; : humeri) 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 (bone), radius and ulna, and consists of three sections. The humeral upper extrem ...
, fusion between the scapula
The scapula (: 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 either side ...
-coracoid
A coracoid is a paired bone which is part of the shoulder assembly in all vertebrates except therian mammals (marsupials and placentals). In therian mammals (including humans), a coracoid process is present as part of the scapula, but this is n ...
, 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 (: sacra or sacrums), in human anatomy, is a 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 of the pelvic cavity, ...
. Histology
Histology,
also known as microscopic anatomy or microanatomy, is the branch of biology that studies the microscopic anatomy of biological tissue (biology), tissues. Histology is the microscopic counterpart to gross anatomy, which looks at large ...
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 a clade of pterosaurs. It includes the pterosaurs in which the nasal and antorbital fenestra (openings/holes) in the skull are merged into a single fenestra. The clade includes the pterodactyloids and their close relatives.
C ...
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, also known as the "palm bones", are the appendicular skeleton, appendicular bones that form the intermediate part of the hand between the phalanges (fingers) and the carpal bones (wrist, wris ...
short. There are however some features shared with pterodactyloids
Pterodactyloidea (International Phonetic Alphabet, ; derived from the Ancient Greek, Greek words ''πτερόν'' (''pterón'', for usual ''ptéryx'') "wing", and ''δάκτυλος'' (''dáktylos'') "finger") is one of the two traditional subor ...
such as a skull longer than the dorsal and sacral vertebrae combined and the shape of the quadrate. Furthermore, although proportionally short compared to pterodactyloids, the cervical vertebrae
In tetrapods, cervical vertebrae (: 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 saurop ...
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 Tiaojishan Formation, of the Middle or Late Jurassic. It was unusual for having both an elongate neck and a long tail.
Discovery and naming
The genus was desc ...
''. 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
In phylogenetics, an autapomorphy is a distinctive feature, known as a derived trait, that is unique to a given taxon. That is, it is found only in one taxon, but not found in any others or outgroup taxa, not even those most closely related to ...
, 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 (: choana), posterior nasal apertures or internal nostrils are two openings found at the back of the nasal passage between the nasal cavity and the pharynx, in humans and other mammals (as well as crocodilians and most skinks). They ...
, 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
Temporal fenestrae are openings in the temporal region of the skull of some amniotes, behind the orbit (eye socket). These openings have historically been used to track the evolution and affinities of reptiles. Temporal fenestrae are commonly (al ...
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.[
''Dearc'' possesses large, highly curved manual unguals with well-developed sesamoids and flexor tendons. This would suggest the claws would be retractable to some extent, allowing ''Dearc'' to elevate the tips of its claws above substrate when walking to maintain their function. The morphology of the claws suggests a role in ]scansorial
Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally (scansorial), but others are exclusively arboreal. The habi ...
or arboreal
Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally (scansorial), but others are exclusively arboreal. The hab ...
locomotion and perhaps supplement in predation
Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common List of feeding behaviours, feeding behaviours that includes parasitism and micropredation ...
, though more extensive analyses of the ungual morphologies of the taxon and other non-monofenestran pterosaurs with extant taxa is required.
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
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 Study ...
, specifically in a clade alongside ''Angustinaripterus
''Angustinaripterus'' was a basal pterosaur, belonging to the breviquartossan family Rhamphorhynchidae (more specifically within the subfamily Rhamphorhynchinae) and discovered at Dashanpu near Zigong in the Sichuan province of China.
Discovery ...
'' and '' Sericipterus'', the Angustinaripterini.[
]
References
{{Taxonbar, from1=Q110983876, from2=Q110986200
Jurassic pterosaurs of Europe
Rhamphorhynchidae
Fossil taxa described in 2022
Isle of Skye
Fossils of Scotland
Jurassic Scotland
Bathonian genera
Middle Jurassic reptiles of Europe