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 sternum, which is where its flight muscles attached. Its skull was long and its eye sockets were the largest opening therein. Large curved fangs that "intermeshed" when the jaws closed featured prominently at the front of the snout while smaller, straighter teeth lined the back.
Having two or more morphs of teeth, a condition called heterodonty, is rare in modern reptiles but more common in basal ("primitive") pterosaurs. Its heterodont dentition and direct dietary evidence based on gut contents suggest that Dorygnathus is a piscivore (fish-eater). The fifth digit on the hindlimbs of Dorygnathus was unusually long and oriented to the side. Its function is not certain, but the toe may have supported a membrane like those supported by its wing-fingers and pteroids. Dorygnathus was according to David Unwin related to the Late Jurassic pterosaur Rhamphorhynchus and was a contemporary of Campylognathoides in Holzmaden and Ohmden.
Discovery
The first remains of Dorygnathus, isolated bones and jaw fragments from the Schwarzjura, the Posidonia Shale dating from the Toarcian, were discovered near Banz, Bavaria and in 1830 described by Carl Theodori as Ornithocephalus banthensis; the specific name referring to Banz.Theodori, C. (1830). "Knochen vom Pterodactylus aus der Liasformation von Banz", Frorieps Notizen für Natur- und Heilkunde, n. 632, 101pp In 1831 however, Theodori reassigned the species to the genus Pterodactylus, therefore creating P. banthensis.Theodori, C. (1831). "Ueber die Knochen vom Genus Pterodactylus aus der Liasformation der Gegend von Banz", Okens Isis, 3: 276–281 The holotype, a lower jaw, is specimen PSB 757. The fossils were studied by Christian Erich Hermann von Meyer in 1831Meyer, H. von (1831). "Über Macrospondylus und Pterodactylus", Nova Acta Academia Caesarae Leopold-Carolina Germania Naturali Curiae, 15: 198–200 and again by Theodori in 1852 when he referred them to the genus Rhamphorhynchus instead of Pterodactylus.Theodori, C. (1852). "Ueber die Pterodactylus-Knochen im Lias von Banz", Berichte des Naturforschenden Vereins Bamberg, 1: 17–44 In this period a close affinity was assumed with a pterosaur known from Britain, later named Dimorphodon. Some fossils were sent to a professor of paleontology in Munich named Johann Andreas Wagner. It was he who, having studied new finds by Albert Oppel in 1856 and 1858,Oppel, A. (1856). "Die Juraformation", Jahreshefte des Vereins für Vaterländische Naturkunde in Württemberg, 12Oppel, A. (1858). "Die Geognostische Verbreitung der Pterodactylen", Jahreshefte der Vereins der vaterländische Naturkunde in Württemberg, 1858, Vorträge 8, 55 pp after Richard Owen had named Dimorphodon concluded that the German type was clearly different and that therefore a new genus of pterosaur should be erected, which he formally named Dorygnathus in 1860, from Greek dory, "spear" and gnathos, "jaw".Wagner, A. (1860). "Bemerkungen über die Arten von Fischen und Sauriern, Welche im untern wie im oberen Lias zugleich vorkommen sollen", Sitzungsberichte der königlichen Bayerischen Akademie der Wissenschaften, mat.- physikalische Classe, p. 36-52 Much more complete remains have been found since in other German locales and especially in Württemberg, including Holzmaden, Ohmden, and Zell."Dorygnathus." In: Cranfield, Ingrid (ed.). The Illustrated Directory of Dinosaurs and Other Prehistoric Creatures. London: Salamander Books, Ltd. Pp. 292-295. One specimen, SMNS 81840, has in 1978 been dug up in Nancy, France.Dominique Delsate & Rupert Wild. (2000). "Première Découverte d'un Reptile volant determinable (Pterosauria, Dorygnathus cf banthensis) du Toracien inférieur (Jurassique inférieur) de Nancy (Lorraine, France)", Bulletin de l'Académie et de la Société lorraines des sciences, 2000, 39: 1-4 Dorygnathus fossils were often found in the spoil heaps where unusable rock was dumped from slate quarries worked by local farmers.Keller, Thomas (1985). "Quarrying and Fossil Collecting in the Posidonienschiefer (Upper Liassic) around Holzmaden, Germany", Geological Curator, 4(4): 193-198 Most fossils were found in two major waves, one during the 1920s, the other during the 1980s. Since then the rate of discovery has slowed considerably because the demand for slate has strongly diminished and many small quarries have closed. At present over fifty specimens have been collected, many of them are preserved in the collection of the State Museum of Natural History Stuttgart, as by law paleontological finds in Baden-Württemberg are property of this Bundesland. Due to the excellent preserval of the later found fossils, Dorygnathus has generated much interest by pterosaur researchers, important studies having been dedicated to the species by Felix Plieninger,Plieninger, F. (1907). "Die Pterosaurier der Juraformation Schwabens", Palaeontographica, 53: 209–313 Gustav von Arthaber,Arthaber, G.E. von (1919). "Studien über Flugsaurier auf Grund der Bearbeitung des Wiener Exemplares von Dorygnathus banthensis Theod. sp.", Denkschriften der Akademie der Wissenschaften Wien, Mathematisch-naturwissenschaftliche Klasse, 97: 391–464 and more recently Kevin Padian.Padian, K. & Wild, R. (1992). "Studies of Liassic Pterosauria, I. The holotype and referred specimens of the Liassic Pterosaur Dorygnathus banthensis (Theodori) in the Petrefaktensammlung Banz, Northern Bavaria", Palaeontographica Abteilung A, 225: 55-79
In 1971 Rupert Wild described and named a second species: Dorygnathus mistelgauensis,Wild, R. (1971). "Dorygnathus mistelgauensis n. sp., ein neuer Flugsaurier aus dem Lias Epsilon von Mistelgau (Frankischer Jura)" — Geol. Blatter NO-Bayern, 21(4): 178-195 based on a specimen collected in a brick pit near the railway station of Mistelgau, to which the specific name refers, by teacher H. Herppich, who donated it to the private collection of Günther Eicken, a local amateur paleontologist at Bayreuth, where it still resides. As a result, the exemplar has no official inventory number. The fossil comprises a shoulder-blade with wing, a partial leg, a rib and a caudal vertebra. Wild justified the creation of a new species name by referring to the great size, with an about 50% larger wingspan than with a typical specimen; the short lower leg and the long wing.
Padian in 2008 pointed out that D. banthensis specimen MBR 1977.21, the largest then known, has with a wingspan of 169 centimetres an even larger size; that wing and lower leg proportions are rather variable in D. banthensis and that the geological age is comparable. He concluded that D. mistelgauensis is a subjective junior synonym of D. banthensis.
Description
Dorygnathus in general has the build of a basal, i.e. non-pterodactyloid pterosaur: a short neck, a long tail and short metacarpals — although for a basal pterosaur the neck and metacarpals of Dorygnathus are again relatively long. The skull is elongated and pointed. The largest known cranium, that of specimen MBR 1920.16 prepared by Bernard Hauff in 1915 and eventually acquired by the Natural History Museum of Berlin, has a length of sixteen centimetres. In the skull the eye socket forms the largest opening, larger than the fenestra antorbitalis that is clearly separated from the slit-like bony naris. No bony crest is visible on the rather straight top of the skull or snout. The lower jaws are thin at the back but deeper toward the front where they fuse into the symphysis ending in a toothless point after which the genus has been named. In MBR 1920.16, the mandibula as a whole has a length of 147 millimetres.Kevin Padian (2008). The Early Jurassic Pterosaur Dorygnathus Banthensis(Theodori, 1830). Special Papers in Palaeontology No. 80, The Palaeontological Association, London
In the lower jaws the first three pairs of teeth are very long, sharp and pointing outwards and forwards. They contrast with a row of eight or more upright-standing much smaller teeth that gradually diminish in size towards the back of the lower jaw. No such extreme contrast exists in the upper jaws, but the four teeth in the premaxilla are longer than the seven in the maxilla that again become smaller posteriorly. The total number of teeth is thus at least 44. The long upper and lower front teeth interlaced when the beak was closed; due to their extreme length they then projected considerably beyond the upper and lower margins of the head.
According to Padian, eight cervical, fourteen dorsal, three or four sacral and twenty-seven or twenty-eight caudal vertebrae are present. The exceptional fourth sacral is the first of the normal caudal series. The number of caudals is not certain because their limits are obscured by long thread-like extensions, stiffening the tail. The cervical vertebrae are rather long and strongly built, their upper surface having a roughly square cross-section. They carry double-headed thin cervical ribs. The dorsal vertebrae are more rounded with flat spines; the first three or four carry ribs that contact the sternal ribs; the more posterior ribs contact the gastralia. The first five or six, rather short, caudal vertebrae form a flexible tail base. To the back the caudals grow longer and are immobilised by their intertwining extensions with a length of up to five vertebrae which together surround the caudals with a bony network, allowing the tail to function as a rudder. The breastbone is triangular and relatively small; Padian has suggested it may have been extended at its back with a cartilaginous tissue. It is connected to the coracoid which in older individuals is fused to the longer scapula forming a saddle-shaped shoulder joint. The humerus has a triangular deltopectoral crest and is pneumatised. The lower arm is 60% longer than the upper arm. From the five carpal bones in the wrist a short but robust pteroid points towards the neck, in the living animal a support for a flight membrane, the propatagium. The first three metacarpals are connected to three small fingers, equipped with short but strongly curved claws; the fourth to the wing finger, in which the second or third phalanx is the longest; the first or fourth the shortest. The wing finger supports the main flight membrane.
In the pelvis, the ilium, ischium and pubis are fused. The ilium is elongated with a length of six vertebrae. The lower leg, in which the lower two thirds of the tibia and fibula of adult specimens are fused, is a third shorter than the thighbone, the head of which makes an angle of 45° with its shaft. The proximal tarsals are never fused in a separate astragalocalcaneum; a tibiotarsus is formed. The third metatarsal is the longest; the fifth is connected to a toe of which the second phalanx shows a 45° bend and has a blunt and broad end; it perhaps supported a membrane between the legs, a cruropatagium.
In some specimens, soft parts have been preserved but these are rare and limited, providing little information. It is unknown whether the tail featured a vane on its end, as with Rhamphorhynchus. However, Ferdinand Broili reported the presence of hairs in specimen BSP 1938 I 49,Broili, F. (1939) "Ein Dorygnathus mit Hautresten", Sitzungs-Berichte der Bayerischen Akademie der Wissenschaften, Mathematisch-naturwissenschaftliche Abteilung, 1939: 129–132 an indication that Dorygnathus also had pycnofibers or feathers and an elevated metabolism, as is presently assumed for all pterosaurs.
Phylogeny