Eudimorphodon

Eudimorphodon was a pterosaur that was discovered in 1973 by Mario Pandolfi in the town of Cene, Italy and described the same year by Rocco Zambelli. The nearly complete skeleton was retrieved from shale deposited during the Late Triassic (mid to late Norian stage),[1] making Eudimorphodon one of the oldest pterosaurs known.[2] It had a wingspan of about 100 centimetres (3.3 ft) and at the end of its long bony tail may have been a diamond-shaped flap like in the later Rhamphorhynchus. If so, the flap may have helped it steer while maneuvering in the air.[3] Eudimorphodon is known from several skeletons, including juvenile specimens.

Eudimorphodon
Temporal range: Late Triassic, 210–203 Ma
Eudimorphodon
MCSNB 2888 in Bergamo
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Order: Pterosauria
Family: Eudimorphodontidae
Subfamily: Eudimorphodontinae
Genus: Eudimorphodon
Zambelli, 1973
Species:
E. ranzii
Binomial name
Eudimorphodon ranzii
Zambelli, 1973

Description

Eudimorphodon NT small
Restoration

Eudimorphodon was a small pterosaur, being 1 metre (3.3 ft) in length, and weighing no more than 10 kilograms (22 lb). Its fourth finger had a very large size, and attached to the membrane making up the wing.[4]

Eudimorphodon showed a strong differentiation of the teeth, hence its name, which is derived from ancient Greek for "true dimorphic tooth". It also possessed a large number of these teeth, a total of 110 of them densely packed into a jaw only six centimeters long. The front of the jaw was filled with fangs, per side four in the upper jaw, two in the lower jaw, that rather abruptly gave way to a line of smaller multipointed teeth, 25 in the upper jaw, 26 in the lower jaw, most of which had five cusps[2]

The morphology of the teeth are suggestive of a piscivorous diet, which has been confirmed by preserved stomach contents containing the remains of fish of the genus Parapholidophorus. Eudimorphodon had slightly differing dentition with fewer teeth and may have had a more insectivorous diet.[2] The top and bottom teeth of Eudimorphodon came into direct contact with each other when the jaws were closed, especially at the back of the jaw. This degree of dental occlusion is the strongest known among pterosaurs. The teeth were multi-cusped, and tooth wear shows that Eudimorphodon was able to crush or chew its food to some degree. Wear along the sides of these teeth suggests that Eudimorphodon also fed on hard-shelled invertebrates.[5] The teeth distinguish Eudimorphodon, because almost all other pterosaurs either had simple teeth, or lacked them altogether. Benson et al. (2012) noticed that the teeth would have been perfect for grabbing and crushing fish.[4]

Phylogeny and classification

Despite its great age, Eudimorphodon has few primitive characteristics[2] making the taxon of little use in attempting to ascertain where pterosaurs fit in the reptile family tree. Basal traits though, are the retention of pterygoid teeth and the flexibility of the tail, which lacks the very long stiffening vertebral extensions other long-tailed pterosaurs possess. The paucity of early pterosaur remains has ensured that their evolutionary origin continues to be a mystery, with different experts suggesting affinities to dinosaurs, archosauriformes, or prolacertiformes.

Within the standard hypothesis that the Dinosauromorpha are the pterosaurs' close relatives within an overarching Ornithodira, Eudimorphodon is also unhelpful in establishing relationships within Pterosauria between early and later forms because then its multicusped teeth should be considered highly derived, compared to the simpler single-cusped teeth of Jurassic pterosaurs, and a strong indicator that Eudimorphodon is not closely related to the ancestor of later pterosaurs. Instead it is believed to be a member of a specialized off branch from the main "line" of pterosaur evolution, the Campylognathoididae.[2] The following phylogenetic analysis follows the topology of Upchurch et al. (2015).[6]

Eopterosauria

Preondactylus buffarinii

Austriadactylus cristatus

Peteinosaurus zambellii

Eudimorphodontidae
Raeticodactylinae

Raeticodactylus filisurensis

Caviramus schesaplanensis

Eudimorphodontinae

Arcticodactylus cromptonellus

Carniadactylus rosenfeldi

Eudimorphodon ranzii

Discovery and species

Eudimorphodon ranzii Berbenno
Fossil at Museo di Scienze Naturali, Bergamo, specimens MCSNB 8959 a,b

Eudimorphodon currently includes one species, the type species Eudimorphodon ranzii, which was first described by Zambelli in 1973. It is based on holotype MCSNB 2888. The specific name honours Professor Silvio Ranzi. A second species, Eudimorphodon rosenfeldi, was named by Dalla Vecchia in 1995 for two specimens found in Italy. However, further study by Dalla Vecchia found that these actually represented a distinct genus, which he named Carniadactylus in 2009.[7] A third species is Eudimorphodon cromptonellus, described by Jenkins and colleagues in 2001.[8] It is based on a juvenile specimen with a wingspan of just 24 centimeters, MGUH VP 3393, found in the early nineties in Jameson Land, Greenland. Its specific name honors Professor Alfred Walter Crompton; the name is a diminutive because the exemplar is so small. In 2015 it was named as a separate genus Arcticodactylus by Alexander Kellner.[9] Specimen BSP 1994 I 51, in 2003 referred to a cf E. ranzii,[10] was in 2015 by Kellner made the genus Austriadraco.[9]

In 1986 fossil jaw fragments containing multicusped teeth were found in Dockum Group rocks in western Texas. One fragment, apparently from a lower jaw, contained two teeth, each with five cusps. Another fragment, from an upper jaw, also contained several multi-cusped teeth. These finds are very similar to Eudimorphodon and may be attributable to this genus, although without better fossil remains it is impossible to be sure.[1]

Many fossils have been found that once were referred to Eudimorphodon, making Eudimorphodon represent one of the most abundant pterosaurs from Italy.[4] Today, these have largely been made separate genera.[11]

See also

References

  1. ^ a b Wellnhofer, P. (1991). "Summary of Triassic Pterosaurs." The Illustrated Encyclopedia of Pterosaurs. London, UK: Salamander Books Limited. p. 67. ISBN 0-86101-566-5.
  2. ^ a b c d e Cranfield, I. The Illustrated Directory of Dinosaurs and Other Prehistoric Creatures. London: Salamander Books, Ltd. Pp. 280-281.
  3. ^ Palmer, D., ed. (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. p. 102. ISBN 1-84028-152-9.
  4. ^ a b c Benson, R.B.J. & Brussatte, S. (2012). Prehistoric Life. London: Dorling Kindersley. pp. 216–217. ISBN 978-0-7566-9910-9.
  5. ^ Osi, A. (2010). "Feeding-related characters in basal pterosaurs: implications for jaw mechanism, dental function and diet." Lethaia, doi:10.1111/j.1502-3931.2010.00230.x
  6. ^ Upchurch, P.; Andres, B.B.; Butler, R.J.; Barrett, P.M. (2015). "An analysis of pterosaurian biogeography: implications for the evolutionary history and fossil record quality of the first flying vertebrates". Historical Biology. 27 (6): 697–717. doi:10.1080/08912963.2014.939077. PMC 4536946.
  7. ^ Dalla Vecchia, F.M. (2009). "Anatomy and systematics of the pterosaur Carniadactylus (gen. n.) rosenfeldi (Dalla Vecchia, 1995)." Rivista Italiana de Paleontologia e Stratigrafia, 115(2): 159–188.
  8. ^ Jenkins F.A., Jr., et al. (2001). "A diminutive pterosaur (Pterosauria: Eudimorphodontidae) from the Greenlandic Triassic." Bulletin of the Museum of Comparative Zoology, Harvard University, 155: 487-506.[1]
  9. ^ a b Kellner, Alexander W.A., 2015, "Comments on Triassic pterosaurs with discussion about ontogeny and description of new taxa", Anais da Academia Brasileira de Ciências 87(2): 669-689
  10. ^ Wellnhofer P., 2003, "A Late Triassic pterosaur from the Northern Calcareous Alps (Tyrol, Austria)". In: Buffetaut E. and Mazin J-M. (Eds), Evolution and Palaeobiology of Pterosaurs, Geological Society of London, Special Publications 217, pp 5-22
  11. ^ Dalla Vecchia, Fabio Marco, 2019, "Seazzadactylus venieri gen. et sp. nov., a new pterosaur (Diapsida: Pterosauria) from the Upper Triassic (Norian) of northeastern Italy". PeerJ 7: e7363
  • Dixon, Dougal. "The Complete Book of Dinosaurs." Hermes House, 2006.
  • Fantastic Facts About Dinosaurs (ISBN 0-7525-3166-2)
Arcticodactylus

Arcticodactylus is a genus of basal pterosaur living during the Late Triassic in the area of present Greenland. Its only species was previously attributed to Eudimorphodon, and its closest relatives may have been Eudimorphodon or Austriadraco.

Austriadactylus

Austriadactylus is a genus of "rhamphorhynchoid" pterosaur. The fossil remains were unearthed in Late Triassic (middle Norian age) rocks of Austria.

The genus was named in 2002 by Fabio Marco Dalla Vecchia e.a.. The type species is Austriadactylus cristatus. The genus name is derived from Latin Austria and Greek daktylos, "finger", in reference to the wing finger of pterosaurs. The specific epithet means "crested" in Latin, a reference to the skull crest.

The genus is based on holotype SMNS 56342, a crushed partial skeleton on a slab, found in an abandoned mine near Ankerschlag in Tyrol, in the Norian Seefelder Beds. The counterslab has been lost and with it some of the bone. The fossil consists of the skull, lower jaws, some vertebrae, parts of the limbs and pelvic girdle, and the first part of the tail.

The elongated skull has a length of 11 cm. It carried a bony crest that widened as it descended towards the snout, up to height of 2 cm. The triangular nares formed the largest skull openings. The also triangular fenestrae antorbitales are smaller than the orbits. The teeth differ in shape and the species was thus heterodont. Most teeth are small and tricuspid or three-pointed. In the front of the upper jaw five larger recurved teeth with a single point form a prey grab; six or seven such teeth are also interspersed with the smaller teeth more to the back of the mouth. There are at least seventeen and perhaps as much as 25 tricuspid teeth in the upper jaw, for a total of perhaps 74 teeth of all sizes in the skull. The number of teeth in the lower jaws cannot be determined.

The flexible tail did not have the stiffening rod-like vertebral extensions present in other basal pterosaurs. The wingspan has been estimated at about 120 cm.

Austriadactylus was in 2002 assigned by the describers to a general Pterosauria incertae sedis, but some later analyses showed it to have been related to Campylognathoides and Eudimorphodon in the Campylognathoididae. It has even been suggested it was a junior synonym of Eudimorphodon, though perhaps a distinct species in that genus. The following phylogenetic analysis follows the topology of Upchurch et al. (2015).

Austriadraco

Austriadraco is a genus of pterosaur living during the Late Triassic in the area of present Austria. Its only species—Austriadraco dallavecchiai—was previously attributed to Eudimorphodon, and its closest relatives may have been Eudimorphodon or Arcticodactylus.In June 1994, near Seefeld in Austrian Tirol, at a 1600 metres high mountain trail to the Reither Spitze, in the vicinity of the Reither Joch-Alm, Bernd Lammerer discovered a pterosaur skeleton. The remains have been secured as five stone plates, removed on several occasions. In 2003, Peter Wellnhofer identified the fossil as a specimen of Eudimorphodon, a cf. E. ranzii. As it was 10 to 25% shorter than the latter's holotype, Wellnhofer considered it a juvenile. The same year Fabio Marco Dalla Vecchia doubted the comparability to E. ranzii and suggested that it represent a separate Eudimorphodon species. In 2009, Dalla Vecchia concluded that the specimen was neither a juvenile nor closely related to Eudimorphodon.In 2015, Alexander Kellner named the separate genus Austriadraco, with the type species Austriadraco dallavecchiai. The generic name is a combination of the Latin words Austria and draco, "dragon". The specific name honours Dalla Vecchia. The Life Science Identifiers are for the genus 120B3003-6DE3-41B4-AF6B-6F242FB2A777 and for the species 6E123721-07EA-419CB755-9981CC7D9209.The holotype, BSP 1994 I 51, was found in a layer of the Seefeld Formation, dating from the late Norian. It consists of a partial and disarticulated skeleton with skull. It contains both frontal bones, a left jugal, the lower jaws, loose teeth, vertebrae of the neck, back and tail, the shoulder girdle, both humeri, a first wing phalanx, the pelvis, a shinbone and a calf bone. The fused frontals had in 2003 been incorrectly identified as a breast bone by Wellnhofer. The bones have been partly preserved as impressions only and many are fragmented. The fossil is part of the collection of the Bayerische Staatssammlung für Paläontologie und historische Geologie at Munich.Austriadraco dallavecchiai is a small species. Humerus length is about four centimetres. In 2015 Kellner indicated several distinguishing traits. Some of these are autapomorphies. The frontal bone has a short front branch. The jugal bone has short branches to the front, in the direction of the maxilla and the nasal bone, and a long narrow upwards branch running towards the postorbital bone. In the outer rear side of the lower jaw an opening is present, the mandibular fenestra. The coronoid process of the surangular bone is low. The shoulder blade is considerably longer, 62%, than the coracoid.Additionally, a unique combination of in themselves not unique traits is present. The coracoid is broad, with a constricted shaft. In the pelvis, the ischipubic plate, the fusion of the pubic bone with the ischium, is deep. The shinbone is relatively long, with a length of 57.7 millimetres attaining 70% of the length of the humerus and 92% of the length of the first phalanx of the (fourth) wingfinger.According to Dalla Vecchia's analysis, Austriadraco would have a very basal position in the Pterosauria. Kellner concluded that its affinities were uncertain and placed Austriadraco in a separate, undefined, Austriadraconidae. He suggested a close relationship with Arcticodactylus as both taxa shared the trait of a short coracoid.

Averostra

Averostra, or "bird snouts", is a clade that includes most theropod dinosaurs that have a promaxillary fenestra (fenestra promaxillaris), an extra opening in the front outer side of the maxilla, the bone that makes up the upper jaw. Two groups of averostrans, the Ceratosauria and the Orionides, survived into the Cretaceous period. When the Cretaceous–Paleogene extinction event occurred, ceratosaurians and two groups of orionideans within the clade Coelurosauria, the Tyrannosauroidea and Maniraptoriformes, were still extant. Only one subgroup of maniraptoriformes, Aves, survived the extinction event and persisted to the present day.

Avetheropoda

Avetheropoda, or "bird theropods", is a clade that includes carnosaurians and coelurosaurs to the exclusion of other dinosaurs.

Bergamodactylus

Bergamodactylus is a genus of basal pterosaur living during the Late Triassic (early Norian) in the area of present-day Bergamo province in Italy. Its only species is Bergamodactylus wildi. It was previously regarded as a juvenile Eudimorphodon or as identical to Carniadactylus.In 1978, Rupert Wild described a small pterosaur specimen in the collection of the Museo di Paleontologia dell´Università di Milano, found near Cene in Lombardy. He referred to it as the "Milan Exemplar" and identified it as a juvenile of Eudimorphodon ranzii. Wild noted considerable differences with the latter's type specimen but these were explained as reflecting the young age of the animal.In 2009, Fabio Marco Dalla Vecchia confirmed an earlier conclusion by Alexander Kellner that the specimen must have been at least subadult in view of the fusion of the scapula and the coracoid, the upper wristbones being fused into a syncarpal, and the fusion of the extensor process on the first wing phalanx. Dalla Vecchia referred the specimen to Carniadactylus.In 2015, Kellner concluded that the Milan Exemplar represented a different species from Carniadactylus. It showed differences in build that could not be explained by individual variation, it was much smaller though of similar age, and it was of a younger geological age. He named a separate genus and species Bergamodactylus wildi. The generic name combines a reference to Bergamo with a Greek δάκτυλος, daktylos, "finger", a usual suffix in pterosaur names since Pterodactylus. The specific name honours Wild.The holotype, MPUM 6009, was found in a layer of the Calcari di Zorzino Formation dating from the early Norian (upper Alaunian). It consists of a partial skeleton including the skull, compressed on a single plate. It is largely articulated and includes the lower jaws, most of the wings, much of the vertebral column except the tail, and hindlimb elements. Some bones have only been preserved as impressions.Bergamodactylus is one of the smallest known pterosaurs: Kellner in 2015 estimated the wingspan at just 465 millimetres. He also established some distinguishing traits. The postorbital bone is slender with a thin branch towards the frontal bone. The praemaxilla does not reach the lower rim of the external nostril. The fourth metacarpal is short, with only 40% of the length of the humerus and 30% of the length of the ulna. The thighbone is short, attaining just half of the length of either the ulna or the first wing finger phalanx.Bergamodactylus has multi-cusped teeth like Eudimorphodon but their number strongly differs: fourteen in both the upper jaw and the lower jaw as against respectively twenty-nine and twenty-eight in the latter species. Additional differences with Carniadactylus include a tooth row that extends further to the rear, a lower mandibula, a higher placed deltopectoral crest on the humerus and a shorter upper part of the kinked pteroid. Bergamodactylus has a short second phalanx of the wing finger in common with Carniadactylus.Kellner placed Bergamodactylus, within the Novialoidea, in the Campylognathoidea.

Campylognathoides

Campylognathoides ("curved jaw", Strand 1928) is a genus of pterosaur, discovered in the Württemberg Lias deposits (dated to the early Toarcian age) of Germany; this first specimen consisted however only of wing fragments. Further better preserved specimens were found in the Holzmaden shale: basing on these specimens Felix Plieninger erected a new genus.

Carniadactylus

Carniadactylus is a genus of pterosaur which existed in Europe during the Late Triassic period (late Carnian or early Norian, about 228 million years ago). The genus contains a single species, Carniadactylus rosenfeldi.

Caviramus

Caviramus is a genus of "rhamphorhynchoid" pterosaur from the Late Triassic (late Norian-early Rhaetian-age) lower Kössen Formation of the Northern Calcareous Alps of Switzerland.

The genus was in 2006 named by Nadia Fröbisch and Jörg Fröbisch. The type species is Caviramus schesaplanensis. The genus name is derived from Latin cavus, "hollow" and ramus, "branch". The specific name refers to Mount Schesaplana.

Eopterosauria

Eopterosauria is a group of basal pterosaurs from the Triassic, which form their own clade. The term was first used in Andres et al. (2014) to include Preondactylus, Austriadactylus, Peteinosaurus and Eudimorphodontidae. Inside the group were two other new clades, Preondactylia, which included Preondactylus and Austriadactylus, and Eudimorphodontoidea, to include Eudimorphodontidae and Raeticodactylidae. Eopterosauria was defined as "the least inclusive clade containing Preondactylus buffarinii and Eudimorphodon ranzii". The specimen BSP 1994, previously assigned to Eudimorphodon, was named the separate taxon Austriadraco in 2015, and assigned to the new family Austriadraconidae, but further classification was not described. The following phylogenetic analysis follows the topology of Andres et al. (2014).

Eudimorphodontidae

Eudimorphodontidae is an extinct family of early pterosaurs from the Late Triassic (early Norian to Rhaetian age) of Europe. It was named by Peter Wellnhofer in 1978 to include Eudimorphodon ranzii. Some phylogenetic analyses suggested that Eudimorphodontidae is a junior synonym of Campylognathoididae, however more comprehensive analyses found Eudimorphodontidae to be basal to Macronychoptera that includes Campylognathoididae and more derived pterosaurs (Breviquartossa). Wang et al. (2009) found Eudimorphodontidae to include six species (the monospecific Peteinosaurus, Raeticodactylus and Caviramus, and three species of Eudimorphodon), but they didn't defined the clade. Brian Andres (2010, in press) define Eudimorphodontidae and found Peteinosaurus to be most closely related to it. Furthermore, he found monophyletic Eudimorphodon clade (unlike Wang et al., 2009 and Dalla Vecchia, 2009), and defined two subfamilies within Eudimorphodontidae. The Eudimorphodontinae includes all taxa more closely related to Eudimorphodon ranzii than to Raeticodactylus filisurensis while the Raeticodactylinae includes all taxa more closely related to Raeticodactylus filisurensis than to Eudimorphodon ranzii. More recently, Raeticodactylus and Caviramus were moved into their own family, Raeticodactylidae. The below cladogram follows that analysis.

Norian

The Norian is a division of the Triassic geological period. It has the rank of an age (geochronology) or stage (chronostratigraphy). The Norian lasted from ~227 to 208.5 million years ago. It was preceded by the Carnian and succeeded by the Rhaetian.

Novialoidea

Novialoidea (meaning "new wings") is an extinct clade of macronychopteran pterosaurs that lived from the latest Early Jurassic to the latest Late Cretaceous (early Toarcian to late Maastrichtian age), their fossils having been found on all continents except Antarctica. It was named by Alexander Wilhelm Armin Kellner in 2003 as a node-based taxon consisting of the last common ancestor of Campylognathoides, Quetzalcoatlus and all its descendants. This name was derived from Latin novus "new", and ala, "wing", in reference to the wing synapomorphies that the members of the clade possess. Unwin (2003) named Lonchognatha in the same issue of the journal that published Novialoidea (Geological Society of London, Special Publications 217) and defined it as Eudimorphodon ranzii, Rhamphorhynchus muensteri, their most recent common ancestor and all its descendants (as a node-based taxon). Under Unwin's and Kellner's phylogenetic analyses (where Eudimorphodon and Campylognathoides form a family that basal to both Rhamphorhynchus and Quetzalcoatlus), and because Novialoidea was named first (in pages 105-137, while Lonchognatha was named in pages 139-190), Lonchognatha is an objective junior synonym of the former. However, other analyses find Lonchognatha to be valid (Andres et al., 2010) or synonymous with the Pterosauria (Andres, 2010 and Andres, in press).

Peteinosaurus

Peteinosaurus ( peh-TY-nə-SOR-əs; meaning "winged lizard") was a prehistoric genus of Pterosaur. It lived in the late Triassic period in the late Norian age (about 221 to 210 million years ago), and at a wingspan of around 60 cm (24 in), was one of the smallest and earliest Pterosaurs.

Phylogeny of pterosaurs

This phylogeny of pterosaurs entails the various phylogenetic trees used to classify pterosaurs throughout the years and varying views of these animals. Pterosaur phylogeny is currently highly contested and several hypotheses are presented below.

Prehistoric reptile

The term prehistoric reptile covers a broad category that is intended to help distinguish the dinosaurs from other prehistoric reptiles. As the dinosaurs, because of their long and successful reign for many millions of years, are almost exclusively dealt with in their own category of prehistoric life.

The category covers all the non-dinosaurian reptiles which are often erroneously considered to be dinosaurs, such as the seafaring varieties of plesiosaurs and the flying pterosaurs. Also included are ancient crocodiles such as Deinosuchus.

For information on the synapsids, which were previously known as "mammal-like reptiles" (including the well-known Dimetrodon), which are not part of the clade Sauropsida (with which "Reptilia" is generally synonymized), see Synapsid (amniotes related to mammals). For information on the ancestors of reptiles, traditionally classified as labyrinthodont amphibians, see Reptiliomorpha (reptile-like tetrapods).

Preondactylus

Preondactylus is a genus of long-tailed pterosaurs from the Late Triassic (late Carnian or early Norian age, about 228 million years ago) that inhabited what is now Italy. It contains a single known species, Preondactylus buffarinii, which was discovered by Nando Buffarini in 1982 at the Forni Dolostone near Udine in the Preone valley of the Italian Alps.

Raeticodactylidae

Raeticodactylidae is a family of eudimorphodontoid eopterosaurian pterosaurs that lived in Switzerland during the Late Triassic. The family includes Caviramus, and the type genus Raeticodactylus, which are both known from the Kössen Formation, around 205 mya. Raeticodactylidae was first used in 2014 by Andres et al., as a group of all pterosaurs closer to Raeticodactylus than Eudimorphodon. The following phylogenetic analysis follows the topology of Andres et al. (2014).

Raeticodactylus

Raeticodactylus is a genus of non-pterodactyloid pterosaur from the late Norian-early Rhaetian-age Upper Triassic lower Kössen Formation of the central Austroalpine of Grisons, Switzerland. It is known from holotype BNM 14524, a single disarticulated partial skeleton including an almost complete skull, found in August 2005. This genus was named and described in 2008 by its discoverer Rico Stecher; the type species is Raeticodactylus filisurensis. The specific name refers to Filisur.

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