Arcticodactylus

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Not to be confused with Artiodactyl.

Arcticodactylus
Temporal range:
Ma
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Order: †Pterosauria
Family: †Eudimorphodontidae
Genus: †Arcticodactylus
Kellner, 2015
Species:
†A. cromptonellus
Binomial name
†Arcticodactylus cromptonellus
(Jenkins et al., 2001)
Synonyms

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.

History of discovery

In 1989,

Alfred Walter Crompton. The suffix ~ellus, in Latin indicating a diminutive, alluded to the small size of the specimen.[1]

The holotype, MGUH VP 3393, was found in the Carlsberg Fjord Beds of the Ørsted Dal Member of the Fleming Fjord Formation dating from the Norian – Rhaetian. It consists of a partial skeleton with skull. It is largely disarticulated.[1]

The reference to Eudimorphodon had been essentially based on the similarity in tooth form, especially the distinctive multi-cuspid build with three, four or five points on the crown. In 2003,

Life Science Identifier is 72AE012A-018A-4B4B-950F-3CCB4C1D2471. The type species is Eudimorphodon cromptonellus, the combinatio nova is Arcticodactylus cromptonellus.[4]

Description

The holotype individual of Arcticodactylus is the smallest pterosaur known, with an estimated

histological research of its bone structure, considered not to have been full-grown yet, though not newly born.[1]

In 2015, Kellner established some distinguishing traits, correcting and adding to the 2001 diagnosis. The jaws have eleven or twelve multi-cusped teeth per side. The articulation surface of the fourth

metatarsal of the foot is elongated with 56% of shinbone length. These proportions imply that Arcticodactylus had relatively short wings and large feet.[4]

Arcticodactylus can furthermore be distinguished from Eudimorphodon in the lack of long fang-like teeth in the middle of the tooth row and from Eudimorphodon ranzii, Carniadactylus and Bergamodactylus by a triangular instead of rectangular deltopectoral crest on the humerus. Articodactylus has fewer teeth than any other known Triassic pterosaur.[4]

Jenkins e.a. claimed that the unique articulation in Arcticodactylus between the main wing metacarpal and the wing finger, with two rounded condyles, was a transitional shape between the ancestral form that featured a single rounded articulation surface on the metacarpal allowing a considerable amount of lateral movement, and the condition in later pterosaurs that showed a gentle depression or trochlea. The two condyles, the upper one the largest, would have forced the finger into the most optimal plane of movement during the upstroke of the wing.[1]

Classification

In 2001, E. cromptonellus was placed in the

Austriadraconidae. According to Kellner, the original describers had incorrectly identified a coracoid as a quadrate bone.[4] The following phylogenetic analysis follows the topology of Upchurch et al. (2015).[5]

Eopterosauria

Preondactylus buffarinii

Austriadactylus cristatus

Peteinosaurus zambellii

Eudimorphodontoidea
Raeticodactylidae

Raeticodactylus filisurensis

Caviramus schesaplanensis

Eudimorphodontidae

Arcticodactylus cromptonellus

Carniadactylus rosenfeldi

Eudimorphodon ranzii

In 2020 however, a study upheld by Matthew G. Baron about early pterosaur interrelationships found Arcticodactylus to group with Carniadactylus, Raeticodactylus, and the Austriadraconidae, which in turn were within a clade he called Caviramidae.[6]

See also

References

  1. ^ a b c d e Jenkins, F. A. Jr.; Shubin, N. H.; Gatesy, S. M.; Padian, K. (2001). "A diminutive pterosaur (Pterosauria: Eudimorphodontidae) from the Greenlandic Triassic". Bulletin of the Museum of Comparative Zoology. 156: 151–170.
  2. ^ Kellner, A.W.A., 2003, "Pterosaur phylogeny and comments on the evolutionary history of the group". In: Buffetaut E. and Mazin J-M. (Eds), Evolution and Palaeobiology of Pterosaurs. Geological Society of London, Special Publications 217, pp. 105-137
  3. ^ Dalla Vecchia F.M., 2014, Gli pterosauri triassici, Memorie del Museo Friulano di Storia Naturale, pubblicazione numero 54, 319 p., 266 figs, Museo Friulano di Storia Naturale, Udine
  4. ^
    PMID 26131631
    .
  5. PMID 26339122
    .
  6. PMID 33005485
    .
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