Austriadactylus
| Austriadactylus | ||||||||||||
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![Austriadactylus cristatus SC 332466 (A, B) and holotype SMNS 56342 (C); Scale bars 2 cm each. From: Dalla Vecchia, 2009 [1]](https://de.wikipedia.org/wiki/Datei:Austriadactylus_cristatus_skull_and_lower_jaw_from_Carnic_Prealps.jpg)
Austriadactylus cristatus SC 332466 (A, B) and holotype SMNS 56342 (C); Scale bars 2 cm each. From: Dalla Vecchia, 2009 |
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| Temporal occurrence | ||||||||||||
| Upper Triassic (Middle to Upper Norium ) | ||||||||||||
| approx. 216 to 208.5 million years | ||||||||||||
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| Scientific name | ||||||||||||
| Austriadactylus | ||||||||||||
| Dalla Vecchia et al., 2002 | ||||||||||||
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Austriadactylus is a genus of long-tailed pterosaurs from the Upper Triassic (Middle to Upper Norium approx. 216 to 208.5 million years ago). The only known species of the so far monotypical genus is Austriadactylus cristatus from the Seefeld formation in Tyrol and the approximately equally old Dolomia di Forni formation in the Friuli-Venezia Giulia region .
Etymology and history of research
The generic name refers to the place where the holotype was found in Austria (“ Austria ”) in combination with the ending “ -dactylus ”, which is often used by representatives of the pterosaurs , latinized from the ancient Greek δάκτυλος ( dáktylos = “finger”). The additional species " cristatus " ( Latin "comb-bearing") refers to the conspicuous bone crest on the skull of the pterosaur. The name of the species can roughly be translated as “Austria finger with a comb”.
The first description of the genus and type species was carried out in 2002 by Fabio Marco Dalla Vecchia and a group of co-authors on the basis of the holotype SMNS 56342, a widely articulated, nearly complete skeleton of an abandoned coal mine in the former mining area "Ankerschlag" in the town of Seefeld in Tyrol . In this mining area the rocks of the Seefeld Formation were mined for the extraction of Tyrolean rock oil or ichthyol until 1964 . In 2009, Dalla Vecchia also described a second specimen (SC 332466), also a largely articulated partial skeleton, from the Dolomia di Forni formation in the Friuli-Venezia Giulia region in Italy.
features
(Abbreviations used in the description refer to the two figures from Dalla Vecchia, 2009.)
Austriadactylus cristatus was a long-tailed pterosaur with an estimated wingspan of about 120 cm (SMNS 56342). Compared to other pterosaurs of the Triassic, the species is relatively large.
The most striking feature of Austriadactylus is a thin bone crest (“ccr”) on the skull, which extends sagittally from the tip of the snout, along the premaxilla (“pmx”), to between the eye sockets (“or”). This bone crest reaches its greatest extent with a height of approx. 2 cm (SMNS 56342) in the front area immediately in front of the nasal windows (“na”). In this area, the comb also shows a sculpture made of fine, radially arranged ribs. Austriadactylus is one of the oldest known pterosaurs with such a bone crest on the skull, along with Raeticodactylus from the Upper Triassic of Switzerland.
Another striking feature of Austriadactylus is its heterodontic dentition. The front teeth of the premaxilla ("pmxt") are large, pointed and slender. In the middle area of the maxilla (“mx”) there are one or two very large, up to 1 cm long, blade-shaped, flattened teeth with a finely sawn cutting edge (“mxt”). The also flattened teeth (“mxt”) in the rear area of the maxilla, on the other hand, are much shorter, with an approximately triangular outline and have up to 12 tiny secondary peaks along the cutting edges. The teeth ("sdt") in the front area of the lower jaw ("d") are similar to those of the premaxilla, large, pointed and slender. In the back of the lower jaw there are up to 25 small, leaf-shaped teeth (“dt”) with 4–6 small secondary tips on each of the two cutting edges. The size of these teeth decreases slightly from the front to the back of the lower jaw. Heterodontics is also known from other pterosaurs of the Upper Triassic.
Austriadactylus had a long tail. In contrast to most other long-tailed pterosaurs, the caudal spine is not stiffened by extremely elongated zygapophyses and hemapophyses , but was flexible during lifetime, as indicated by the bent and partially disarticulated caudal spine on the holotype (SMNS 56342). Austriadactylus shares this characteristic with the genus Eudimorphodon , which also comes from the Upper Triassic .
The second specimen described in 2009 (SC 332466) from Italy brought some new insights into the anatomy of the postcranial skeleton which proved to be important for the systematic assignment of Austriadactylus . The " Crista deltopectoralis " ("deltopectoral crest"), a bone ridge on the humerus ("h") that serves as a muscle attachment and is particularly strong in pterosaurs, is rounded-triangular ("subtriangular") and is more like that of Preondactylus , Peteinosaurus and Dimorphodon as the approximately square of Eudimorphodon and other representatives of the Campylognathoididae . The first finger member of the wing ( "wph 1") is shorter ( "wph 2") than the second, a feature which Austriadactylus also with preondactylus , Peteinosaurus and Dimorphodon but shares, not with the Campylognathoididae.
Systematics
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| Systematic position of Austriadactylus within the Eopterosauria according to Andres et al., 2014; |
Austriadactylus was characterized in the first description of 2002 simply as a basal representative Pterosauria . David Unwin placed Austriadactylus 2003, on the basis of the holotype (SMNS 56342), together with Eudimorphodon and Campylognathoides in the clade of the Campylognathoididae ("the last common ancestor of Eudimorphodon ranzii and Campylognathoides liasicus and all his descendants at the same time, however") this assignment is based only on very weak arguments.
Dalla Vecchia revised this analysis in the context of the description of the second specimen (SC 332466) in 2009 and placed Austriadactylus together with Preondactylus in a separate clade apart from the Campylognathoididae. In 2010, Brian Andres et al. the clade of Campylognathoididae as polyphyletic and declared them invalid.
In 2014 Andres et al. the known obertriadischen forms in the clade of Eopterosauria together and they stood against the other representatives of the pterosaur ( "Macronychoptera"). Austriadactylus was placed together with Preondactylus in the clade of Preondactylia within the Eopterosauria.
Paleecology
For Austriadactylus , as for the Eopterosauria in general, a predominantly insectivore diet is assumed.
The sediments of the Seefeld Formation were deposited in small, deep sea basins within the carbonate platform along the coasts of the western Paleotethys . Anoxic conditions prevailed at the bottom of these basins , which offered ideal conditions for fossil conservation. In addition to the inhabitants of the sea itself, carcasses of land animals and plants from the adjacent, island-like land masses that were flooded in were also preserved in fossil form in these sediments. The vegetation cover of these islands consisted mainly of conifers ( e.g. representatives of the Cheirolepidiaceae ), but also included cycads and bar moss plants and suggests a hot, arid climate. Austriadactylus shared this habitat, among others, with other representatives of the Eopterosauria and the Protorosaurier Langobardisaurus .
Individual evidence
- ↑ a b c d e f g h F. M. Dalla Vecchia: The First Italian Specimen of Austriadactylus cristatus (Diapsida, Pterosauria) from the Norian (Upper Triassic) of the Carnic Prealps. In: Rivista Italiana di Paleontologia e Stratigrafia , Vol. 115, No. 3, pp. 291–304, 2009. (digitized version )
- ↑ a b c d e f g h i j F. M. Dalla Vecchia, R. Wild, H. Hopf & J. Reitner: A Crested Rhamphorhynchoid Pterosaur from the Late Triassic of Austria. In: Journal of Vertebrate Paleontology , Vol. 22, No. 1, pp. 196–199, 2002. (digitized version)
- ↑ Federal Ministry of Science, Research and Economy: Österreichisches Montan-Handbuch 2015. 282 p., Vienna, 2015. (digitized version)
- ^ A b B. Andres, JM Clark & X. Xu: The Earliest Pterodactyloid and the Origin of the Group. In: Current Biology , Vol. 24, pp. 1011-1016, 2014. doi : 10.1016 / j.cub.2014.03.030
- ↑ DM Unwin: On the phylogeny and evolutionary history of pterosaurs. In: E. Buffetaut & J.-M. Mazin (Ed.): Evolution and Palaeobiology of Pterosaurs. Geological Society of London - Special Publications, Vol. 217, pp. 139–190, 2003. (digitized version )
- ↑ B. Andres, JM Clark & X. Xu: A new rhamphorhynchid pterosaur from the Upper Jurassic of Xinjiang, China, and the phylogenetic relationships of basal pterosaurs. In: Journal of Vertebrate Paleontology , Vol. 30, No. 1, pp. 163-187, 2010. doi : 10.1080 / 02724630903409220
- ↑ A. Ősi: Feeding related characters in basal pterosaurs: implications for jaw mechanism, dental function and diet. In: Lethaia , Vol. 44, pp. 136–152, 2010. (Abstract)
- ↑ Ch.-F. Zhou, K.-Q. Gao, H. Yi, J. Xue, Q. Li & RC Fox: Earliest filter-feeding pterosaur from the Jurassic of China and ecological evolution of Pterodactyloidea. In: Royal Society Open Science , 2017. doi : 10.1098 / rsos.160672
- ↑ E. Kustatscher, Ch.Daxer & K. Krainer: Plant fossils from the Norian Seefeld Formation (Late Triassic) of the Northern Calcareous Alps (Tyrol, Austria) and their environmental / palaeoclimatic consequences. In: New Yearbook of Geology and Paleontology - Treatises , Vol. 283, No. 3, pp. 347–363, 2017 (abstract)
- ^ F. Saller, S. Renesto & FM Dalla Vecchia: First record of Langobardisaurus (Diapsida, Protorosauria) from the Norian (Late Triassic) of Austria, and a revision of the genus. In: New Yearbook of Geology and Paleontology - Treatises , Vol. 268, No. 1, pp. 83–95, 2013. (digitized version)