Diamantinasaurus
| Diamantinasaurus | ||||||||||||
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Live reconstruction of Diamantinasaurus matildae . From Hocknull and colleagues, 2009. |
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| Temporal occurrence | ||||||||||||
| Lower Cretaceous (late Albian ) | ||||||||||||
| 107.5 to 100.5 million years | ||||||||||||
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Diamantinasaurus | ||||||||||||
| Scott A. Hocknull et al. , 2009 | ||||||||||||
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Diamantinasaurus is a genus of sauropod dinosaur from the group of titanosaur , in the Lower Cretaceous of Australia lived.
This genus was scientifically described for the first time in 2009 with the only species, Diamantinasaurus matildae . So far, a fragmentary, skullless skeleton is known, which consists of the shoulder girdle, the foreleg, the pelvis and parts of the hind legs and comes from the late Albium of the Winton Formation of Queensland .
Diamantinasaurus was a derived (modern) titanosaur belonging to the group Lithostrotia ; the same group that also includes the better known genera Opisthocoelicaudia and Saltasaurus . Unique to a derived titanosaur is the presence of a hand claw.
features
Diamantinasaurus was about 16 meters long. This genus can be distinguished from other genera by a unique combination of characteristics. The shoulder blade (scapula) was flat and rectangular in cross-section. The upper areas of the ribs were pneumatized, that is, with numerous air-filled chambers. The upper arm bone (humerus) and ulna (ulna) were very stocky - the thickness of the upper (proximal) end of the humerus was about 50% of its total length. The humerus's lower articular cartilage was flat and connected. The metacarpal bones (metacarpals) were massive, showed undivided articular knots and were rough at the lower (distal) end. As with other Titanosauria, the phalanges were greatly reduced: only four of the original five fingers had phalanges - the phalangeal formula is 2-1-1-1-0.
There was a claw (ungual) on the first finger (thumb) - this makes Diamantinasaurus the first Titanosauria to have a hand claw. The phalanx on the third finger was greatly reduced and is considered an autapomorphy of this genus (unique feature). The ilium (ilium) was massive and, like other representatives of the Titanosauriformes , showed a club-like crest on the anterior (pre-acetabular) half, which was aligned perpendicular to the axis of the sacrum . The thighbone (femur) is robust and shows the lateral hump typical of Titanosauriformes. Also shin (tibia) and fibula (fibula) were relatively robust.
Features that allow classification within the Titanosauria include, for example, the crescent-shaped breastbone (sternum). In addition, the ulna showed a bone spur at the upper end ( olecranon ), which extended over the articular surface of the ulna. Furthermore, as with other Titanosauria, the lower (distal) end of the tibia was twice as thick as the shaft.
Further features, which allow a classification within the lithostrotia show, for example, on the shoulder blade having a 45 ° angle with the coracoid forms (coracoid), and on the thigh bone, which shows a highly eccentric cross section and are not whose lower condyle perpendicular to the shaft axis , but are inclined relative to the vertical orientation. These features of the femur are believed to be related to the evolution of another leg position within the Titanosauria.
Systematics
Diamantinasaurus is classified as a derivative of the Titanosauria within the Lithostrotia group. The systematic position within the Lithostrotia remains unclear - so this genus is provisionally listed as Lithostrotia incertae sedis .
Find and naming
The bones were recovered from excavations at the Australian Age of Dinosaurs Museum of Natural History and the Queensland Museum between 2006 and 2009 . These excavations uncovered at least two more new dinosaur species at two sites: the titanosauriform Wintonotitan and the allosauroid Australovenator . Dinosaur finds from Australia are extremely rare compared to the numerous finds on other continents. However, the researchers see great potential for further discoveries in Australia.
The skeleton found ( holotype , copy number AODF 603) consists of the shoulder blade, sternum, humerus, ulna, an almost complete metatarsus, phalanxes, a claw, ribs, fragmentary abdominal ribs (gastralia), iliac bone, elements of the sacrum, pubic bone, ischium, femur , Tibia, fibula and an ankle bone (astragalus).
The skeleton comes from the "Matilda site", which is about 60 km northwest of the city of Winton in western Queensland. Stratigraphically , the rocks at the site belong to the lowest Winton Formation , which was deposited in the late Albian . The fossils were found between two layers of sandstone within a layer of clayey sediment. These sediments are used as the deposits of a Altarms - a cut-off river arm ( oxbow lake interpreted -). In addition to the Diamantinasaurus fossils, the site also contained the skeleton of Australovenator , the most complete skeleton of a theropod from Australia to date. The site also contains the remains of fish, crocodile species, turtles and mussels.
The name Diamantinasaurus ("Lizard from the Diamantina River") refers to the Diamantina River near the site. The Artepitheth matildae refers to the well-known Australian folk song " Waltzing Matilda ", which the poet Banjo Paterson wrote in Winton in 1895 and which was proposed as the official Australian national anthem .
literature
- Scott A. Hocknull, Matt A. White, Travis R. Tischler, Alex G. Cook, Naomi D. Calleja, Trish Sloan, David A. Elliott: New mid-Cretaceous (latest Albian) dinosaurs from Winton, Queensland, Australia. In: PLoS ONE . Vol. 4, No. 7, 2009, e6190, doi : 10.1371 / journal.pone.0006190 .
Web links
- Diamantinasaurus in the Paleobiology Database.
Individual evidence
- ^ Gregory S. Paul : The Princeton Field Guide To Dinosaurs. Princeton University Press, Princeton NJ et al. 2010, ISBN 978-0-691-13720-9 , p. 207, online .
- ^ Scientists Find Dinosaur That Lived 98M Years Ago in Australia . In: Associated Press . Fox News. July 3, 2009. Archived from the original on September 4, 2009. Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. Retrieved August 28, 2014.
- ↑ Jeffrey A. Wilson, Matthew T. Carrano: Titanosaurs and the Origin of "Wide-Gauge" Trackways: A Biomechanical and Systematic Perspective on Sauropod Locomotion. In: Paleobiology. Vol. 25, No. 2, 1999, ISSN 0094-8373 , pp. 252-267.
