Dysalotosaurus

Dysalotosaurus
Skeleton reconstruction of Dysalotosaurus in the Berlin Museum of Natural History
Temporal occurrence
Upper Jurassic (late Kimmeridgian to early Tithonian )
154.7 to 147.7 million years
Locations
Tanzania ( Tendaguru formation )
Systematics
Dinosaur (dinosauria) Pelvic dinosaur (Ornithischia) Ornithopoda Dryosauridae Dysalotosaurus
Scientific name
Dysalotosaurus
Virchow , 1919
Art
Dysalotosaurus lettowvorbecki

Side view of the skeleton

Dysalotosaurus is a genus of ornithopod dinosaur from the group of Dryosauridae . It was a medium-sized, two-legged herbivore or omnivore thatlived in Africaduring the Upper Jurassic (late Kimmeridgian to early Tithonian ).

Numerous, partly well-preserved remains of this genus come from the famous Tendaguru site in Tanzania and make Dysalotosaurus one of the best-known Jurassic ornithopods, although numerous fossils were lost in the Second World War. For a long time Dysalotosaurus was regarded as a synonym for Dryosaurus - however, recent studies consider Dysalotosaurus as a valid, independent genus. The only species is Dysalotosaurus lettowvorbecki (an outdated spelling is lettow-vorbecki).

Naming

Dysalotosaurus was scientifically described in 1919 by the German scientist Hans Virchow with the only species Dysalotosaurus lettowvorbecki to date . The name means something like "difficult to catch lizard" ( Greek δυσάλωτος dysálōto | s [<δυσ- "miss-, evil-" and ἁλωτός hallōtós , verbal adjective of ἁλίσκωμαι "will be caught"] "difficult to catch" and σαύραú | ā "lizard"; - us is the Latin ending morphem ), and is probably intended to allude to the animal's light build . The second part of the species name, lettowvorbecki honors Paul von Lettow-Vorbeck , a German officer who during the First World War in German East Africa has commanded.

Finds and research history

The fossils were discovered and excavated by expeditions carried out by the Berlin Museum of Natural History at the beginning of the 20th century in the former German East Africa around a hill called Tendaguru . These expeditions unearthed numerous dinosaur finds, including several sauropods such as Giraffatitan and Dicraeosaurus , the stegosaur Kentrosaurus or the theropod Elaphrosaurus . Although dinosaur finds come from several dozen different quarries around Tendaguru Hill, all of the Dysalotosaurus fossils were discovered in just one quarry. From 1910 to 1913, under the direction of H. Reck, over 14,000 finds were recovered from this quarry, most of which represent individual bones, but also include some connected skeletons. This quarry, located about 2.5 kilometers northwest of Tendaguru Hill near the settlement of Kindope, belongs to the middle dinosaur layers of the Tendaguru Formation.

Numerous Dysalotosaurus fossils were lost in bombing raids on Germany during World War II . Most of the best preserved skeletons are only known today through drawings and sketches.

Features and ontogeny

The known fossils of the Dysalotosaurus come from animals of various ages, the smallest specimen being 0.7 meters and the largest specimen being 5 meters long. A developmental study by Tom Huebner and Oliver Rauhut (2010) reconstructed the change in characteristics during growth: Compared to adult animals, for example, young animals have shorter snouts and larger eye sockets (orbita). The dentition shows further age-related changes: For example, young animals only had 10 teeth per half of their jaws in the lower and upper jaw, while adult animals had 13 teeth. The teeth also became wider and wider as the individual developed. The foremost three teeth on each half of the jaw in young animals were significantly slimmer than the other teeth - such a heterodontia is not known from adult specimens. These changes could indicate that young animals were omnivores and that the animals did not become pure herbivores until they reached adulthood.

Oldest evidence of viral infection

In 2011, Florian Witzmann and Oliver Hampe from the Berlin Museum für Naturkunde examined a pathological thickening on a vertebra of Dysalotosaurus and came to the conclusion that it was Paget's syndrome (osteodystrophia deformans), a disease likely caused by a Viral infection . This would be the oldest evidence of a virus infection at all.

Systematics

Dysalotosaurus is one of the Dryosauridae , a basal (original) group within the Iguanodontia . Barrett (2011) summarizes Dysalotosaurus with the genera Valdosaurus and Elrhazosaurus to form a clade within the Dryosauridae, based on similarities in the upper metatarsal bones.

Current cladogram example (simplified from Barrett, 2011):

Dryosauridae	Callovosaurus      Kangnasaurus      Dryosaurus      Dysalotosaurus      Valdosaurus      Elrhazosaurus

Individual evidence

1. ^ Gregory S. Paul: The Princeton Field Guide To Dinosaurs . In: Princeton University Press, Princeton NJ et al. 2010, ISBN 978-0-691-13720-9 .  ( Page no longer available , search in web archives )  Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.  
2. ↑ ^{a b c d e} Tom R. Hübner, Oliver WM Rauhut : A juvenile skull of Dysalotosaurus lettowvorbecki (Ornithischia: Iguanodontia), and implications for cranial ontogeny, phylogeny, and taxonomy in ornithopod dinosaurs. In: Zoological Journal of the Linnean Society. Vol. 160, No. 2, 2010, ISSN  0024-4082 , pp. 366-396, doi : 10.1111 / j.1096-3642.2010.00620.x .
3. ^ ^{A b} Paul M. Barrett , Richard J. Butler, Richard J. Twitchett, Stephen Hutt: New material of Valdosaurus canaliculatus (Ornithischia: Ornithopoda) from the Lower Cretaceous of southern England. In: Special Papers in Palaeontology. Vol. 86, 2011, ISSN  0038-6804 , pp. 131-163.
4. ↑ Hans Virchow : Atlas and Epistropheus with the tortoises. In: Meeting reports of the Society of Friends of Natural Sciences in Berlin. No. 8, 1919, ISSN  0037-5942 , pp. 303-332, digitized .
5. ↑ Ben Creisler: Dinosauria Translation and Pronunciation Guide ( Memento of October 13, 2011 in the Internet Archive )
6. ^ Peter M. Galton : Dryosaurus, a hypsilophodontid dinosaur from the Upper Jurassic of North America and Africa. Postcranial skeleton. In: Paleontological Journal. Vol. 55, No. 3/4, 1981, ISSN  0031-0220 , pp. 271-312, doi : 10.1007 / BF02988144 .
7. ↑ Tom Hübner: first results of a palaeobiological study . The Annual Symposium of Vertebrate Palaeontology and Comparative Anatomy. 2007. Archived from the original on March 4, 2016. Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Retrieved September 26, 2014. 
8. ↑ Florian Witzmann, Kerin M. Claeson, Oliver Hampe, Frank Wieder, André Hilger, Ingo Manke, Manuel Niederhagen, Bruce M. Rothschild, Patrick Asbach: Paget disease of bone in a Jurassic dinosaur. In: Current Biology. Vol. 21, No. 17, 2011, ISSN  0960-9822 , pp. R647-R648, doi : 10.1016 / j.cub.2011.08.006 .