Malawisaurus
| Malawisaurus | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Live reconstruction of the head of Malawisaurus dixeyi . |
||||||||||||
| Temporal occurrence | ||||||||||||
| Lower Cretaceous ( Aptium ) | ||||||||||||
| 126.3 to 112.9 million years | ||||||||||||
| Locations | ||||||||||||
|
||||||||||||
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name | ||||||||||||
| Malawisaurus | ||||||||||||
| Jacobs , Winkler , Downs & Gomani , 1993 | ||||||||||||
| Art | ||||||||||||
|
Malawisaurus is a genus of sauropod dinosaur from the Titanosauria group thatlived in Africaduring the Lower Cretaceous . Fossil remains come from northern Malawi and include not only the bones of the postcranium (residual skeleton) but also parts of the skull, which is a rarity for sauropods. Malawisaurus was characterized by a short and high skull; the body was covered with skin bone plates (osteoderms). It was a very basal (original) Titanosauria. The only known species is Malawisaurus dixeyi .
features
Malawisaurus was a four-legged herbivore about 16 meters long with a long neck and tail. The skull bones suggest a short and tall skull, more similar to those of Brachiosaurus and Camarasaurus than the low and elongated skulls of derived (advanced) titanosaurs. The muzzle was high, short and blunt, as indicated by the relatively high intermaxillary bone (premaxillary). The row of teeth extended two-thirds the length of the lower jaw, in contrast to more derivative titanosaurs, in which the teeth were confined to the foremost area of the snout. On each side of the paired lower jaw sat 15 teeth, which were relatively wide compared to more derived Titanosauria, but not spoon-shaped as in Camarasaurus and Brachiosaurus .
The rest of the skeleton was characterized as in many other Titanosauria by strongly procoele ( concave on the front ) front caudal vertebrae and six sacral vertebrae. Two types of osteoderms were found: In addition to small, scale-shaped elements, a larger plate 19 cm long and 9.5 cm wide was discovered. The osteoderms are similar to those of Saltasaurus . Malawisaurus can be distinguished from all other genera by an autapomorphy on the intermaxillary bone: The ascending process of this bone is vertically aligned and is very close to the tip of the snout.
Systematics
Malawisaurus is considered in almost all studies as one of the most primal Titanosauria - only Andesaurus seems to occupy an even more primal position. Deviating from this consensus, however, two studies suggest that Malawisaurus was more closely related to Saltasaurus and Neuquensaurus than Opisthocoelicaudia is.
Research history and finds
The first find was described by Sidney Henry Haughton in 1928 as a new species of the genus Gigantosaurus - as Gigantosaurus dixeyi . The genus Gigantosaurus was described by Eberhard Fraas as early as 1908 , based on fossils from the famous Tendaguru site in Tanzania . Fraas described two species of this genus - the type species Gigantosaurus africanus and Gigantosaurus robustus . As it turned out later, however, the name Gigantosaurus was already given to another sauropod from England, whereupon the genus was subsequently renamed Tornieria (Sternfeld, 1911) - the three species have since been listed as Tornieria robusta , Tornieria africana and Tornieria dixeyi . The species Tornieria robusta is now run as a separate genus under the name Janenschia , with Tornieria africana being the only Tornieria species that is valid today .
The Malawian species Tornieria dixeyi was newly described in 1993 as a separate genus by researchers around Louis L. Jacobs - as Malawisaurus dixeyi . The name refers to the country of Malawi , where the fossils were discovered. The find, as already described by Haughton, consists of an anterior caudal vertebra, a right pubis , a fragmentary shoulder blade (scapula) and breastbones (sternum). The anterior caudal vertebra was selected as the holotype for Malawisaurus (specimen number SAM 7405). In addition, Jacobs and colleagues wrote an incisive bone (premaxilla), a lower jaw (dental), teeth, some vertebrae, sternum and a new style ischial (ischium) to. The finds come from the Mwakasyunguti area in northern Malawi; the rock layers - the so-called dinosaur beds - belong to the Lupata group .
Additional Malawisaurus fossils were recovered in 1987, 1989, 1990 and 1992 from excursions by the Malawi Dinosaur Project , a joint venture between the Malawian Ministry of Antiquities and the Southern Methodist University in Dallas (USA). The finds come from various sites in the Mwakasyunguti area and include, among other things, various skull bones, vertebrae and elements of the limbs. These finds, as well as another contemporary genus with a longer skull, Karongasaurus , were described by Elizabeth Gomani in 2005.
Individual evidence
- ^ A b 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 .
- ↑ a b c Elizabeth M. Gomani: Sauropod dinosaurs from the Early Cretaceous of Malawi. In: Palaeontologia Electronica. Vol. 8, No. 1, 2005, ISSN 1094-8074 , Article Number 8.1.27, online .
- ^ Paul Upchurch , Paul M. Barrett , Peter Dodson : Sauropoda. In: David B. Weishampel , Peter Dodson, Halszka Osmólska (eds.): The Dinosauria . 2nd edition. University of California Press, Berkeley CA et al. 2004, ISBN 0-520-24209-2 , pp. 259-324.
- ^ Paul Upchurch: The Evolutionary History of Sauropod Dinosaurs. In: Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences. Vol. 349, No. 1330, 1995, ISSN 0080-4622 , pp. 365-390, doi : 10.1098 / rstb.1995.0125 .
- ↑ Kristina Curry Rogers: Titanosauria: A Phylogenetic Overview. In: Kristina Curry A. Rogers, Jeffrey A. Wilson (Eds.): The Sauropods. Evolution and Paleobiology. University of California Press, Berkeley CA et al. 2005, ISBN 0-520-24623-3 , pp. 50-103, doi : 10.1525 / california / 9780520246232.003.0003 .
- ↑ Jeffrey A. Wilson: An Overview of Titanosaur Evolution and Phylogeny. In: Fidel Torcida Fernández-Baldor, Pedro Huerta Hurtado (eds.): Actas de las III Jornadas Internacionales sobre Paleontología de Dinosaurios y Su Entorno. = Proceedings of the 3rd International Symposium about Paleontology of Dinosaurs and their Environment Paleontología de dinosaurios y su entorno. Salas de los Infantes (Burgos, España), 16 al 18 de septiembre de 2004. Colectivo arqueológico-paleontológico de Salas, Salas de los Infantes (Burgos, España) 2006, ISBN 84-8181-227-7 , pp. 169-190 .
- ^ Sidney H. Haughton: On some reptilian remains from the dinosaur beds of Nyasaland. In: Transactions of the Royal Society of South Africa. Vol. 16, No. 1, 1928, ISSN 0035-919X , pp. 67-75, doi : 10.1080 / 00359192809519658 .
- ^ A b Louis L. Jacobs, Dale A. Winkler, William R. Downs, Elizabeth M. Gomani: New material of an Early Cretaceous titanosaurid sauropod dinosaur from Malawi. In: Palaeontology. Vol. 36, No. 3, 1993, ISSN 0031-0239 , pp. 523-534, digitized version (PDF; 1.05 MB) ( Memento of the original from December 8, 2015 in the Internet Archive ) Info: The archive link was inserted automatically and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. .
