Umoonasaurus
| Umoonasaurus | ||||||||||||
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Umoonasaurus , drawing reconstruction |
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| Temporal occurrence | ||||||||||||
| Lower Cretaceous ( Aptium to Albium ) | ||||||||||||
| 126.3 to 100.5 million years | ||||||||||||
| Locations | ||||||||||||
| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Umoonasaurus | ||||||||||||
| Kear et al., 2006 | ||||||||||||
Umoonasaurus is a genus of pliosaurs (Pliosauridae), extinct diapsid reptiles from the Lower Cretaceous of southern Australia . The only known species is Umoonasaurus demoscyllus , of which an almost complete and about 85 percent opalized skeleton and several partial skeletons have been found. The opal skeleton is also the most completely opalized skeleton of a vertebrate that is known worldwide.
features
Umoonasaurus was a relatively small pliosaur with a body length of about 2.5 meters. The distinguishing feature over other plesiosaurs is the existence of a bone crest along the midline of the skull as well as a pair of bone crests above the eyes.
Unlike other Rhomaleosauridae , some typical features of the Jura representatives of the group were not developed in this genus. These include the large head and short neck as well as the tendency to gigantism, i.e. to develop giant forms, as was the case with the approximately seven-meter-long Rhomaleosaurus .
Paleoecology
Umoonasaurus lived together with other plesoisaurs and some ichthyosaurs in cold water, which was seasonally characterized by temperatures close to freezing point. This is in stark contrast to the climatic conditions that recent aquatic reptiles can tolerate. The forms must have been adapted to these conditions accordingly, for example through specialized physiological mechanisms such as endothermia or behavioral strategies such as seasonal migrations. Umoonasaurus was also obviously endemic to the Bulldog shale in what is now South Australia.
Taxonomy and systematics
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Phylogenetic systematics of the Rhomaleosauridae
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The opalized skeleton was found in 1987 by a miner in Coober Pedy in the Eromanga Basin (the former Eromanga Sea) and sold to the opal dealer Andrew Cody in Melbourne , who first kept it in his private collection. In 1993 the skeleton was bought by the Australian Museum in Sydney . There it is exhibited under the nickname 'Eric'. The first description of the species was carried out only in 2006 by the Australian paleontologist Benjamin Kear P. and colleagues in the Biology letters . The first description was carried out on the basis of the skeleton (Australian Museum F99374) described as holotype , another, also opal adult individual in the South Australian Museum (P23841), a third skeleton from the region Curdimurka (P31050) and a cub from the region Neale River . All sites are in the Bulldog Slate in northern South Australia , which are assigned to the Lower Aptium to the Lower Albium .
Despite its relatively young age of around 115 million years, Umoonasaurus is assigned to the early and original pliosaurs (Pliosauroidea). It is assumed that it is both the most original and the longest surviving representative of the Rhomaleosauridae .
The generic name Umoonasaurus is made up of the words Umoona , which in the Aboriginal language Antakirinja designates the area around the site of Coober Pedy, and the Greek sauros (σαῦρος) for "lizard". The species name demoscyllus consists of the Greek demos (δῆμος) for "people" or "community" and Scylla (Σκύλλα), the name of a sea monster from Greek mythology .
supporting documents
- ↑ a b c d e f g Benjamin P. Kear, Natalie I. Schroeder, Michael SY Lee: An archaic crested plesiosaur in opal from the Lower Cretaceous high-latitude deposits of Australia. In: Biology letters. Volume 2, number 4, December 2006, pp. 615-619, doi : 10.1098 / rsbl.2006.0504 , PMID 17148303 , PMC 1833998 (free full text).
- ↑ Even a ferocioss pliosaur Becomes a real gem in time. The Age, April 9, 1987.
- ↑ Omoonasaurus demoscyllus on the Australian Museum homepage.
literature
- Benjamin P. Kear, Natalie I. Schroeder, Michael SY Lee: An archaic crested plesiosaur in opal from the Lower Cretaceous high-latitude deposits of Australia. In: Biology letters. Volume 2, number 4, December 2006, pp. 615-619, doi : 10.1098 / rsbl.2006.0504 , PMID 17148303 , PMC 1833998 (free full text).
Web links
- Omoonasaurus demoscyllus on the Australia Museum website.