Ignavusaurus
| Ignavusaurus | ||||||||
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| Temporal occurrence | ||||||||
| Lower Jurassic (? Hettangium ) | ||||||||
| 201.3 to 199.3 million years | ||||||||
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| Systematics | ||||||||
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| Scientific name | ||||||||
| Ignavusaurus | ||||||||
| Knoll , 2010 | ||||||||
| Art | ||||||||
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Ignavusaurus is a genus of dinosaurs from the group of Sauropodomorpha . The only species is Ignavusaurus rachelis . It was first described in 2010 on the basis of a well-preserved, partial skeleton, which comes from the Lower Jurassic Upper Elliot Formation in Lesotho . It was a very original representative of the Sauropodomorpha, which was probably more advanced than Thecodontosaurus and Pantydraco , but more original than Efraasia and Plateosaurus .
features
The only known skeleton belonged to a young animal believed to be less than a year old and in the rapid growth phase. The body length of this specimen is estimated at 1.5 meters, the weight at about 22.5 kilograms. It was a two-legged animal with a long neck and a small head, like other original sauropodomorphs.
The skull is fragmented and is present in over 120 small fragments, which makes interpretation difficult. The teeth were thin, flattened and serrated. The diversity of the teeth ( heterodontics ) was remarkable : while some teeth were tapered and unsawed, other teeth were spatula-shaped, sawed and convex on the side facing the lip . This heterodontia could indicate that Ignavusaurus was not purely herbivorous, as was the case with more advanced sauropodomorphs like Plateosaurus , but that the diet was more opportunistic (less fussy).
Systematics
In the past, the sauropodomorpha were divided into two groups: the prosauropods and the sauropods . Today the sauropods are considered the direct descendants of the prosauropods, the prosauropods therefore do not form a monophyletic group and are only rarely used today. Ignavusaurus was one of the classic "prosauropods" and was probably closely related to the direct ancestors of advanced prosauropods and sauropods. A cladistic analysis by Fabien Knoll (2010) comes to the conclusion that Ignavusaurus was more advanced than Saturnalia , Pantydraco and Thecodontosaurus , but more primitive than Efraasia , Plateosaurus and Massospondylus .
Adam Yates and colleagues (2011) suggest that Ignavusaurus was identical to Massospondylus . Researchers working with Cecilia Apaldetti (2011) accept Ignavusaurus as a valid genus - in their cladistic analysis this genus is closely related to Sarahsaurus .
Find and naming
The only skeleton comes from southern Lesotho in the Qacha's Nek district . The skeleton was recovered from a reddish siltstone and mostly found in an anatomical context.
Ignavusaurus rachelis was first scientifically described by Fabien Knoll in 2010 . The name Ignavusaurus means something like "coward lizard", from Latin ignavus - "coward", Greek sauros - "lizard", as the name of the Ha Ralekoala site can be translated as "the place of the coward's father". The second part of the species name, rachelis , is the Latinized form of the name Raquel and honors the paleontologist Raquel López-Antoǹanzas .
Individual evidence
- ↑ a b c d e f Fabien Knoll: A primitive sauropodomorph from the upper Elliot Formation of Lesotho. In: Geological Magazine. Vol. 147, No. 6, ISSN 0016-7568 , pp. 814-829, doi : 10.1017 / S001675681000018X .
- ^ Adam M. Yates, Matthew F. Bonnan, Johann Neveling: A new basal sauropodomorph dinosaur from the Early Jurassic of South Africa. In: Journal of Vertebrate Paleontology. Vol. 31, No. 3, 2011, ISSN 1522-2152 , pp. 610-625, doi : 10.1080 / 02724634.2011.560626 .
- ↑ Cecilia Apaldetti, Ricardo N. Martinez, Oscar A. Alcober, Diego Pol: A New Basal Sauropodomorph (Dinosauria: Saurischia) from Quebrada del Barro Formation (Marayes-El Carrizal Basin), Northwestern Argentina. In: PLoS ONE . Vol. 6, No. 11, 2011, e26964, doi : 10.1371 / journal.pone.0026964 .