Stenopelix

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Stenopelix
The holotype of Stenopelix from the Obernkirchen sandstone

The holotype of Stenopelix from the Obernkirchen sandstone

Temporal occurrence
Lower Cretaceous (late Berriasian )
141.9 to 139.3 million years
Locations
Systematics
Dinosaur (dinosauria)
Pelvic dinosaur (Ornithischia)
Cerapoda?
Marginocephalia?
Pachycephalosauria?
Stenopelix
Scientific name
Stenopelix
Meyer , 1857

Stenopelix (translated "narrow basin") is a genus of bird pelvic dinosaurs (Ornithischia)known only from sparse finds, possibly from the group of Pachycephalosauria or Ceratopsia . The only known species is S. valdensis (the surname denotes the formation, the Wealden ).

From stenopelix has so far been only one copy, and found for this only parts of the fuselage skeleton. The skull , which would undoubtedly allow an exact systematization, is not known.

Stenopelix was relatively small at around 1.5 to 2 m in length. In the only specimen found - which came from an almost fully grown animal - the preserved part of the spine is 97 cm long and the tail 55 cm, the neck missing. He walked biped on his hind legs. It is often reconstructed based on psittacosaurs or pachycephalosaurs.

The fossil remains of Stenopelix were found in 1855 near Obernkirchen in Lower Saxony , known for its construction sandstone. The site was the sandstone quarries of the Harrl , a western foothill of the Bückeberg , in which crocodile fossils (and turtle shells) had been found shortly before and later dinosaur tracks.

In 1857 Stenopelix was first described by the Frankfurt paleontologist Hermann von Meyer (1801-1869).

The classification as a dinosaur was carried out by Ernst Koken in 1887. His fossils are dated in the Lower Cretaceous (late Berriasian ) to an age of 142 to 139 million years. At that time there were swamps of a large estuary in the Lower Chalk Sea to the north, which also left coal deposits behind.

Systematics

The systematic classification of Stenopelix has been controversial since it was first described.

By Franz Baron von Nopcsa he was placed in a separate family (Stenopelyxidae) in 1917 and 1923 the hypsilophodont assigned (Gazelle dinosaurs). Alfred Romer classified them in 1946 in the vicinity of the psittacosaurs.

In a re-examination of the skeleton by Hermann Schmidt (Münster) in the 1960s, Stenopelix could clearly be assigned to the ornithischia, based on the discovery of the postpubis elongation of the pubic bone, a typical feature of the ornithischia.

In the 1970s, Teresa Maryanska and Halszka Osmolska found similarities between the Stenopelix skeleton and pachycephalosaurs (thick-headed skull dinosaurs) newly found by Polish expeditions in Mongolia. Examples of the similarities were according to these authors: the construction of the basin had the pubic bone (pubis) no part in the acetabulum (but was belying of Suez and Galton) (acetabulum) and the strong caudal fin (the Suez and Galton then as sacral ribs identified).

The pachycephalosaurs are known from the Lower Cretaceous (around 125 million years) of the Isle of Wight, except for Yaverlandia , only from the Upper Cretaceous in East Asia and North America. Peter Galton (the first describer of Yaverlandia) therefore classified Yaverlandia and Stenopelix in the same genus in 1976 .

After a re-examination of the fossils with Hans-Dieter Sues in 1982, however, both saw one of the oldest known ancestors of the ceratopsian in Stenopelix . Because of its size, it is most comparable to the psittacosaurs. In contrast to the Psittacosauridae (and Protoceratopsidae), the thigh (femur) of Stenopelix was longer than the shinbone (tibia), but the pelvis was similar: short process on prepubis, posterior process on pubis short, missing obturator process (otherwise known as a Key feature of ornithischia applies). It is possible that it can also be classified in the vicinity of common ancestors of the pachycephalosaurs and ceratopsians, both of which are now regarded as related and are grouped together as the Marginocephalia .

Other scientists such as Robert Sullivan consider the findings to be too sparse for a systematic classification and list it as "Ornithischia incertae sedis ".

The specimen was in the collection of Max Ballerstedt (1857-1945), the nestor of dinosaur tracking research in the Bückeberge, in the Adolfinum Bückeburg high school and came in the 1970s to the Geological-Paleontological Institute of the University of Göttingen, where in 2008 Geological Museum also a replica was put up.

literature

  • Teresa Maryańska , Ralph E. Chapman, David B. Weishampel : Pachycephalosauria. 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. 464-477.
  • Ernst Probst , Raymund Windolf: Dinosaurs in Germany. Bertelsmann, Munich 1993, ISBN 3-570-02314-1 , pp. 211-217 (illustration of the skeleton found on p. 212, reconstruction p. 219).
  • Hermann Schmidt: Stenopelix valdensis H. v. Meyer, the little dinosaur from Wealden in northern Germany. In: Paleontological Journal . Vol. 43, No. 3/4, 1969, pp. 194-198, doi : 10.1007 / BF02987651 .
  • Hans-Dieter Sues , Peter Galton : The systematic position of Stenopelix valdensis (Reptilia: Ornithischia) from the Wealden of north-western Germany. In: Palaeontographica. Department A: Paleozoology, Stratigraphy. Vol. 178, No. 4/6, 1982, ISSN  0375-0442 , pp. 183-190.
  • Robert M. Sullivan: A taxonomic review of the Pachycephalosauridae (Dinosauria: Ornithischia). In: Spencer G. Lucas, Robert M. Sullivan (Eds.): Late Cretaceous Vertebrates from the Western Interior (= New Mexico Museum of Natural History and Science. Bulletin. 35, ISSN  1524-4156 ). New Mexico Museum of Natural History and Science, Albuquerque NM 2006, pp. 347–365, digital version (PDF; 4.79 MB) .

Web links

Individual evidence

  1. ↑ Jahn J. Hornung, Annina Böhme, Torsten van der Lubbe, Mike Reich, Annette Richter: Vertebrate tracksites in the Obernkirchen Sandstone (late Berriasian, Early Cretaceous) of northwest Germany - their stratigraphical, palaeogeographical, palaeoecological, and historical context. In: Paleontological Journal . Vol. 86, No. 3, 2012, pp. 231-267, doi : 10.1007 / s12542-012-0131-7 .
  2. ↑ However, mining had been inactive there since the 1860s.
  3. ↑ Hermann von Meyer : Contributions to the closer knowledge of fossil reptiles. In: New yearbook for mineralogy, geognosy, geology and petrefacts. Jg. 1857, pp. 532-543, ZDB -ID 123936-3 , digitized ; Hermann von Meyer: Stenopelix valdensis, a reptile from the Walden formation in Germany. In: Palaeontographica. Vol. 7, Delivery 1, 1859, ZDB -ID 207560-x , pp. 25-34, digitized .
  4. ^ Teresa Maryańska , Halszka Osmólska : Pachycephalosauria, a new suborder of ornithischian dinosaurs. In: Palaeontologia Polonica. Vol. 30, 1974, ISSN  0078-8562 , pp. 45-102, digital version (PDF; 5.67 MB) .
  5. ^ Robert M. Sullivan: A taxonomic review of the Pachycephalosauridae (Dinosauria: Ornithischia). In: Spencer G. Lucas, Robert M. Sullivan (Eds.): Late Cretaceous Vertebrates from the Western Interior (= New Mexico Museum of Natural History and Science. Bulletin. 35, ISSN  1524-4156 ). New Mexico Museum of Natural History and Science, Albuquerque NM 2006, pp. 347-365.
  6. ↑ And a controversial assignment of Ferganocephale from the Central Jura of Kyrgyzstan, of which only teeth are known.
  7. ↑ cf. also Robert L. Carroll : Paleontology and Evolution of the Vertebrates. Thieme, Stuttgart et al. 1993, ISBN 3-13-774401-6 , p. 324.
  8. ^ Robert L. Carroll: Paleontology and Evolution of the Vertebrates. Thieme, Stuttgart et al. 1993, appendix, classifies it as “Ceratopsia incertae sedis” according to Galton / Sues.