Zygosphene-Zygantrum Joint

The zygosphene-zygantrum joint is an additional joint between the vertebrae that occurs in various reptiles belonging to the group of Lepidosauromorpha . This pivot joint is formed by a forward-facing wedge-like extension, the zygosphene , which fits into a rear depression of the preceding vertebra, the zygantrum . The zygosphene is located between the prezygapophyses on the front of the vertebral arch , while the zygantrum sits between the postzygapophyses on the back of the vertebral arch.

This joint occurs in snakes , Real lizards , teiidae , gymnophthalmidae and some iguanas and belt tails on. It is also less pronounced in the bridge lizards. It can also be found in some purely fossil groups such as the plesiosaurs , the nothosaurs and the pachypleurosaurs . It is missing in today's monitor lizards , but was present in fossil representatives of this group.

The zygosphene-zygantrum joint is used to stabilize the spine. It allows horizontal and vertical movements of the spine, but prevents the individual vertebrae from twisting against each other.

supporting documents

↑ Gunde Rieger, Wilfried Westheide: Special Zoology. Part 2: vertebrates or skulls . Springer, 2009, ISBN 978-3-8274-2039-8 , pp. 381 .
↑ Jack M. Callaway, Elizabeth L. Nicholls: Ancient Marine Reptiles . Academic Press, 1997, ISBN 0-08-052721-3 , pp. 125 .
^ Richard Estes, Kevin de Queiroz, Jacques Gauthier: Phylogenetic Relationships within Squamata . In: Richard J. Estes (Ed.): Phylogenetic Relationships of the Lizard Families: Essays Commemorating Charles L. Camp . Stanford University Press, 1988, ISBN 0-8047-1435-5 , pp. 166 .
↑ Michael J. Benton: Vertebrate palaeontology . 3. Edition. Blackwell Science, 2005, ISBN 0-632-05637-1 , pp. 150 .
^ ^A ^b Alfred Sherwood Romer: Osteology of the Reptiles . The University of Chicago Press, Chicago / London 1956, ISBN 0-226-72487-5 , pp. 256 .

[rieger2009-1] Gunde Rieger, Wilfried Westheide: Special Zoology. Part 2: vertebrates or skulls . Springer, 2009, ISBN 978-3-8274-2039-8 , pp. 381 .

[callaway1997-2] Jack M. Callaway, Elizabeth L. Nicholls: Ancient Marine Reptiles . Academic Press, 1997, ISBN 0-08-052721-3 , pp. 125 .

[estes1998-3] Richard Estes, Kevin de Queiroz, Jacques Gauthier: Phylogenetic Relationships within Squamata . In: Richard J. Estes (Ed.): Phylogenetic Relationships of the Lizard Families: Essays Commemorating Charles L. Camp . Stanford University Press, 1988, ISBN 0-8047-1435-5 , pp. 166 .

[benton2005-4] Michael J. Benton: Vertebrate palaeontology . 3. Edition. Blackwell Science, 2005, ISBN 0-632-05637-1 , pp. 150 .

[romer1956-5] A ^b Alfred Sherwood Romer: Osteology of the Reptiles . The University of Chicago Press, Chicago / London 1956, ISBN 0-226-72487-5 , pp. 256 .