Sclerotic ring

Sclerotic rings are rings of bone found in the eyes of many animals in several groups of vertebrates, except for extant mammals and crocodilians.[2] They can be made up of single bones or multiple segments[3] and take their name from the sclera. They are believed to have a role in supporting the eye, especially in animals whose eyes are not spherical, or which live underwater.[2] Fossil sclerotic rings are known for a variety of extinct animals, including ichthyosaurs, pterosaurs, and dinosaurs,[4] but are often not preserved.

Diagram showing the position of the sclerotic ring within a bird eye
A skull of a Uroplatus (leaf-tailed gecko), showing large sclerotic rings
The sclerotic ring of Ophthalmosaurus ("eye lizard") was one of the largest in the animal kingdom[1]

References
  1. Milner, Angela. "Ophthalmosaurus icenicus: Why did it have such large eyes?". Natural History Museum, London. Retrieved 15 October 2013.
  2. Motani, Ryosuke (15 November 2001). "Eyes of Ichthyosaurs". UC Museum of Paleontology. Retrieved 15 October 2013.
  3. "Palaeos Vertebrates: Glossary S". Retrieved 2007-07-06.
  4. Pigdon, Dann. "Re: Sclerotic ring in eyes". Retrieved 2007-07-06.


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