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Sclerotic rings are rings of bone found in the
File:Tawny Frogmouth Skull.jpg, A skull of an extant tawny frogmouth, showing large sclerotic rings.
File:Uroplatus_phantasticus_skull1.jpg, A skull of an extant satanic leaf-tailed gecko, showing large sclerotic rings.
File:Viatkogorgon skull.png, Skull and sclerotic ring of the gorgonopsian '' Viatkogorgon''.
File:Prosaurolophus maximus3.JPG, Sclerotic ring of the hadrosaur '' Prosaurolophus''.
Sclerotic rings are rings of bone found in the eye
Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and conv ...
s of many animals in several groups of vertebrates, except for mammal
Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...
s and crocodilians. They can be made up of single bones or multiple segments and take their name from the sclera
The sclera, also known as the white of the eye or, in older literature, as the tunica albuginea oculi, is the opaque, fibrous, protective, outer layer of the human eye containing mainly collagen and some crucial elastic fiber. In humans, and som ...
. They are believed to have a role in supporting the eye, especially in animals whose eyes are not spherical, or which live underwater. Fossil sclerotic rings are known for a variety of extinct
Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...
animals, including ichthyosaur
Ichthyosaurs (Ancient Greek for "fish lizard" – and ) are large extinct marine reptiles. Ichthyosaurs belong to the order known as Ichthyosauria or Ichthyopterygia ('fish flippers' – a designation introduced by Sir Richard Owen in 1842, altho ...
s, pterosaurs, and dinosaurs, but are often not preserved.
References
Vertebrate anatomy Dinosaur anatomy Eye Skull {{vertebrate-anatomy-stub