Sclerotic ring

The scleral ring (also Sklerotalring, Greek σκληρός skleros "hard", Latin annulus ossicularis sclerae ) is a ring-shaped, bony reinforcement of the eye of birds, the extinct dinosaurs, pterosaurs and ichthyosaurs, but also some modern reptiles such as iguanas. It is composed on average of 14-15 bone plate annularly embedded in the sclera in the transition to the cornea. They are arranged to overlap and can be completely melted.

The scleral ring is located directly behind the iris visible from the outside, but before the lens. He usually has no contact with other bones. The visible iris is rooted to the outer side of Skleralringes suspended on the inside of the lens thereto. Because the iris is rooted in the scleral ring, the diameter of the pupil never be larger than the center hole of Skleralrings. This allows for a precise statement of the maximum pupil size of the species in the reconstruction of extinct species. Formed flat the scleral ring among other things for hen birds and songbirds, on the other hand he is tubular eg when the owls, whereby their elongated eyes have a higher focal length and thus greater vision in the dark. The scleral ring supports the eyeball and gives the Akkomodationsapparat a starting point.

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