Betty and Ag: My understanding of sclerotic ossicles in reptiles and birds (and presumably dinosaurs ) is as follows. As has been mentioned, accomodation is the ability of the lens to change shape based on how close the viewing object is to the eye, thus focusing the rays of the light better on the retina. Ciliary muscles attach to the lens and to the wall of the eyeball (sclera), and contract and relax to produce change in the lens shape. Reptiles and birds have the finest visual acuity and accomodation of all vetebrates, and the eyes are large, especially in birds. The sclera is stiffened by a cartilaginous cup behind and by a ring of small bones (ossicles) on the foreward wall, where the eyeball might be otherwise distorted by the ciliary muscles. These muscles are striated and fast in action, as opposed to mammals which have smooth ciliary muscles and are relatively slow to work. --Ken Clay, M.D.... in discribing the function of sclerotic ossicles, Colbert says
they ...have "a function in the mechanism of accomodation". What's that?Accommodation is the movement or shape-shifting of the lens or diotropic
apparatus to maintain or change focus of the image. It is possible that
the sclerotic ossicles acted in some way to manipiulate the lens or the
eyeball so that light was focused on the retina and it could be retained inAg