The urostyle is the name given to a modified bony structure, originally the end of the notochord, turned upward in most fishes.
The urostyle is post-sacral and corresponds to three or more modified vertebrae.
The post-sacral part of the spinal column ossifies continuously, forming an unsegmented cylindrical rod, the urostyle.
In Anura the number of vertebrae is very greatly reduced, only nine and the urostyle being present.
The ultimate changes of the notochord and urostyle vary very considerably in the different types of Teleostei.
The urostyle is a long rod-like bone forming the posterior unsegmented continuation of the vertebral column.
The urostyle is a long cylindrical rod which articulates with the sacrum generally by two facets.