Tessellation was earlier considered for Direct3D 10, but was later abandoned. GPUs such as Radeon R600 feature a tessellation engine that can be used with Direct3D 9/10/10.1 and OpenGL, but it's not compatible with Direct3D 11 (according to Microsoft). Older graphics hardware such as Radeon 8xxx, GeForce 3/4 had support for another form of tesselation (RT patches, N patches) but those technologies never saw substantial use. As such, their support was dropped from newer hardware.
Tessellation was earlier considered for Direct3D 10 but was later abandoned GPUs such as Radeon R600 feature a tessellation engine that can be used with Direct3D 9/10/101 and OpenGL but it's not compatible with Direct3D 11 (according to Microsoft) Older graphics hardware such as Radeon 8xxx GeForce 3/4 had support for another form of tesselation (RT patches N patches) but those technologies never saw substantial use As such their support was dropped from newer hardware