Teleost fish apparently have a similar arrangement, although the numbers of elements vary. Sharks have a different gene arrangement, with hundreds of separate gene clusters, each consisting of a V, two Ds, a J and a six-exon C region. Another unique feature of shark immunoglobulin genes is that about half the genes are joined in the germ line instead of somatically. A third unique feature is the absence of the regulatory octamer which is found associated with the B cell-specific immunoglobulin promoter in teleosts and tetrapods. In the coelacanth, C and J regions are lacking, and V regions may be tandemly linked and may or may not be associated with a single D region.
Birds have a third pattern of gene arrangement.
The diversity of immunoglobulin gene arrangements suggests separate design in their creation. These fossils resemble Precambrian Ediacaran fossils, which have usually been found separated from Cambrian fossils. This unusual combination is interpreted as indicating that the Ediacaran fauna is not phylogenetically isolated from the Cambrian fossils. Gingerich PD, Raza SM, Arif M, Anwar M, Zhou X. 1994. New whale from the Eocene of Pakistan and the origin of cetacean swimming.