Polymorphism in Silurian Chitinozoans from Tunisia

Polymorphism of chitinozoans has been known to exist for almost a decade. A review of published literature shows an extreme rarity of illustrations of this phenomenon. However, polymorphism may not be all that rare, although its occurrence may show regional biases. Polymorphism has been found to occur in frequencies of 0.1 to 0.01 percent of certain Silurian angochitinids and desmochitinids (Linochitina spp.), but not of conochitinids or cyathochitinids, in the Silurian paleo-high-latitudinal sand/mudstone area, nor at North Africa. It is much rarer in the Silurian paleo-equatorial belt.