Cruziana acacensis Seilacher - New interpretation of origin

Cruziana acacensis Seilacher - Nova interpretacija nastanka

Abstract

An external cast from the Silurian Acacus Formation of Jabal Acacaus in Fazzan (locality of the Desio's collection, 1940; Libya) shows herringbone-shaped bands on bilobate base. This is typical Cruziana acacensis Seilacher. Fossil shows, however, new surprising details: mouth cast on the ventral surface, seven nodes on each side where external banded gills end, eye casts, nasal capsule apertures and posterior apertures of the general gill canals. This fossil was formed as an external cast from the external mould of an unknown and extinct Agnatha group with the presence of characteristic external banded gills. New fact of the Cruziana acacensis origin lead to the news and important inferences.