Lituites

Lituites littuus

• Asia
• Europe

Lituites (or crozier ) is an extinct genus of the group of Nautiluses iwS It originated in the Lower Ordovician around 460 million years ago. It was first found in Scandinavia, and later in China, in the province of Hunan.

Features

The housing of the genus Lituites is rolled initially planispiral as the ammonites. Later, it grows straight or only slightly curved. Planispiral the rolled portion, and about half of the straight portion are chambered. The chambers are of a thin extension of the posterior visceral sac ( " Siphonalstrang " ) crossed to the first chamber. The remainder of the housing ( " living chamber " ) to the mouth was ungekammert, in this part, there was the largest part of the soft parts of the animal, which was able to completely retract into the housing. The mouth of the adult animal had a pair of laterally -faceted ventral projections ( " rag " ) and a pair of laterally -faceted dorsal projections. The exact function of these projections ( or cloth ) is unknown. The Siphonalstrang was between the center of the housing and the back side ( " subdorsal "). The surface shows growth lines, transverse folds or transverse ribs. The growth lines are characterized by the sides between the dorsal and ventral projections each have a shallow bay bent backwards ( " Lateralsinus ") and on the ventral side, a further rear facing bay ( "funnel sine " ) to. In this shallow, rear-facing bay at the mouth of the case there was the funnel. The function of the lateral estuaries is not known for sure. The housing with the planispiral rolled first part and the later part stretched resemble a bishop's staff, hence the German name.

Systematics and Nomenclature

The name Lituites was already established by Brugière in 1765 without an assigned type. Then the genus Lituites Later the kind Orthocera lituus Modeer, assigned in 1795, the so according to the rules of zoological nomenclature, the type species of the genus was. The name of crozier was then used for a long time only to the type species Lituites lituus ( Modeer, 1796), the holotype probably from the island of Öland (Sweden ) came. Later, other species have been assigned to the genus Lituites. The systematic position of the genus within the Nautiloidea iwS has long been uncertain. It was usually made ​​to the order of Tarphycerida, other authors, they showed the order Barrandeocerida to or to the order Orthocerida. For some time, however, it is placed in its own order Lituitida Starobogatov, 1974. Jerzy Dzik 1984 again established a subordination Lituitina. The order Lituitida was then taken over by King ( 1999). At present, about 20 species are assigned to the genus Lituites. The better-known species are L. lituus, L. undatus, L. convolvans and L. angulatus.