Lituitidae
From Wikipedia, the free encyclopedia
| Lituitidae | |
|---|---|
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Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Cephalopoda |
| Subclass: | Nautiloidea |
| Order: | †Tarphycerida |
| Family: | †Lituitidae |
The Lituitidae are a family of evolved tarphycerids characterized by a long orthoconic section that follows a coiled juvenile portion at the apex, along with a generally tubular siphuncle, which like that of the barrandeocerids is composed of thin connecting rings.
Flower and Kummel (1950)[1] included the Lituitidae in the Barranderocerida which are now included in the Tarphycerida as a number of derived families. Furnish and Glenister (1964)[2] removed the Lituitidae to the Tarphycerida on the basis of observed similarities in the structure of the siphuncle. Other taxonomies, e.g. Dzik (1981)[3] include the Lituitidae in the Orthocerida partly on the basis of the subcentral siphuncle and thin connecting rings, on the misconception that Rhynchorthoceras is ancestral.
Classification
The Lituitidae comprise two basic groups, based on general form. One is represented by Ancistroceras and Holmiceras and probably includes Angelinoceras. The other is represented by Litoceras, which first appears later in the early Middle Ordovician.[2]