Lituites
| Lituites | ||||||||||||
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Lituites littuus |
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| Temporal occurrence | ||||||||||||
| Lower Ordovician to Middle Ordovician | ||||||||||||
| approx. 488 to approx. 460 million years | ||||||||||||
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Lituites | ||||||||||||
| Bertrand , 1763 | ||||||||||||
Lituites (or bishop's staff ) is an extinct genus from the group of pearl boats i. w. S. It originated in the Lower Ordovician around 460 million years ago. It was first found in Scandinavia, later also in China, in the province of Hunan .
features
As with the ammonites, the casing of the genus Lituites is initially rolled up in a plane spiral. Later it grows straight or is only slightly curved. The part that is rolled up in a plane spiral and about half of the stretched part are chambered. The chambers are traversed by a thin extension of the posterior visceral sac ("siphonal cord") up to the first chamber. The remaining part of the housing ("living chamber") up to the mouth was not chambered; this part contained most of the animal's soft tissues, which could completely withdraw into the housing. The mouth of the adult animal had a pair of laterally ventrally attached protrusions ("lobes") and a pair of laterally dorsal protrusions. The exact function of these protrusions (or lobes) is unknown. The siphon line was located between the middle of the housing and the back (“subdorsal”). The surface has growth streaks, cross folds or cross ribs. On the sides between the dorsal and ventral protrusions, the growth strips trace a shallow, backward-curved bay ("lateral sinus"), and on the ventral side another bay ("funnel sinus"). The funnel was located in this shallow, rearward-facing bay in the mouth of the housing. The function of the side mouth bays is not known for sure. The case with the first part rolled up in a plane spiral and the later stretched part resemble a bishop's staff , hence the German name.
Systematics and nomenclature
The name Lituites was already established by Bruguière in 1765 without an assigned species. Later the species Orthocera lituus ( Modéer , 1795) was assigned to the genus Lituites , which became the type species of the genus according to the rules of zoological nomenclature. For a long time the name bishop's staff was then only applied to the type species Lituites lituus (Modeer, 1796), the holotype of which probably came from the island of Öland (Sweden). Further species were added to the genus Lituites later. The systematic position of the genus within the Nautiloidea i. w. S. was unsure for a long time. It was mostly placed in the order of the Tarphycerida , other authors assigned it to the order Barrandeocerida or the order Orthocerida . For some time, however, it has been placed in its own Lituitida order ( Starobogatow , 1974). In 1984 Jerzy Dzik again established a subordination Lituitina. The Lituitida order was then adopted by King (1999). Currently about 20 species are included in the genus Lituites . The better-known species are L. lituus , L. undatus , L. convolvans and L. angulatus .
literature
- Jerzy Dzik: Phylogeny of the Nautiloidea. In: Palaeontologia Polonica. Vol. 45, 1984, ZDB -ID 417871-3 , pp. 3-203.
- Andrew King: A review of Volchovian and Kundan (Arenig-Llanvirn) nautiloids from Sweden. In: Federico Olóriz, Francisco J. Rodríguez-Tovar (eds.): Advancing Research on Living and Fossil Cephalopods. Development and evolution. Form, construction, and function. Taphonomy, palaeoecology, palaeobiogeography, biostratigraphy, and basin analysis. Kluwer et al., New York NY et al. 1999, ISBN 0-306-45938-8 , pp. 137-159.
- Curt Teichert , Bernhard Kummel , Walter C. Sweet, HB Stenzel, William M. Furnish, Brian F. Glenister, Heinrich K. Erben , Raymond Cecil Moore , DEN Zeller (Eds.): Treatise on Invertebrate Paleontology. Part K: Mollusca. 3: Cephalopoda - General Features Endoceratoidea - Actinoceratoidea - Nautiloidea - Bactritoidea. Geological Society of America et al., New York NY et al. 1964, K1 – K519.
