Lechritrochoceratidae
Encyclopedia
Lechritrochoceratidae is a family of derived tarphycerids
from the middle and upper Silurian, once included in the now largely abandoned Barrandeocerida, which comprise dextrally torticonic genera with costate shells and ventrally displaced siphuncles. Offset coiling in low spired. Rate of expansion and coarseness of costae vary, genus to genus. Costae are generally narrow and sharp with wide areas between and slant dorso-ventrally toward the apex. Six genera have been described:
Tarphycerida
The Tarphycerida were the first of the coiled cephalopods. They are found in marine sediments from the Lower Ordovician to the Middle Devonian. Some like Aphetoceras and Estonioceras are loosely coiled, gyroconic, others like Campbelloceras, Tarphyceras, and Trocholites are tightly coiled, but...
from the middle and upper Silurian, once included in the now largely abandoned Barrandeocerida, which comprise dextrally torticonic genera with costate shells and ventrally displaced siphuncles. Offset coiling in low spired. Rate of expansion and coarseness of costae vary, genus to genus. Costae are generally narrow and sharp with wide areas between and slant dorso-ventrally toward the apex. Six genera have been described:
- Lechritrochoceras
- Catyrephoceras
- Leurotrochoceras
- Peismoceras
- Systrophoceras
- Trochodicyoceras
References
- Sweet, Walter C. 1964. Nautiloidea -Barrandeocerida. Treatise on Invertebrate Paleontology, Part K. Geological Soc. of America and Univ of Kansas press.
- Lechritrochoceratidae -Paleodb