''Rotularia'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

planispiral Planispiral is a condition in which a tubicolous shell is coiled in a single horizontal plane and the diameter increases away from the axis of coiling. This term is usually used for describing gastropod shells. Many cephalopods and tubeworm A tu ...

ly coiled fossil

polychaete worms Polychaeta () is a paraphyletic class of generally marine annelid worms, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are ma ...

in the family

Serpulidae The Serpulidae are a family of sessile, tube-building annelid worms in the class Polychaeta. The members of this family differ from other sabellid tube worms in that they have a specialized operculum that blocks the entrance of their tubes whe ...

. Owing to the gastropod-like shape of ''Rotularia'', many authors in the past interpreted this genus as being sea snails in the family

Vermetidae The Vermetidae, the worm snails or worm shells, are a taxonomic family of small to medium-sized sea snails, marine gastropod molluscs in the clade Littorinimorpha. The shells of species in the family Vermetidae are extremely irregular, and ...

. All ''Rotularia'' species were cemented to the substrate during their earliest growth stage, but they became detached shortly after the formation of the first whorls (Savazzi, 1995). Their tubes have two layers with different microstructure (Vinn, 2008). This genus is known from the early

Kimmeridgian In the geologic timescale, the Kimmeridgian is an age in the Late Jurassic Epoch and a stage in the Upper Jurassic Series. It spans the time between 157.3 ± 1.0 Ma and 152.1 ± 0.9 Ma (million years ago). The Kimmeridgian follows the Oxford ...

to Late

Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', " ...

(Jäger, 2004).

References

*Jäger, M. 2004. Serpulidae und Spirorbidae (Polychaeta sedentaria) aus Campan und Maastricht von Norddeutschland, den Niederlanden, Belgien und angrenzenden Gebieten. Geologisches Jahrbuch (A) 157, 121–249. *Savazzi, E. 1995. Morphology and mode of life of the polychaete ''Rotularia''. Paläontologische Zeitschrift 69, 73–85. * Serpulidae Prehistoric annelid genera Kimmeridgian genus first appearances Eocene genus extinctions Late Jurassic invertebrates Late Cretaceous invertebrates Paleocene invertebrates Eocene invertebrates Fossil taxa described in 1827 Early Cretaceous invertebrates {{annelid-stub