''Ceolodiscus'' is a genus in the gastropod family

Euomphalidae Euomphalidae is an extinct family of Paleozoic to early Mesozoic marine molluscs which may be gastropods with anisostrophically coiled shells (according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005). The shells show a selenizone ...

from the Lower and Middle

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The J ...

of Europe. The shell is small but stocky; involute or with a slightly protruding spire. Whorls are generally smooth, evenly rounded and slightly overlapping; umbilicus deep, aperture ovate.Teichert, S., & Nützel, A. (2015). Early Jurassic anoxia triggered the evolution of the oldest holoplanktonic gastropod Coelodiscus minutus by means of heterochrony. ''Acta Palaeontologica Polonica'', 60(2), 269–276. Is the oldest known holoplanktonic gastropod, thanks to a bilateral symmetrical shells as an adaption to active swimming. Also the most common of the sea snails of the Posidonienschiefer Formation, it is also one of the most varied in size terms, with some of the biggest specimens of snail from the Lower Toarcian know. It has been related to large floating driftwood as one of the primary settlers.

References

*Teichert, S., & Nützel, A. (2015). Early Jurassic anoxia triggered the evolution of the oldest holoplanktonic gastropod Coelodiscus minutus by means of heterochrony. ''Acta Palaeontologica Polonica'', 60(2), 269–276. *J. B. Knight ''et al''. 1960. Systematic descriptions; Treatise on Invertebrate Paleontology, Part I, Mollusca (1):''I''196.
Coelodiscus
Gastropod genera Euomphalidae Jurassic gastropods Jurassic animals of Europe Fossil taxa described in 1909 {{Paleo-gastropod-stub