Conulariids: fossilised jellyfish

Maria C Sendino and Paul D Taylor (UK) Fossils such as ammonites, trilobites, crinoids and shark’s teeth understandably attract the most attention from fossil enthusiasts. However, other groups can provide equally fascinating insights into the history of life and ought not to be neglected. Among these ‘Cinderella fossils’ are conulariids. Found in late Precambrian (Ediacaran) to Triassic marine deposits, conulariids survived for more than 350ma, disappearing about 200 million years ago, at a time when the continents were clustered together into a huge landmass called Pangaea. However, they are most common in Middle Ordovician to Permian rocks. Almost 400 species of conulariids have been described from around the world, and in some places they are abundant enough to lend their name to particular geological units, for example the Conularia-Sandstone in the Upper Ordovician of Jordan. Fig. 1. A species of Conularia from the Lower Carboniferous of Indiana showing the aperture closed by lappets. Affinities What are conulariids? Initially, they were thought to be molluscs because of their pyramidal-cone shape that is vaguely reminiscent of a straight nautiloid. Others believed them to be worm tubes. For a long time they were classified as ‘Problematica’, which is a formal way of admitting total ignorance about their affinities. They have also been placed in a phylum of their own, the Conulariida. This uncertainty results from the lack of preserved soft parts. However, strong evidence has emerged in recent years showing that conulariids belong to the same class – Scyphozoa – as jellyfish and … Read More