A broad study of the Conulariida reveals many unresolved issues regarding their palaeobiology and systematics. Evidence previously cited in support of a scyphozoan affinity is found to be inconclusive; suggested close affinities with other groups such as annelids and molluscs are also rejected. It seems preferable to consider conulariids as an extinct group of phylum status. The structure and composition of the conulariid shell is investigated and discussed in a functional context. The phosphatic conulariid shell is usually thin (possibly because of the environmental scarcity of phosphate) with a large organic component (probably from biomechanical constraint). A mantle-type secretory regime for the conulariid shell is proposed. This and various microstructural features of the shell seem to argue against a cnidarin affinity. The conulariid shell has features in common with the skeletons of brachiopods, molluscs and conodonts although a close affinity with any of these groups is probably unlikely. Patterns of conulariid distribution and abundance are analysed. A recurrent theme appears to be the occurrence of abundant conulariids in unusual sedimentary settings associated with low diversity benthic faunas. A pelagic mode of life for some conulariids remains a possibility although a benthic, upright, sessile lifestyle for the majority of conulariid taxa seems most likely. The apical diaphragm is not interpreted in terms of a mode of life transition but as a taphonomic feature resulting from an originally fragile septate shell. A systematic revision of the Conulariida allows a tentative phylogeny to be proposed together with a new classification. The Conulata, comprising the single order Conulariida, are elevated to phylum status, <i>Stenothecopsis</i> and <i>Glyptoconularia</i> are given subfamilial status, with <i>Conchopeltis</i> and <i>Sphenothallus</i> removed from the Conulata. The following new taxa are described; <i>Exoconularia</i> sp. nov. a., <i>Pseudoconularia</i> sp. nov. a. and <i>Paraconularia crustula</i> var. nov. a.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:638261 |
| Date | January 1986 |
| Creators | Mortin, J. |
| Publisher | Swansea University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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