The spiny murex are some of the most spectacular marine snails. This fine example of Chicoreus ramosus contains many of the structural and ornamental attributes that are common to many other species. The spectacle of most murex shells lies in their ornamentation – arrays of spines, nodes, and spiral threads that extend around whorl circumferences. Many of these calcareous growths form at the intersections with growth lines – the growth lines in most gastropods extend the length of the shell (and not its circumference).

The morphology of common invertebrates – for sedimentologists

Ok, you’re not a paleontologist but during a sedimentological – stratigraphical examination of outcrop or core you encounter body and trace fossils – whole and fragmented shells, carapaces, skeletons, or rigid frameworks, as scattered occurrences, or packed communities. Notwithstanding their potential biostratigraphic value, identification of these fossil critters will provide important clues about depositional processes and paleoenvironments, paleoecology, unconformities and condensed sections, and taphonomy (how dead critters are preserved). The circumstances of field work may mean that your eager paleontologist colleague cannot stand at the outcrop and regale you with all the observable taxonomic and paleoecological information you need. That task is appointed to you.

Identifying fragments even to the level of phylum is a useful beginning; are they molluscs or brachiopods, corals or bryozoa. It is a truism that the larger or more complete a fossil, the easier it will be to identify to any taxonomic level. However, even with small fragments there may be distinguishing features that allow identification to Class or Order levels of taxonomy. For example, it will frequently be possible to determine whether fragments of molluscs are bivalves (pelecypods), gastropods, or ammonites?

The posts herein provide brief descriptions of the morphological attributes of the more commonly fossil invertebrates.

Here also is a glossary of the terms used in these posts – Glossary of Paleontology

Bivalve morphology for sedimentologists

Trilobite morphology for sedimentologists

Gastropod shell morphology for sedimentologists

Cephalopod morphology for sedimentologists

Brachiopod morphology for sedimentologists

Echinoderm morphology for sedimentologists

Coral morphology for sedimentologists

Graptolite morphology for sedimentologists