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There are no known fossils of aplacophorans. Some fossils have been attributed to Aplacophora, but
these placements are as yet uncertain. The only hard parts of aplacophorans, the spicules, quickly
become disassociated after the death of the animal. Thus there is little shape preserved from a living
aplacophoran.
However, as you can see from the phylogeny, both groups of Aplacophora (shown in red) are basal members of Mollusca. Since many fossils have been found from as far back as the Cambrian (over 540 million years ago) of other groups of mollusks, it is certain that Aplacophora also existed since this time. Perhaps it is just a matter of time before a fossil can be confidently determined to be a member of Aplacophora. |
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