Mandibles

Last week, Nature (vol. 544, page 417) reported on a fossilised creature with huge pincers resembling can-openers, a hinged two-piece shell and more than 50 pairs of legs.  C. Aria and J-B. Caron call this Tokummia katalepsis and argue that its evolution led to insects, crustaceans, millipedes and centipedes. They are among the few fossils that show early links between these familiar groups.

The creature lived about 507 million years ago during the Cambrian period, It was about 10cm long and would have been found walking on the seafloor.

The creature was about 10cm long and would have been found walking on the seafloor.
 Photograph: Jean-Bernard Caron. Copyright: Royal Ontario Museum

Prey would have been caught by the animal using its two large pincers. It would then have been passed to the animal’s many legs under the body which have spine-like features at their base which may have crushed the prey. This could then have been brought back to the mandibles and be cut into small pieces to help digestion.

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Photograph: Lars Fields. Copyright: Royal Ontario Museum

This is an artist’s reconstruction of Tokummia katalepsis showing a pair of large pincers to capture prey, with much of the multisegmented body protected by a broad carapace. The small mandibles and subdivided, spine-like bases of the legs were critical characters for resolving the evolutionary significance of Tokummia.