Is easy to identify them as that, but Arachnids and antennas are incompatible and Chelicerata (like horseshoe crabs) is the only group bearing chelicera. Crusta

Is easy to identify them as that, but Arachnids and antennas are incompatible and Chelicerata (like horseshoe crabs) is the only group bearing chelicera. Crustaceans have two pairs of antennas and different shaped legs. Insects are (almost) non marine (a few notorious exceptions). Millipedes were never found on the sea and the head appendix were placed in different segments. But the new info about the mouth parts is extraordinary and could still lead to big discoveries and earthquakes in taxonomy. The problem with this animals is that all the mouth pieces that fossilized were from different types or in different positions compared with all arthropods alive or extinct that were not trilobites.