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In the absence of lanterns and spines, the identification of fossil diadematids is extremely difficult. This is because we now know that species traditionally assigned to the Pseudodiadematidae can have test morphologies similar to diadematids but possess keeled teeth and solid spines. The oldest true diadematid that can be currently recognized is late Cretaceous. However, it is fairly certain that the group has a longer history than this and that when some Jurassic regular echinoids become better known they will turn out to belong this family. |