Straying from a proper course or standard
Departing from the normal
In the Malacostraca, an elongated heart with numerous segmentally arranged ostia is found only in the aberrant group of Stomatopoda and in the transitional Phyllocarida.
They are not tales of aberrant individuals but of societal norms.
Platygonus is an aberrant type which died out in the Pleistocene.