Following the Cretaceous extinction our knowledge of octopuses actually gets even worse. Evidence for octopuses consists of drill-holes in marine gastropods and these have been extensively studied. Despite the lack of an actual fossil of the creature in 1993 a name for the missing 'phantom' octopus was raised following extensive work on Miocene-period drill holes in European scallops, Oichnus ovalis. By 2002 at least seven separate Oichnus species have been identified differing from each other by minute variations in the borings. One Caribbean species, Oichnus excavatus has had its unique form of drill holes traced back to the Late Cretaceous in echinoids and probably thrived at least until the Middle Miocene. Such an animal that has been assigned a name for which we only have trace evidence and no body fossil is called a 'ichnogenus/ichnospecies