Ghost shrimps (Decapoda: Axiidea: Callianassidae) of the Maastrichtian (Late Cretaceous) Ocozocoautla Formation, Chiapas (Mexico)

摘要

On the basis of newly collected material, two ghost shrimp taxa from the lower Maastrichtian Ocozocoautla Formation in Chiapas (Mexico) are recorded. Callianassa burckhardti is reassigned to Eucalliax, which extends the known fossil record of this genus to the early Maastrichtian. A new species, Callianassa (s.l.) ocozocoautlaensis, is described based on a single specimen whose state of preservation does not enable a firm generic assignment, despite the fact that the material exhibits striking similarities to extant Callianassa modesta, occasionally treated as a member of the genus Cheramus. The fossil record of ghost shrimps from Mexico is briefly reappraised and their survival across the K/Pg boundary is discussed. The conservative body plan of ctenochelid and callianassid taxa is emphasized and it is postulated that virtually all major ghost shrimp clades were already established well before the Cenozoic.