Seven species of shrimps referable to the Thalassinoidea and four species referable to the Paguroidea have been recovered from the Eocene Bateque and Tepetate formations of Baja California Sur, México. The large number of callianassid and paguroid taxa found in these essentially equivalent, very similar formations, is unusual in the decapod fossil record. Only a few other occurrences of such large numbers of fossil paguroid and thalassinoid taxa within a single unit are known; these occurrences range in age from Eocene to Miocene. Cuticular studies indicate that callianassid chelae were bioeroded, possibly by algae. An unusual occurrence of a hash of callianassid chelae may have sequence-stratigraphic value.