Asteroid (Echinodermata) skeletal elements from upper Oligocene deposits of Jamaica and Antigua

Abstract

AbstractThe Antillean Cenozoic fossil record of asteroids comprises mainly dissociated ossicles. Most common among isolates from upper Oligocene deposits of Jamaica and Antigua are marginal ossicles of an extinct, indeterminate species ofPycinaster. This is the youngest known occurrence of the genus and the first from beyond Europe. A number of relatively complete fossils have been assigned toPycinasterand (sub)familial status proposed for it together withPhocidaster. The latter proposition is based solely on a few marginals, but available diagnoses are judged insufficient to justify such recognition. The taxon Pycinasteridae is here synonymized with the Goniasteridae, although future study of added features (such as the ventral surface) might justify recognition at a higher taxonomic level. In addition to ossicles assigned toPycinaster, many marginals are tentatively assigned to the surviving goniasteridNymphaster. Numerous generic and many species names have been based on asteroid isolates, but the practice demands assumptions that are not readily justified. Linkage of discrete isolates under a single taxon name assumes derivation from a single source, an inference that can be verified only rarely (if ever), therefore reducing names to the single holotype ossicle. Availability of only isolates encourages comparison with extant taxa and biogeography, biasing interpretations with a Holocene overlay. Because of these constraints, a new nominal species ofPycinasteris not justified and assignment of ossicles toNymphasteris tentative. However, given the importance of asteroids in marine communities, we emphasize the significance, largely ignored, of their presence in Cenozoic deposits of the wider Caribbean.