Paper No. 135-4
Presentation Time: 9:45 AM
ONTOGENY, INTER- AND INTRASPECIFIC VARIATION, PALEOBIOGEOGRAPHY, TAPHONOMY, AND SYSTEMATICS OF THE CENOZOIC GHOST SHRIMP GLYPTURUS
Studies in systematic paleontology are greatly aided when numerous, well-preserved specimens are available, so that quantitative methods can be used to substantiate qualitative observations. This is often not the case for fossil decapod crustaceans due to their relatively low preservation potential. Here, we examined two large collections of the well-preserved fossil ghost shrimp Glypturus, from the Holo-Pleistocene of Panama and the late Miocene of Florida (USA). Using descriptive, bivariate, multivariate, and geometric morphometric methods, two new species are described based on appendage material: Glypturus n. sp. 1 and G. n. sp. 2. New characters are identified, and ontogenetic and intraspecific variation is assessed for these taxa and modern G. acanthochirus. Taxonomic placement of single specimens from other localities was confirmed by multivariate methods. Furthermore, Glypturus is revised extensively, especially with regard to Western Atlantic species that inhabited both carbonate and siliciclastic environments. Minor propodi appear underrepresented relative to major propodi suggesting a taphonomic bias. Single specimens of interest include a specimen of G. n. sp. 1 exhibiting a peculiar swelling in the fixed finger and another specimen showing damage on the upper margin of the propodus, suggesting failed predation or antagonistic behavior. Glypturus is first found in the Oligocene of the Western Atlantic and may have expanded its paleobiogeographic range since the Miocene. Glypturus is still found on the Pacific side of the Isthmus of Panama in the Holo-Pleistocene, but is only known from the Western Atlantic today, suggesting a relatively recent extinction of this genus in this part of the Pacific. This study highlights the usefulness of multivariate and geometric morphometric methods in systematic paleontology.