2015 GSA Annual Meeting in Baltimore, Maryland, USA (1-4 November 2015)

Paper No. 163-8
Presentation Time: 3:35 PM

EYES AND CLAWS REVEAL THE EVOLUTION OF DIVERGENT ECOLOGICAL ROLES IN GIANT PTERYGOTID EURYPTERIDS


MCCOY, Victoria E., Geology and Geophysics, Yale University, New Haven, CT 06520, LAMSDELL, James C., Department of Geology and Geophysics, Yale University, Kline Geology Laboratory, 210 Whitney Avenue, New Haven, CT 06511, POSCHMANN, Markus, Referat Erdgeschichte, Direktion Landesarch├Ąologie, Generaldirektion Kulturelles Erbe RLP, Gro├če Langgasse 29, Mainz, 55116, Germany, ANDERSON, Ross P., Geology and Geophysics, Yale University, 210 Whitney Avenue, New Haven, CT 06511 and BRIGGS, Derek E.G., Peabody Museum of Natural History, Yale University, 170 Whitney Avenue, New Haven, CT 06520-8118, victoria.mccoy@yale.edu

Pterygotid eurypterids have traditionally been interpreted as active, high-level, visual predators; however, recent studies of the visual system and cheliceral morphology of the pterygotid Acutiramus contradict this interpretation. Here we report similar analyses of the pterygotids Erettopterus, Jaekelopterus, and Pterygotus, and the pterygotid sister taxon Slimonia. Representative species of all these genera have more acute vision than A. cummingsi. The visual systems of Jaekelopterus rhenaniae and Pterygotus anglicus are comparable to that of modern predatory arthropods. All species of Jaekelopterus and Pterygotus have robust crushing chelicerae, morphologically distinct from the weaker slicing chelicerae of Acutiramus. Vision in Erettopterus osiliensis and Slimonia acuminata is more acute than in Acutiramus cummingsi, but not to same degree as in modern active predators, and the morphology of the chelicerae in these genera suggests a grasping function. The pterygotids evolved with a shift in ecology from generalized feeder to specialized predator. Pterygotid eurypterids share a characteristic morphology but, although some were top predators, their ecology differs radically between genera.