NEOHELICE (DECAPODA: BRACHYURA: VARUNIDAE) FROM THE MIDDLE HOLOCENE, CANAL DE LAS ESCOBAS FORMATION, NORTHEASTERN BUENOS AIRES, ARGENTINA -- Preprint doi:10.5710/AMGH.16.05.2019.3243

Cristian A. Pereyra, Enrique Fucks, Rodney Feldmann

Abstract


Neohelice granulata Dana 1851 is an endemic, burrowing intertidal species of crab distributed in mudflats and saltmarshes of bays and lagoons along the coast, from southern Brazil to northern Patagonia (Argentina). It is widely known in modern population studies dealing with ecology, genetics, physiology, and burrowing. However, it is known in the fossil record only from the middle Holocene from Buenos Aires, the last marine transgression. The material comprise eleven almost complete specimens, six isolated carapaces, seven isolated chelipeds, preserved in micritic and sandy concretions of different shape and size, formed within their burrows. Diagenetic processes produced dorsoventral crushing of all of the specimens to different degree but generally well preserved. No burrows were unambiguously identified, but the articulated nature of the exoskeleton suggests preservation within burrows. A winter kill might have been the cause of this assemblage, which also includes molluscs, cirripeds, and vertebrates. Herein we describe in detail for the first time this material from Pereyra Iraola Park, Canal de las Escobas Formation, Destacamento Río Salado Member, taphonomy and discuss the paleoenvironmental implications.

Full Text:

 Subscribers Only