THE RICHEST CRETACEOUS DECAPOD LOCALITY IN THE WORLD? – AN UPDATE

Following the peak diversity of decapods during the Late Jurassic, the number of taxa dropped significantly at or just prior to the Jurassic-Cretaceous boundary. This could be due to the collapse of reefs, especially coral reefs which provide numerous niches in which decapods thrive. In the course of the Cretaceous, decapod communities partly recovered in a variety of sedimentary environments. This is exemplified by mid-Cretaceous and Late Cretaceous localities/formations yielding numerous decapods. For example, the lower Cenomanian chalk/glauconitic sands of Petréval (France) yielded some 26 decapod species; 29 species were encountered in the coral containing Maastrichtian limestones of the Maastricht Formation in the Netherlands; the sandy Cenomanian deposits near Devon, Great Britain, yielded as many as 27 species; and 23 species have been found in the Albian/Cenomanian reefal limestones of Monte Orobe (Spain). Less diverse localities/formations can be found in the United States, Lebanon, Japan, and in other parts of Europe. We report on decapods collected at the disused Koskobilo quarry (Eguino Formation, Albeniz unit) in Navarra, northern Spain. The locality is situated on the edge of the Aldoirar patch reef, where reefal debris can be found as well as an in situ coral patch. Fieldwork in 2008 and 2009 has already yielded about thirty species. New fieldwork in the summer of 2010 and ongoing study of all the specimens adds more species to list of decapods from Koskobilo. As a result, Koskobilo is likely to become the richest Cretaceous decapod locality in the world; the Eguino Formation the richest Cretaceous formation. Only crabs have been discovered so far. Species ascribed to the Galatheoidea, Homolodromioidea, and Homoloidea are most abundant. Fieldwork in Koskobilo was partly supported by a Molengraaff Fonds, Amoco Alumni Scholarship, Graduate Student Senate (Kent State University) research grant, Sigma Gamma Epsilon (Gamma Zeta Chapter) research grant to Klompmaker, and an NSF grant EF0531670 to Feldmann and Schweitzer.