دانلود کتاب Cretaceous and Eocene Decapod Crustaceans from Southern Vancouver Island, British Columbia, Canada

A large collection of fossil decapod crustaceans from Cretaceous and Eocene rocks of Vancouver Island, British Columbia, Canada, has yielded a remarkably diverse fauna. The Cretaceous decapod fauna, including previously described and new taxa, contains 17 genera in 14 families, represented by as many as 22 species. The Eocene fauna is less robust, with 7 species and 6 genera in 6 families. This publication includes one new family; three new genera; eight new species; and, nine new combinations. The decapod fauna of the Nanaimo Group supports a position for Wrangellia well north of the current position of Baja California, Mexico. The decapod fauna of the Western Interior of North America is distinct from that of west coastal North America, suggesting limited faunal exchange between the two areas. Fewer than half of the decapod genera present in British Columbia during the Late Cretaceous Period became extinct by the end of the Cretaceous, most before the Maastrichtian. Two of the Cretaceous genera and none of the Eocene genera are extant; the extant genera are both members of the Callianassidae. Of the 14 families present in Cretaceous rocks of British Columbia, five are extinct. The North Atlantic and Central Americas appear to have been areas of rapid evolutionary expansion within the Decapoda during the Cretaceous, based upon the large number of decapod families that appear to have originated there during Cretaceous time.