As the East Pacific Rise approached and impinged upon the western margin of North America, the farallon plate began to break into multiple smaller plates, whose relative movements changed strongly from those before breakup. Movements of the northern Cocos plate, inferred from magnetic lineations, show rapidly changing rates and pole positions which may be characteristics of other small remnants of the farallon plate. Finite difference poles and rates for Cocos-Pacific relative motion during the time intervals 2--5, 5--7, 7--10, and 10--14 m.y. have been determined from the geometry of magnetic isochrons. Prior to about 2 m.y. the Cocos-Pacific pole was 10¿ to 20¿ south of its present location, and angular rates were 2--4 times the present rate. From 10--7 m.y., we deduce a large degree of oblique convergence between the Cocos and North American plates, which may be an important constraint on the evolution of the structure of the continental margin of southwestern Mexico. The Tehuantepec Ridge originated as the ridge-ridge transform which generated the Clipperton fracture zone. Spreading rate estimates for the southern part of the Cocos plate suggest the possibility that the Tehuantepec Ridge was reactivated as a ridge-trench transform between the two Cocos plate fragments prior to about 7 m.y.