Because the 1960 Cadillac’s fins had shrunk many see that year as the beginning decline of the tail fin. The tail fin was not done yet it was just finding new areas to explore, like young plants trying to find new, fresh habitat in a dense forest.
Chevy’s 1959 & 1960 models and Ford & Edel’s 1960 model turned the fins on their sides to create wings.
1959 & 1960 Buick, 1960 & 1961 Chrysler and Desoto ran with and expanded the canted, diagonal fin seen on earlier Thunderbirds and Lincolns.
Tubes in circular or oval shapes also sat on the top edges of rear fenders as seen on 1959 Fords, Pontiacs and Oldsmobiles. Pontiac even capped off each of the tubes with a pair of fins.
Dodge strayed from the traditional vertical fin in 1960 and 1961 also. The 1960 Dodge Matador and Polara clipped the fins off ¾ of the way down the rear fender. In 1961 the fin would peak behind the rear window and gradually fade down as it reached the end of the trunk.
Mercury and Rambler did not have large fins in 1960 but both had a cute little curve in the tip of the fins.
Oldsmobile and Cadillac, in 1961, both figured that the pinnacle of the upward vertical fin had been achieved and sprouted diagonal downward fins, often referred to as skegs.
Studebaker, Plymouth almost all the rest had an interpretation of the fender capping tail fin. Even stalwart function before form stalwarts Mercedes and Volvo produced cars with tail fins.
Love your site. I thought I would pass along this picture of our house in small-town Newark, Delaware, 1955, complete with the car with fins in the driveway. When I was born, a year before this was taken, it was to this house that I came home.