The Dolphins began as an AFL team in 1966 and entered the NFL in the 1970 merger of the two leagues.
the MIAMI DOLPHINS went undefeated in the year 1972
The Miami Dolphins play football. The Miami Dolphins are one of the older franchises in the National Football League (NFL). The Dolphins are the only franchise in NFL history to ever have a perfect season. There quarterback that year...Dan Marino.
The Vikings joined the NFL as an expansion team in 1961.