The reason Dolphins received so many votes ... this was the height of the TV Program "Flipper" era.
Somewhere, I read that the money-man (true owner) Danny Thomas (also a big/rich TV Star in that era) ... liked the Dolphin name & pushed it through.
Danny Thomas even pushed his idea (good marketing) & bought the tank with dolphin in the end zone.
Anywho, not that any of it really matters ... but is interesting to put it all in context of the time, the "60's TV Era."