found 'em! posters my dad brought back from san francisco in summer 1966 (&, as an art student, thought to keep them flat), part 1. some BGP classics.

@bourgwick Thanks for sharing to take me down the rabbit hole. Seeing The Turtle’s turtles with 66 under it made me wonder about a connection between it and Terrerapin being out in 1977. Learned something new!

https://extrachill.com/grateful-dead-terrapin-turtles-meaning/

The History and Meaning of the Grateful Dead Terrapin Turtles – Extra Chill

One of the lesser-known but still beloved Grateful Dead logos are the terrapin turtles. First pictured in the cover art for the 1977 album Terrapin Station,...

Extra Chill
@Brian yup, the heinrich kley turtles! i'd never noticed until today that they actually credit kley on the turtles poster.