Where is this? Can anyone tell? When is sometime in the 70s.

This is kids on a triceratops. There may be one or two others. Maybe a stegosaur? Any ideas?  This might be DC, somewhere near the Smithsonian, but I don’t know if this stuff even exists anymore.  A million, Billion E-dollars* for the first correct answer, with a link or useful pictures.
*no cash value in the reality based world, but maybe a grant if authorship privileges or something.