Image Source: TGLDirect.com
It did, indeed, come from a gas station promotion - different animal with each purchase.
I had one of these sets when I was five years old. I remember losing one of the hippos. It happened when I took the set to a neighbor’s house to play with it while she babysat my sister and me on the day our younger brother was born.
She was a very nice lady. She thoroughly searched her house several times trying to find my missing hippo, but it was never found.
The entire memory of that event just now flooded back to me when I saw that picture. It’s amazing what a simple image can do.
Oh dear, that couldn’t be done today...the anti reglious jerks would protest the gas station’s headquarters...