U.S.A., 1946

Smithsonian centenary FDC

I have thought for years that prehistoric life entered philately on the tenth of August, 1946, with this American FDC, and that the theme 'Prehistoric life in Philately' was born on this date.
On this date, a stamp was issued to celebrate the centenary of the Smithsonian Institution.
The stamp itself shows the Smithsonian's buildings in Washington, but the illustration on the left side of the FDC shows a sauropod, most likely a Diplodocus, judging from the long, thin neck and tail.
Recently, however, I found out that I was wrong.
It turns out that there is an even earlier item!