At the recent conference of European cryptozoologists, on the 16th and 17th of April 2011, Catherine Gravet gave a passionate presentation on the influence of Bernard Heuvelmans on Herge and the Tintin series.
The collaboration of Bernard Heuvelmans with Herge, as demonstrated within “Tintin au Tibet” is somewhat known in cryptozoology circles.
Here you can see how Heuvelmans’ drawing of the Yeti guided the author of the comics (early forms of graphic novels, really), as well as did the images shared from the 1951 Shipton encounter with the footprints in Nepal.
The appearance of the condor (a vulture) vs the eagle carrying away prey is to be found in the Tintin series too. Did Heuvelmans have a hand in this? The condor-like bird mirrors the description of a Thunderbird.
For more on this cryptozoological topic, in French, see here.
What is less well known is that Bernard Heuvelmans appears to have given Herge the idea to place water on the moon, and this concept has turned out to be real. (More on the moon angle, in French, here.)
As to mammoths on the moon, well…
My thanks to Michel Raynal for this information.