In the osm database, sites with fossils have the tags geological=palaeontological_site , see Tag:geological=palaeontological_site - OpenStreetMap Wiki and taginfo counts.
But, when we search for information on the Internet, the result is almost Paleontology (without “a” at the 4th place) : on wikipedia, on britannica.com, on cambridge.org to give examples of important websites found with a search.
Why not use the most common spelling ?
The short version is American English and the long version is British English. There are more Americans and therefore the American version is used by more people. OSM is however British and not American.
or more specifically for this case: OSM tagging dialect prefers British spelling
I just saw that the site cambridge had both dictionary and was able to show the differences = PALAEONTOLOGY | English meaning - Cambridge Dictionary
Good to know I think.