[SunkenCiv]

Including the H is the way the English decided to do it, "-tal" is from the German original. I'm drawing a blank on what "Google search drop" means.

[9YearLurker]

Articles in English, of course, should use English spellings. IMO.

[Verginius Rufus]

When the first Neanderthal discoveries were made, "thal" was the German spelling. The German spelling was reformed later--the "th" was pronounced like "t"--but the original version of the name had become well known by then.

"Thal" is cognate with the English word "dale."

The German book Die Neandertaler by Friedemann Schrenk and Stephanie Mu+ller was translated into English and published as The Neanderthals.