Quoting a sign in Redwood National Park:
Redwoods once covered large expanses of the world. Millions of years ago some of these redwoods were preserved as fossilized trees when volcanic ash buried them. Over time, the trees absorb silica from the ash, creating a stone replica. Where living tissue once was, rock now exists.
In North America, redwood fossils have been found in Texas, Pennsylvania, Colorado, Wyoming, Oregon, Washington, California, Canada, Greenland, Alaska, and St. Lawrence Island. In Europe, fossils of redwoods have been found in France, Switzerland, Austria, Bohemia, Germany, England, and Spitzbergen. You can see fossil redwoods for yourself by visiting Yellowstone National Park in Wyoming, Florissant Fossil Beds National Monument in Colorado, or The Petrified Forest in Calistoga, California
The height of S. sempervirens is closely tied to fog availability; taller trees become less frequent as fog becomes less frequent. As S. sempervirens' height increases, transporting water via water potential to the leaves becomes increasingly difficult due to gravity
If you put those two facts together than it seems like either (1) the vast majority of the redwoods that existed millions of years ago fell short of their full potential height or (2) the Earth, millions of years ago, was a lot more foggy than it is today?
If the latter than why would the Earth have been so much foggier?