Part of the reason a mushroom would be so tall is that when the cap opens, the stem is connected to the middle. So a mushroom top that is say, 10 feet across, would be at the very least 5 feet tall. As the top gets heavier the stem would have to be larger in diameter to hold up the increased weight.
It's also not uncommon to find fungi that are several feet long growing on trees and such. Not sure if the article specifically said mushroom or if it was just a fungi they found a fossil of.
It's also not uncommon to find fungi that are several feet long growing on trees and such. Not sure if the article specifically said mushroom or if it was just a fungi they found a fossil of.