Question mark
In the early 13th century, when the growth of communities of scholars (universities) in Paris and other major cities led to an expansion and streamlining of the book-production trade, punctuation was rationalized by assigning Alcuin's stroke-over-dot specifically to interrogatives; by this time the stroke was more sharply curved and can easily be recognized as the modern question mark.
Exclamation mark
Some comic books, especially superhero comics of the mid-20th century, routinely use the exclamation point instead of the period, which means the character has just realized something; unlike when the question mark appears instead, which means the character is confused, surprised or they do not know what is happening. This tends to lead to exaggerated speech, in line with the other hyperboles common in comic books. A portion of the motivation, however, was simply that a period might disappear in the printing process used at the time, whereas an exclamation point would likely remain recognizable even if there was a printing glitch. For a short period Stan Lee, as Editor-in-Chief of Marvel Comics, attempted to curb their overuse by a short-lived ban on exclamation points altogether, which led to an inadvertent lack of ending punctuation on many sentences.