It can be argued that the Cambrian "explosion" was quick, if you think millions of year is quick;-)
There are no serious questions about evolution. If there were, it would no longer be held by science as a theory. A theory is the underlying principles that tie data together. In this case there are mountains of data supporting the Theory.
Please list your serious "questions" for discussion:
(I have had a hard day and need a good laugh-thank you)
The other issue with the Cambrian explosion is that 'evolution' appears to have occurred 'from the top down' so to speak. In other words, complex creatures suddenly appear with no fossil evidence of any transition from previously existing life forms. Then, after that, small changes occur in those complex creatures. (Evolutionary theory would claim a 'bottom to top' formation of life, i.e. that the small changes would result in complex creatures over millions of years.)
"There are no serious questions about evolution."
Sorry, but I've just listed one.
"Please list your serious "questions" for discussion"
As I mentioned earlier to a number of individuals on this thread, if you are truly interested, there's plenty of reading material available. "The Case for a Creator" by Lee Strobel would be a start.
" (I have had a hard day and need a good laugh-thank you)"
Ah, so you really aren't interested. Don't want anyone to upset your preconceived notions, now do you?