Sierra McCormick was 10 in Land of the Lost when she played the character 'Tar Pits Kid'.
That was over 15 years ago in 2009.
This was her first recorded movie acting credit (although may not technically be her first actual acting role).
Today she is 26, and has starred in 21 movies in total, 17 of those since Land of the Lost was released.
In Land of the Lost, I think Sierra McCormick looks: