Simplify the following text for a Grade 12 native English-speaking person.
Original: The Eumuroida is technically defined as the clade including all organisms descended from the most recent common ancestor of the Calomyscidae , Nesomyidae , Cricetidae , and Muridae .
Simplified: The Eumuroida is the clade including all organisms which evolved from the most recent ancestor of the Calomyscidae , Nesomyidae , Cricetidae , and Muridae .