6076
6,331 genes common to all living animals have been identified ; these may have arisen from a single common ancestor that lived 650 million years ago in the Precambrian .
 location: Precambrian
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: location, person, organization 
Text: {0} 
 Entities: Precambrian 
Answer:
 location: Precambrian