Simplify the following text for a Grade 9 native English-speaking person.
Original: Michael Rogers Oldfield Thomas ( usually known as Oldfield Thomas ) FRS ( February 21 , 1858 -- June 16 , 1929 ) was a British zoologist .
Simplified: ( Michael Rogers ) Oldfield Thomas FRS ( February 21 , 1858 -- June 16 , 1929 ) was a British zoologist .