Simplify the following text for a Grade 14 native English-speaking person.
Original: Simpson was perhaps the most influential paleontologist of the twentieth century , and a major participant in the modern evolutionary synthesis , contributing Tempo and mode in evolution ( 1944 ) , The meaning of evolution ( 1949 ) and The major features of evolution ( 1953 ) .
Simplified: Simpson was perhaps the most influential paleontologist of the twentieth century , and a major participant in the modern evolutionary synthesis .