Ten-month-old Darina Gromova from St Petersburg had been on holiday in Sharm el-Sheikh with her parents when they, and 221 others, died shortly after their flight to Russia took off on Saturday.
The baby girl's body was found more than 21 miles from the main crash site, indicating that the plane may have exploded earlier than aviation experts had previously thought.
That has forced investigators to widen the search area - and could lead to the discovery of otherwise missed clues.
Tragedy: The discovery of little Darina's body, pictured at a St Petersburg airport shortly before the young family set off for Egypt, may help solve the question of what happened to the Airbus A321 before it went down