summer olympics competed summer olympics london held july august country participation london marked eighth appearance summer olympics debut summer olympics delegation included track field athletes selected team places nation athletes met qualifying standards selected flag bearer opening ceremony carried closing ceremony athletes progressed heats background participated summer olympic games debut summer olympics los_angeles united_states summer olympics london participate summer olympics july august selected athletes usually able enter qualified athletes individual event long athlete met standard athlete event met standard athletes met standard allowed select athletes gender athletes selected compete london games men meters women meters flag bearer opening ceremony held closing ceremony athletics making summer olympics debut notable carrying flag opening ceremony qualified summer olympics best time seconds seconds slower qualifying standard event meters competed august heat seven athletes ran time seconds finishing achieving personal best time ranked ahead time seconds heat led eventual gold medalist event jamaica bolt seconds overall ranked 53rd athletes competing seconds slowest athlete progressed semi finals end competition competing summer olympics qualified london games set time event meters compete world junior championships athletics meters start event competed august heat seven athletes posted time minutes seconds finishing sixth setting national record process placed ahead palestine minutes seconds canada minutes seconds heat led ukraine minutes seconds overall fall seconds slowest athlete progressed semi finals advance ranks given track events athlete heat qualified round qualified round fastest loser field events position achieving qualifying target national record round applicable event bye athlete required compete round
Mauritania at the 2012 Summer Olympics