USA's Shamier Little, a first-year student at Texas A&M University, dominates the 2014 junior list with seven of the eight best performances this year.
Her three best all came on the same Hayward Field track which will host the IAAF World Juniors Championships, in the rounds and final of the NCAA Championships, then in the USA Junior Championships in a year-leading 55.07.
"At the Worlds, Im looking to atone for 2012, when I fell at the final hurdle and didn't finish in the final," said Little recently.
Following Little, Great Britain's Shona Richards has marks 9-12 on the 2014 list starting at 56.79; Little’s team-mate Jade Miller then joins the list at 57.22. Those three hold 17 of the 20 fastest marks of the year.
Parker Morse for the IAAF