Studies of micrometeorites in mid-Ordovician limestones and Earth’s impact craters reveal that our planet experienced a massive infall of ordinary L chondrite material approximately 466 million years ago. This event is believed to have triggered the mid-Ordovician ice age, sea level fall, and major faunal turnovers (Schmitz et al. 2019). The breakup of a large asteroid in the main belt is the likely cause of this massive infall. In modern times, material originating from this breakup still dominates meteorite falls (37% of all falls). I will present spec- troscopic observations and dynamical evidence showing that we have identified the only plausible source of this remarkable event and the most abundant class of meteorites falling on Earth today.
