  Studies of micrometeorites in mid-Ordovician limestones and Earth's impact
craters indicate that our planet witnessed a massive infall of ordinary L
chondrite material 466 million years (My) ago (Heck et al. 2017, Schmieder &
Kring 2020, Kenkmann 2021) that may have been at the origin of the first major
mass extinction event (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 (>20% of
all falls) (Swindle et al. 2014). Here, we provide spectroscopic observations
and dynamical evidence that the Massalia collisional family is the only
plausible source of this catastrophic event and of the most abundant class of
meteorites falling on Earth today. It is suitably located in the inner belt, at
low-inclination orbits, which corresponds to the observed distribution of
L-chondrite-like near-Earth objects (NEOs) and of interplanetary dust
concentrated at 1.4 degrees (Sykes 1990, Reach et al. 1997).
