Dark matter accounts for up to 85{154653b9ea5f83bbbf00f55de12e21cba2da5b4b158a426ee0e27ae0c1b44117} of the matter in the universe – but does not emit radiation (such as light), interacting with ordinary matter only via gravity.
Lisa Randall, the author of Dark Matter and the Dinosaurs, believes the dinosaurs may have been wiped out when Earth passed through the dark matter in the Milky Way’s disc.