Spray et al. postulate that five widely dispersed terrestrial impact structures with very similar geological age estimates (about 214 million years ago, in the Late Triassic epoch) are evidence of a multiple impact event. Most notably, the three largest impact structures, Saint Martin in western Canada (~40 km diameter), Manicouagan in eastern Canada (~100 km diameter), and Rochechouart in France (~25 km diameter), plot at virtually the same palaeolatitude in a continental reconstruction. Spray et al. suggest that this apparent crater chain was produced within hours as a series of coaxial projectiles collided in rapid succession with the rotating planet Earth, and drew analogies to the recent collision sequence of fragmented comet Shoemaker-Levy 9 with Jupiter. However, published palaeomagnetic data for the Manicouagan and Rochechouart impact structures argue strongly against such a closely timed origin for these ancient events. This is because the characteristic remanent magnetizations of the melt rocks, including the most rapidly cooled glassy phases, indicate formation in a Late Triassic palaeomagnetic dipolar field of normal polarity at Manicouagan but of reverse polarity at Rochechouart.