In a recent paper [Science 291 (2001) 1530] Becker et al. explain the greatest extinctions in the earth history at the P/Tr boundary by the impact of an extraterrestrial object and consider that hypothesis proven by the presence Of C-60 and C-60, endohedrally filled by extraterrestrial helium and argon isotope ratio they determined in P/Tr boundary layers. This paper raises some analytical aspects of those determinations which do not seem to be sufficiently well founded.