I suspect* sometimes it was. It wouldn’t have been the case that all species were either eliminated or unaffected; those species that survived would have lost some of their population, whether through starvation from insuffiecent food to support large size, inability to hibernate for long enough or simply incapability of holding their breath underwater while the fireball raged above. All these traits vary across a single species.
*Deliberate British understatement highlighted for international audience.