Where?
***”hellish environment” around 65 million years ago and wiped out more than half of all species on the planet.***
According to the math - half the species survived whatever cataclysmic event supposedly occurred. It is not clear that all areas of the Earth were impacted...only those areas inhabited by the creatures that died off.
Considering that most insects’ life span is only a few days - their replacement rate may not have been affected at all.
I suspect that gases and chemicals spewed out in the limited areas that dinosaurs inhabited - may also have caused a type of sterility by absorption into the food chain.
Only God knows.