There's been a lot of good work on this, but it's now pretty clear that people were seriously overthinking why ancient insects got so large: they had a first mover advantage on land and in the air. As land-fish caught up, insect sizes were increasingly suppressed
Asher Elbein
“This study places what may be the final nail in the coffin for the prevailing view that more oxygen made ancient insects bigger.”
Learn more: https://scim.ag/4vcqqS8
Flying insect respiratory systems suggest abundant oxygen can’t explain ancient gigantism
