A long-held theory suggests that the asteroid strike that killed off non-avian dinosaurs — and most large marine predators — 66 million years ago created an ecological opportunity that spurred the rapid evolution of tunas, and other large, fast, and warm-blooded predators. 

The idea is that tunas and their carnivorous counterparts filled a niche left by their massive, predatory predecessors, much like how mammals replaced the world’s non-avian dinosaurs after the K-Pg extinction event. 

But that theory doesn’t quite hold water, according to a new Yale study that provides new insights into how these economically important fishes evolved their imposing size, speed, and ability to regulate their body temperatures in cold seas. 

Oceanographers have conducted a comparative study in Belgium and Africa on the microbial oxidation of methane in rivers - a natural process whereby certain bacteria consume this powerful greenhouse gas before it is released to the atmosphere. Thisresearch reveals that this biological filter, which is more active in African rivers than in Belgian ones, remains insufficient to offset the rise in methane emissions expected because of global warming and nitrate pollution.