All life on Earth is trying to survive, and some species have advantages over others. Now, researchers are investigating how certain species withstand the incredible stress they experience during mass extinctions, while others simply perish. And by looking at what happened during the Great Dying, they've managed to find some clues.  

This mass extinction happened 252 million years ago between the Permian and Triassic periods and in some ways is similar to what’s happening today. A rapid increase in global temperatures, a drop in oxygen, and the acidification of oceans killed 96 percent of all marine life and 70 percent of all terrestrial vertebrates. Certain areas showed a quicker recovery than others, and researchers are interested in finding out why.

The team examined the fossils of ocean-dwelling invertebrates such as clams, snails, corals, and sponges. As reported in the journal Biology Letters, they witnessed a continuity in traits among species that died in the extinction and species that arose afterward. But one remarkable difference was that the later species were bigger and more active than the older ones. Better defensive mechanisms for prey and more agility for predators also appeared after the extinction. 

"We're interested in understanding why certain species and communities survived and recovered better than others," lead author Dr Ashley Dineen, from the University of California Museum of Paleontology, said in a statement. "For a long time biology has focused on the number of species that survive extinction events, but we need to also ask what those species did and how they reacted to stresses – these insights are important as we push our planet into an increasingly uncertain future."

The team is now interested in working out what species are the best at recovering from dramatic climate changes. They would like to see if certain stressors impact every being in a particular ecological niche equally or if some species have an advantage from the beginning. This could provide us with very important information on how best to save certain natural habitats. 

"We're often focused on estimating the number of species in an ecosystem, but we should also be learning about how – and how well – these species survive, and concentrate conservation efforts accordingly," said Dineen. "When you consider the mass extinction we face today, it's clear we have to take entire systems into account before it's too late to correct course."

During the Great Dying, volcanos are thought to have injected huge amounts of greenhouse gases into the atmosphere. They released CO₂ at a similar rate to today's human-made emissions, but over a time period of 10,000 years.