What killed the dinosaurs? Experts are yet to agree on a single answer, but there is a wealth of potential reasons why these creatures vanished on the face of the earth 66 million years past.
A recent study particularly proposes that the volcanism theory might not be the cause. Published Nov. 23 in the journal Nature Geoscience, the research showed that climate change stemming from continental flood basalts – the massive and long-running volcanic eruptions taking place around the time of the great asteroid impact – might have been quite minor.
The research team out of the University of Leeds gathered data from previous studies, and said that the situation likely "wasn’t that grim." This is contrary to beliefs that the cooling due to years-long sulphur dioxide emissions killed off all plants and animals, including dinosaurs.
“I felt that a lot of people, when they tried to make statements about how much volcanism contributed — it was all very qualitative,” said Anja Schmidt, lead researcher of the study.
Schmidt explained that for the cooling to happen long enough to incite a mass extinction, the volcanic eruptions needed to occur for a century or longer, something much more protracted than ever estimated.
So whodunit? There are many speculations on why dinosaurs became extinct, including the following:
- Atmospheric changes – High carbon dioxide levels might have destroyed dinosaur embryos, or extremely low levels removed the “breathing stimulus” of warm-blooded ones. The oceans might have also stagnated or lacked the oxygen for marine species – assuming all dinosaurs populated marine environments.
- Climate change – It could have been too much CO2 levels; too cold, too wet, or too dry climates; or even a nearby supernova explosion that imposed great stresses upon the dinosaurs and made them unable to adapt sufficiently and on time in order to survive.
- Competition with other animals – Theories proposed here include caterpillars consuming all the plants and left nothing for the herbivores, changes in dinosaur DNA, disease epidemics, and increasing entropy wiping out larger organized life forms.
- Floral changes – Could it be that there was rapid fungi evolution, massive loss of habitats, or plant diversification that deprived herb-eating dinosaurs of their food?
- Other mass-scale changes – These could include sudden atmospheric heating, an asteroid impact, interstellar dust clouds, ionizing radiation, or a widespread infection.
The correct answer eludes scientists until present, but for Schmidt, it is important to pin down the real cause of dinosaur extinction as the planet hurtles toward another mass extinction – one that is definitely man-made.
"A group of really powerful and intriguing species went extinct, and it’s important to understand because it happened very fast, and we don’t have a universal agreement about how," Schmidt said.
Photo: Dave Catchpole | Flickr