Forget Asteroids—New Theory Says Dinosaurs Were Already Dying Before Earth Got Hit
At this point, most scientists agree that a giant asteroid impact wiped out the dinosaurs—we have the Chicxulub crater to prove it. But the picture may have been more complicated than that.
According to new research by two professors from the University of Albany and the University of Baltimore, dinosaurs were already dying off in large numbers due to their inability to deal with new, toxic plants.
According to the new theory, dinosaur populations were gradually disappearing before the asteroid impact, apparently due to the emergence of angiosperms, a type of flowering plant.
It's hypothesized that angiosperms began developing toxic defense mechanisms to survive, an adaptation that the dinosaurs couldn't cope with due to their inability to develop "learned taste aversion," a mechanism that lets animals associate the taste of something toxic with the feeling of being sick.
Learned taste aversion is one of the key reasons rats are so difficult to kill.
According to Gordon Gallup, one of the professors involved with the study:
"A reason why most attempts to eliminate rats have not been successful is because they, like many other species, have evolved to cope with plant toxicity. When rats encounter a new food, they typically sample only a small amount; and if they get sick, they show a remarkable ability to avoid that food again because they associate the taste and smell of it with the negative reaction."
Two species that have evolved from dinosaurs, birds and crocodilians, showed very different capabilities when it comes to recognizing toxic objects: birds learned to recognize toxic food sources based on their visual features (rather than taste), but crocodilians showed no ability to connect toxic food to the feeling of sickness.
According to Gallup:
"Though the asteroid certainly played a factor, the psychological deficit which rendered dinosaurs incapable of learning to refrain from eating certain plants had already placed severe strain on the species. The prevailing view of dinosaur extinction based on the asteroid impact implies that the disappearance of dinosaurs should have been sudden and the effects should have been widespread, but the evidence clearly shows just the opposite: Dinosaurs began to disappear long before the asteroid impact and continued to gradually disappear for millions of years afterward."
In terms of dinosaur disappointments, this discovery may rank right behind learning that velociraptors had feathers. Extinction from a giant, unstoppable asteroid seems nobler than being too stupid to stop eating toxic plants.