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Poisonous Plants, Not an Asteroid, May Have Killed the Dinosaurs

Although we’ve dug up their bones and given them names, dinosaurs remain one of Earth’s greatest mysteries. These amazing monsters of all shapes and sizes roamed the earth millions and millions of years ago and then just died, or evolved into chickens.  That an asteroid or comet impact was responsible for the extinction of dinosaurs is widely regarded as the most likely theory. Now, two scientists have come forward with a different explanation for what happened to the dinosaurs. They say it was poisonous plants and dinosaurs’ inability to adapt to the increasing toxicity of their food, rather than a giant fireball  from the sky, which caused the extinction of those prehistoric monsters.

The new paper, published in the peer-reviewed journal Ideas in Ecology and Evolution, comes from evolutionary psychology professor Gordon Gallup from the University of Albany and his former student Michael J. Frederick, now at the University of Baltimore. They don’t deny that an asteroid or comet impact probably happened, but they suggest that dinosaurs were already on their way out by the time it hit.

What killed the dinosaurs?

What’s scarier, poisonous plants or world ending asteroids?

The scientists put forward that as toxic plants began to emerge in Earth’s prehistoric wilds, dinosaurs weren’t quick enough to develop “learned taste aversion,” an evolutionary trait by which species learn to identify toxic food by associating the taste of the food with negative effects. To explain the idea of learned taste aversion, Gallup uses the example of why rats are so hard to eliminate:

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.

Crocodiles are related to dinosaurs.

Crocodiles are believed to be one of the closest modern relatives to dinosaurs.

It’s unclear exactly when these toxic plants first came into existence, but Gallup and Frederick say that it coincides with the decline of the dinosaurs. As evidence of this, they point to the fact that when the asteroid hit, it didn’t wipe out all of the dinosaurs all at once. Also, they point to research they did on birds and crocodiles, believed to be the closest modern relatives to dinosaurs, and they found that birds rely on visual cues to alert them to poisonous plants, while crocodiles are extremely slow to manifest learned taste aversion. Gallup says:

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

Personally, I hope this theory turns out to be false. Being slowly poisoned by your food and bad sense of taste is a far less dignified way to go than getting knocked on the head with a giant comet. The dinosaurs were awesome, and they deserved better.