the gmr writes:
Gordon Gallup, professor of Evolutionary Pyschology at the University at Albany New York, and Michael Frederick of the University of Baltimore recently published a paper in the peer-reviewed journal Ideas in Ecology and Evolution asserting that failure to develop taste aversion to toxic plants was killing off the dinosaurs long before the massive asteroid primarily believed to be the cause of their extinction struck the earth. As reported at the site phys.org, the dinosaur population had been drastically decreasing before the asteroid impact. Gallup and Frederick cited that the appearance of the first flowering plants--angiosperms--in the fossil record coincides with the gradual disappearance of the dinosaurs. "Gallup and Frederick claim that as plants were evolving and developing toxic defenses, dinosaurs continued eating them despite gastrointestinal distress."
As a point of comparison for evolutionary development of taste aversions, Gallup and Frederick examined the abilities of creatures believed to be descended from dinosaurs: birds and crocodilians.They found that the birds, rather than forming aversions to taste, developed aversions to the visual features of whatever made them sick. Still, they knew what they shouldn't eat in order to survive. In a previous study in which 10 crocodilians were fed different types of meat, some slightly toxic, Gallup discovered that like dinosaurs, crocodilians did not develop learned taste aversions.
The scientists concluded that though the asteroid played a role in the extinction of dinosaurs, the "plants had already placed severe strain on the species," Gallup said.
"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."
