Did Insects Cause the Dinosaur Extinction?
Most people believe that an asteroid wiped out the dinosaurs. But what if the culprit was actually something much smaller, yet with a more lasting impact: insects?
Husband-and-wife entomologists George and Roberta Poinar believe that insects played a major role in the extinction of the dinosaurs. In their book, “What Bugged the Dinosaurs? Insects, Disease, and Death in the Cretaceous,” they argue that an asteroid or volcanic eruption alone cannot explain why the dinosaurs died off over hundreds of thousands of years. While these catastrophic events likely had some impact on dinosaur populations, they don’t fully account for the mass extinction.
The Poinars studied ancient plant and insect species that were trapped in drops of amber millions of years ago. In the gut of one amber-preserved bug, they found a pathogen that causes leishmaniasis, a parasitic disease that can infect reptiles. In another, they found pathogens for malaria. They also examined fossilized dinosaur feces and discovered evidence of dysentery and other intestinal parasites, most of which are transmitted by insects.
The tropical climate of the Late Cretaceous would have provided ideal conditions for these insects to thrive. Their rising numbers not only affected the dinosaurs’ health, but also their food supply. Insects are important pollinators, and as their populations increased, they helped to spread flowering plants, which gradually replaced the ferns, cycads, and gingkoes that dinosaurs traditionally ate.
The Poinars argue that insects and dinosaurs were locked in a “life-or-death struggle” for survival, and that the insects ultimately won.
Evidence for the Insect Extinction Theory
The Poinars’ theory is supported by a number of lines of evidence:
- Pathogens in insects: The discovery of pathogens for leishmaniasis, malaria, and other diseases in amber-preserved insects suggests that insects were a major source of disease for dinosaurs.
- Parasites in dinosaur feces: The presence of intestinal parasites in fossilized dinosaur feces provides further evidence that insects were affecting the health of dinosaurs.
- Changes in dinosaur diet: The spread of flowering plants, which are pollinated by insects, led to a decline in the availability of the plants that dinosaurs traditionally ate. This change in diet may have weakened dinosaurs and made them more susceptible to disease.
Implications of the Insect Extinction Theory
If the Poinars’ theory is correct, it would have significant implications for our understanding of the dinosaur extinction. It would mean that insects played a more important role in the extinction than previously thought. It would also suggest that the extinction was a more gradual process than is commonly believed.
Conclusion
The Poinars’ theory is a provocative and well-supported challenge to the traditional view of the dinosaur extinction. It is a reminder that even the smallest creatures can have a major impact on the course of history.