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What Killed the Dinosaurs?

Introduction | Asteroid Impact | Volcanism | Mammal Competition | Continental Drift | Conclusion

Hypothesis: Mammal Competition

Extinction implies that the species that perish are poorly adapted to a changing set of conditions.

Faced with an evolving group of competing organisms -- the mammals -- perhaps dinosaurs were driven to extinction by competition.

Packs of small mammals would have competed with dinosaurs for food. And carnivorous mammals would have preyed on dinosaur eggs.

Not only did mammals likely compete with dinosaurs for resources, many species survived the end-Cretaceous extinction and subsequently came to dominate Earth.

Evidence for the Mammal Competition Hypothesis

Fossil Record
A gradual decline in the number of dinosaur species would likely mirror an equally gradual cause of their ultimate extinction. Conversely, a sudden "now you see them, now you don't" end to the dinosaurs implies a catastrophic cause. Depending on location and interpretation, the fossil record seems to say different things.

While mammals certainly prospered on the heels of the dinosaur extinction, it is unclear whether mammals and dinosaurs experienced little competition or if they regularly challenged each other for limited resources.

-> Did drifting continents change ecosystems so dramatically that dinosaurs were unable to adapt?

Introduction | Asteroid Impact | Volcanism | Mammal Competition | Continental Drift | Conclusion

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