So, it turns out the Chixculub impact did more than wipe out most of the dinosaurs (yesterday I was wishing it had done a more thorough job when a crow woke me up by cawing right outside my window at 8am when I wanted to sleep in).
It also completely changed tropical forests.
Before the impact, the dinosaurs roamed through conifer-rich, sparse forests with a much thinner canopy. This, no doubt, gave more space for larger animals.
Modern rainforests are broad leaved, full of flowering plants and tangles of vines.
They've proposed three theories for why, all of which might be correct:
- Dinosaur feeding and movement kept the forests more open by eating and trampling a lot of saplings.
- Ash from the impact greatly improved the soil. Conifers like sparse soil.
- Conifers didn't survive the global winter as well as flowering planets.
Oh, and another change was to the insect population. Before the impact, insects had evolved into close partnerships with specific host plants. Afterwards, the survivors had to branch out, and we see the same feeding marks on very different plants.
It was a major change to the landscape and it gave us the Amazon we know today. And makes us wonder what might come next...
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