When the Amazon Flowed Backwards

What did life look like when the Amazon watershed flowed backwards? How did its direction shape the evolution of life around it? And what force could have possibly been strong enough to up-end one of the world’s mightiest rivers between then and now?

While the evolution of the butthole was a major breakthrough in animal development, its story might actually end with redefining what it means to have a butthole at all.

In 2003, a fossil belonging to a mammaliaform was discovered in an ancient lakebed in what's now China. It was an almost complete skeleton the size of a platypus, a find that complicated the history of mammaliaforms. It painted a picture of their explosive diversification, their mysterious disappearance, and how our own ancestors might have survived thanks to a leg up from some leafy allies…