Researchers have now determined that hippos were likely some of the first large animals to migrate from Asia to Africa, swimming from one continent to the other roughly 35 million years ago. However, they certainly weren't the semi-aquatic giants they are today. Fossil evidence indicates that ancient hippos were no larger than modern sheep.
Experts recently stumbled upon a fossil of what may be the oldest multicellular organism ever seen. A recent study of the fossil has revealed that it is about 60 million years older than when it was believed the first multicellular organisms started to crawl out of the Earth's primordial sludge, implying that the textbooks are due for a pretty serious rewrite.