This marine lizard might be the coolest animal on the list, a kind of hybrid that looks like a crocodile mated with a dolphin. It's also one that experts didn't know existed until recently. By piecing together fossil remains first discovered in 1959, Scottish researchers determined that the Dearcmhara – Scottish-Gaelic for "marine lizard" – likely made its home in the then-warm waters off Scotland's west coast some 170 million years ago. The scientists announced their discovery of this new genus of ichthyosaur (sea-going reptile) in January 2015 [source: Moss].
Stretching roughly 14 feet (4.3 meters), the Dearcmhara Shawcrossi was believed to be near the top of the food chain in its day, likely dining on smaller fish and reptiles. Still, the animal is a smaller and more primitive version of the beasts that would come later in the Jurassic period (150 to 200 million years ago). By dating the Dearcmhara back to the same time frame, some researchers now believe that the shift to larger aquatic life may have been more subtle than the sudden shift in temperature of volcanic eruption some folks have theorized might have preceded the change [sources: Moss, Bittel].