Pseudopulex and Yutyrannus
Pseudopulex is a Jurassic-Cretaceous flea many times bigger than any modern flea, 50x the size of, say, dog fleas. We think it was adapted to penetrate thick dinosaur skin with a serrated stylet! Yutyrannus is the world's biggest known feathered dinosaur. Hailing from the high-altitude Yixian Formation in China, its fluff at such a large size may be due to the temperate, cool climate it may have experienced.












