Picture an otter donning a beaver's tail as a fashion statement, and voilà, you have the Castorocauda, a peculiar critter that meandered through what is now China roughly 20 million years back.

This quirky semi-aquatic mammal was kitted out with paddle-like limbs and specialised teeth for snapping up fish. Not just content with being an adept swimmer, the Castorocauda moonlighted as a digger, too.   While it may not have won any aquatic ballet awards, its eclectic set of adaptations allowed it to thrive in its ancient ecosystem.

Despite being only about the size of a contemporary grey squirrel, the Castorocauda bags the title as the largest known Jurassic mammal. And though it might remind you of a platypus or beaver, it’s not closely related to either.