Jigsaw puzzles have been a Christmas tradition in my house for as long as I can remember. Every year, my mother would set up a table next to the tree, and we’d sort the tiny shapes and fit together pieces between cooking and decorating and chatting. This annual pastime gives me huge appreciation for paleontologists, since even the hardest jigsaw challenge usually comes with a picture of what the thing should look like when you’re done. By contrast, fossil experts are often presented with a scattered array of parts that they have to fit together into a complete extinct animal—and sometimes nature really throws them a curveball.

Case in point: Helicoprion, a prehistoric shark relative identified based on its absolutely bonkers