Studying evolutionary biology is like studying a giant jigsaw puzzle with only half of the pieces in place so far. 150 years ago, Darwin conceived of the puzzle and since then, scientists have gradually been classifying the species in our world in phylogenetic categories. You know how sometimes when you're working on a puzzle, you find one piece that helps you fit in like 30 others? Well that just happened for Natalia Rybczynski and her colleages from the Canadian Museum of Nature. The species they found was named Puijila darwini, or "Darwin's young marine mammal," an apt name considering it fills in an important evolutionary link between modern day seals and walruses and the ancient land mammals they supposedly evolved from.